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  1. Thanks for a succinct and clear article. I was recently asked “How much time do we have?” (To do what was not specified!) This adds another dimension to the answer.

    Comment by Kevin McKinney — 15 Aug 2013 @ 7:37 AM

  2. Let me begin by saying that RealClimate.org is the best site on the web for scientifically accurate information about climate change. With respect to this posting, I do not question the findings of the studies the author cites, and I am convinced that sea level rise is a major problem that will require very expensive adaptation (not possible for all places).

    Having said all that, the author goes too far in suggesting that: (a) because GHG emissions remain in the atmosphere for a very long time, they commit us to a certain extent of sea-level rise over the course of up to 2,000 years; and (b) “Society needs to decide whether we want to give up, for example, the Tower of London, or put the brakes on climate change….”

    There is no warrant for the author’s implicit presumption that no technological innovations over the next 1,000 years could alter the relationship between carbon in the atmosphere and sea-level rise. Already, we have technology to reduce the terrestrial effects of GHG emissions by inserting sulfur aerosols (or other reflecting particles) into the upper atmosphere. (Whether doing so is a wise policy remains, at this point, a contested issue.)

    The author’s other implicit assumption that there is no feasible way to protect a coastal (or tidal) city from the effects of sea level rise is simply false. Amsterdam has been sitting below sea level for centuries, and yet we haven’t had to “give up” on the Rijksmuseum. Whether Amsterdam can technologically work its way around another few meters of sea-level rise, remains to be seen. This is not to say that coastal areas won’t suffer grievously from climate change; sea walls may protect a city, but only at the cost of inundating other (presumably less valued) coastal areas.

    The most important point, however, is that climate scientists do not make it any easier to convince skeptics (let alone deniers), when they draw the more dire, catastrophic conclusions from every study. It is far better to be parsimonious and limit conclusions to what can reasonably be inferred from the science, and leave the hyperbole to the “talking heads.”

    Comment by Dan Cole — 15 Aug 2013 @ 7:58 AM

  3. @Dan H,

    the Antarctic projection were obtained from the simulation of the past 5 million years by David Pollard and Robert De Conto published in Nature in 2009. The increase in snowfall on Antarctica is very likely to happen in a warming world. However what was not accounted for (and explicitly stated but not often recognized) in the last IPCC report is that the IPCC did not account for dynamic ice discharge from Antarctica. Now, in contrast to Greenland this is the strongest ice-loss process from Antarctica (currently about 99% of the ice loss) and thereby needs to be accounted for. In these simulation it is accounted for.

    I hope that helps.
    Anders

    Comment by Anders Levermann — 15 Aug 2013 @ 8:39 AM

  4. “There is no warrant for the author’s implicit presumption that no technological innovations over the next 1,000 years could alter the relationship between carbon in the atmosphere and sea-level rise.”

    I disagree. While it is true that one can imagine scenarios which do alter this relationship, the feasibility of *any* of them remains highly dubious. (Especially over, say, the next century, which likely will have the most influence on ultimate sea level rise.)

    Therefore, the presumption made is the most plausible one–hardly an unreasonable inference, nor ‘hyperbole.’

    Comment by Kevin McKinney — 15 Aug 2013 @ 9:55 AM

  5. Hi Anders

    Thanks so much for this explanation. I’m still puzzled by one thing. The LGM was about 3.5 degrees C colder but sea levels were 120 meters lower. This isn’t explained by the 2.3 meters per degree C. Is the explanation simply that the sea level relationship to temperature is non-linear and the slope of 2.3 meters per degree just happens to correspond to the current climate?

    Tony

    Comment by Tony Noerpel — 15 Aug 2013 @ 10:05 AM

  6. A documentary from 2010 still good, with many expert opinions explored this topic.

    Changing Sea level budget and Semi-Empirical models

    Comment by prokaryotes — 15 Aug 2013 @ 10:28 AM

  7. Ben Strauss’s analysis in PNAS takes the form of a commentary–are PNAS commentaries considered fully peer-reviewed, by the way?–based upon another recent analysis, cited as:

    Levermann A, et al. (2013) The multimillennial sea-level commitment of global warming. Proc Natl Acad Sci USA, 10.1073/ pnas.1219414110.

    The commentary PDF:

    http://assets.climatecentral.org/pdfs/Strauss-PNAS-2013.pdf

    [Response: These commentaries aren’t peer reviewed as far as I know. –eric]

    Comment by Kevin McKinney — 15 Aug 2013 @ 10:31 AM

  8. @Dan H,

    limit conclusions to what can reasonably be inferred from the science

    I disagree, and The futility of “just the facts” climate science is a recent article which explores why.

    Comment by prokaryotes — 15 Aug 2013 @ 10:34 AM

  9. Isn’t the term “commitment” a bit too strong?

    The half life of the CO2 we emit is about 200 year, right. So the “commitment” would only be for the coming centuries and not indefinite, which the term suggests, or for 2000 years.

    I would not be surprised if at a certain time renewable energy is so much cheaper as fossil fuels, that the greenhouse gas emissions will go down to almost zero again. Thus maybe it would be a good (additional) alternative scenario to assume that the temperature will peak and not stay constantly high for 2000 years.

    [Response: The half life of CO2 isn’t really 200 years. It’s not a simple exponential function. About 10% of what we produce will be in the atmosphere for tens of thousands of years. See David Archers various publications on this, and his early RealClimate post, here. –eric]

    Comment by Victor Venema — 15 Aug 2013 @ 11:10 AM

  10. Anders. Thanks for the new computations. Could you comment on the possible validity of Dr. Jim Hansen’s view that we may see exponential behavior – doubling every decade or so.

    Comment by Ronal Larson — 15 Aug 2013 @ 11:43 AM

  11. Thank you for a superb summary. Your last statement that we must decide – is key.

    We don’t yet have universally widespread education/information, but certainly rising seas will deliver the message better than any other communication medium. Species-level wisdom must precede decision making. And humans have never globally unified on any course of action. Our first task is to decide to decide. This may entail an evolutionary leap in species commitment to survival.

    Comment by richard pauli — 15 Aug 2013 @ 12:08 PM

  12. I think a key question is how much sea level can rise. My own back-of-the napkin estimate is 60 m, based on estimated ice volumes in Antarctica and Greenland alone. This does not account for thermal expansion, nor changes in the Earth’s mass distribution that are already recognized to be taking place. So, some places won’t get this much sea level rise, and others, possibly much more.
    If we were seeing some real, significant progress in curbing carbon emissions, perhpas there would be no cause for alarm. The fact is, however, the rate of emissions is still increasing. In the US, the actions of a completely irresponsible oil and gas industry that peddles its misinformation to the poorly-educated voter masses, makes doing anything significant unlikely in any near-term scenario.
    Amsterdam and the Dutch have a commendable record of holding back the sea, but a few cm per century is an order of magnitude less than what they need to deal with in the future.
    I’ve seen little in the way of realistic political action anywhere in the US, and little prospect of this changing until disaster becomes too obvious for the denialists to maintain any credibility.
    So, we shouldn’t be alarmist? I have grand children; they will have to live with the consequences of my generation’s failure to act. It will be very expensive and very dangerous. It will result in economic and social instability. I am and remain alarmed, and I do not agree with those who call for sugar-coating the message about our future.

    Gene Hawkridge
    Kenmore, WA, USA

    Comment by Gene Hawkridge — 15 Aug 2013 @ 12:59 PM

  13. @3 Very sorry about sulfur aerosols. They don’t stay up that long. They have to be continually replenished. Every sort of magic trick is going to be sold for climate change. ‘Technology’ is way too good a word for it.

    Beyond that, “the…implicit presumption[s]” for which “there is no warrant” are all yours, sorry to say.

    There is some remediative tech that can help, but it’s not about messing with the atmosphere or the oceans. Remediative tech should be land-based. It should be easy to test, audit, reverse, and discontinue.

    The technologies for preventing sea-level rise (beyond what’s already in process) are known, or clued-in. They are methods of generating electricity that don’t burn fuel and don’t use, or cycle, huge amounts of water.

    Non-dependence on toxic waste is also important.

    Ponder what tech can do with that, starting now, over the next 1000 years, please.

    Fixing it backwards is not an answer, it’s a panic.

    The best way to fix it is to prevent it. The best way to fix it is to prevent it. The best way to fix it is to prevent it.

    Comment by patrick — 15 Aug 2013 @ 1:00 PM

  14. Not enough attention has been given to the long term. A thousand years is not so long; many European cities have buildings which are older.

    I remember being struck by this comment in the IPCC TAR of 2001

    Ice sheets will continue to react to climatic change during the next several thousand years, even if the climate is stabilised. Together, the present Antarctic and Greenland ice sheets contain enough water to raise sea level by almost 70 m if they were to melt, so that only a small fractional change in their volume would have a significant effect.

    Models project that a local annual average warming of larger than 3°C, sustained for millennia, would lead to virtually a complete melting of the Greenland ice sheet with a resulting sea level rise of about 7 m. Projected temperatures over Greenland are generally greater than globally averaged temperatures by a factor of 1.2 to 3.1 for the range of models used in Chapter 11. For a warming over Greenland of 5.5°C, consistent with mid-range stabilisation scenarios (see Figure 26), the Greenland ice sheet is likely to contribute about 3 m in 1,000 years. For a warming of 8°C, the contribution is about 6 m, the ice sheet being largely eliminated. For smaller warmings, the decay of the ice sheet would be substantially slower (see Figure 27).

    Ref.

    Can you imagine how the nuclear industry would be treated if they argued that it was unnecessary to secure nuclear waste for as long as a thousand years?

    Comment by deconvoluter — 15 Aug 2013 @ 1:20 PM

  15. This work impelled me to do my own comparison of global sea level (CSIRO & U Colo) vs global surface temperature (NCDC), 1880-2012. Empirically, the relationship is about 2.1 m per deg C. Quite close to this blog entry’s 2.3 m per deg C. I’ll be glad to email a copy of the work if you like. rgquayle@gmail.com

    Comment by Rob Quayle — 15 Aug 2013 @ 2:08 PM

  16. The comments about technological innovation saving us miss the point; we are not the world. Starting something we don’t know how to control and aren’t smart enough to quit making worse, trusting some Deus Ex Machina answer will appear, is tragedy.

    Comment by Hank Roberts — 15 Aug 2013 @ 2:11 PM

  17. We are currently at 0.8C or 0.9C above pre-industrial.

    We are thus committed to a minimum of about 1.82M more SLR.

    In reality, we are committed to temps thirty years from now and that level of SLR PLUS any increased temps due to emissions from this point forward.

    That’s an easy 3M SLR, I’d guess.

    I’m certain the recent findings by Box and others as to the ice sheets being more dynamic than thought will cause upward revisions in terms of how quickly SLR can occur.

    Oops.

    Query: I’ve seen this questioned asked exactly zero times, but it is the key question, imo. Were we to get CO2 back to 270ppm within 50 – 100 years, to what extent would that reduce future SLR? Said another way, what is the thermal response of ice sheets to reducing CO2 significantly?

    We may be seeing a hysteresis in the Arctic with the very ice reduction in question shifting seasons so much that ice formation is pushed well into winter and ice melt is pushed consistently into March. The changes to the Jet Stream seem to be bringing a consistent positive Arctic Oscillation and more cloudiness and cool temps this summer and last summer which might be slowing ice loss. (Last year’s melt would be partially due to thermal inertia in the Arctic with that abating somewhat this summer in this scenario and, were that trend to continue, it would possibly continue into future summers and possibly lead to a period of relative stability at this new 2012-2013 level until thermal inertia in the oceans overpowered this or the system reverted to pre-Jet Stream jerrymandering.)

    Anywho… if we can reduce CO2 to pre-industrial, what is the effect on the ice sheets?

    Comment by Killian — 15 Aug 2013 @ 2:22 PM

  18. I’m having trouble understanding why a model would predict a decrease in sea level rise due to antarctic ice melt as temperature increases, even “temporarily”, as illustrated in Figure (d) at ~3.9 C. The PNAS paper indicates these are physical models, not observations. I would expect all contributions to be smooth functions, like (a) (b) and (c).

    Also, why does the PNAS paper this post summarizes have a completely different effect for the Greenland ice sheet, indicating a dramatic rise of 6 meters at just 1.5 C? This also dramatically changes the overall value predicted in (e) to ~15 m at 4 C.

    Comment by AJ — 15 Aug 2013 @ 2:56 PM

  19. Re. my second question in the previous post, I see now that the figure here is the commitment for the next 2,000 years, corresponding to Figure 2 in the PNAS paper, as opposed to the reconstruction in Figure 1.

    Comment by AJ — 15 Aug 2013 @ 3:02 PM

  20. This from the 8/12 NYT article on locked-in SLR:
    “Benjamin Strauss and his colleagues at Climate Central, an independent group of scientists and journalists in Princeton that reports climate research, translated the Levermann results into graphical form, and showed the difference it could make if we launched an aggressive program to control emissions. By 2100, their calculations suggest, continuing on our current path would mean locking in a long-term sea level rise of 23 feet, but aggressive emission cuts could limit that to seven feet.”

    Comment by S.B. Ripman — 15 Aug 2013 @ 3:49 PM

  21. With no intention to distract, I note, on the subject of SRM (raised above):

    “Remember, in this new era, nature is us.”–Nobel Laureate Paul Crutzen “Living in the Anthopocene”

    http://e360.yale.edu/feature/living_in_the_anthropocene_toward_a_new_global_ethos_/2363/

    “A contemporary giant of science, the Nobel laureate Paul Crutzen, has rekindled the SRM debate in 2006 through an essay on stratospheric sulfur injection (17). However, he has consistently argued then and ever since that such a climate-engineering scheme would be implemented out of despair only, that is, if the establishment of any “conventional” climate-protection measure (like a worldwide cap-and-trade system for greenhouse gas emissions) failed. …

    “On closer inspection SRM [‘solar radiation management’] exhibits traits of MAD [‘mutually assured destruction’]. …” –John Schellnhuber

    “Geoengineering: The good, the MAD, and the sensible.” Published online 12 Dec 2011, doi: 10.1073/pnas.1115966108 PNAS December 20, 2011, vol. 108 no. 51

    http://www.pnas.org/content/108/51/20277.full

    “Last, efficiency and renewables will achieve something that [ex-post-fixit] approaches do not even care to consider: laying the foundations for a sustainable global energy supply system that (i) can virtually exist forever, and (ii) offers more equitable opportunities for the developing world…

    “In essence, humankind should avoid betting on the fabrication of a silver bullet for shooting climate change. Our world does not need SRM…in the first place, but rather a novel way of going MAD: ‘mutual assured decarbonization.’ ”

    [In the last quote I have substituted “ex-post-fixit” for the “g”-word. ‘Gee-oh!’ works, too, I think. I’d like to keep the “g”-word, itself, for things worthy of the name–involving forethought and foresight.]

    John Schellnhuber, PNAS profile: http://www.pnas.org/content/105/6/1783.full

    To exit an addiction, or a reversible illness, it’s helpful to ask: what do you want to do for the rest of your life?

    To exit an addiction to types of progress that are like home run records made on steroids, it’s helpful to ask: what do you want to do for the next 2000 years, to start with?

    Science on the long-term effects of present action is sobering and very healthy, if you let it in.

    Thank you, Anders Levermann. On the excellent NYT article, my luck’s holding, because I said: Justin Gillis hasn’t confused anyone yet.

    Comment by patrick — 15 Aug 2013 @ 5:04 PM

  22. Two comments on comments.

    (1) Dan Cole urges faith in technological innovation. I acknowledge we could get clever, but the prospects are truly daunting, not only because of the reliance upon as-yet-to-be-developed methods, but because the Earth is a big place, and ANY method will need to scale, cheaply in cost and cheaply in energy usage. So, there are THREE challenges, not just the science: technology, cheapness of energy use, and cost for global build-out, while the economies of the world are driving towards zero emissions. Realize, to make 450 ppm it’s estimated the globe needs to start reducing its emissions by 2020, not just its rate of emissions. And there will be economic costs to do this, in addition to deploying the Magical Technology to fix the coupling between atmospheric CO2 and sea-level rise. It’s not only about energy, it’s where the energy goes. Sea level rise has multiple components, with ice melt being long term big, as the article says, but thermal expansion having a significant piece, too.

    (2) “Were we to get CO2 back to 270ppm within 50 – 100 year” … Not sure but it sounds like Killian may be confusing emissions with accumulation. Might reduce emissions, but drawing down CO2 means carbon dioxide REMOVAL (not capture and sequestration), irrespective of what is done with aerosols. For global deployment and assuming it can be done at all, that’s priced at trillions of U.S. dollars per annum. The contingency is that this needs to be done at an ENERGY COST for manufacture and operation which does not significantly affect emissions, which need to be rapidly approaching zero for this to make sense. In net, we need to run negative emissions for a time.

    Reference: “Atmospheric Lifetime of Fossil Fuel Carbon Dioxide”, Archer, Eby, et al, Annu. Rev. Earth Planet. Sci. 2009. 37:117–34. Pertinent finding is that 20%-35% of atmospheric CO2 remains for 3000-7000 years. The remainder equilibrates with oceans on a scale of 2-20 centuries.

    Reference: http://e360.yale.edu/feature/pulling_co2_from_the_air_promising_idea_big_price_tag/2197/

    Comment by Jan Galkowski — 15 Aug 2013 @ 5:53 PM

  23. Killian @18 — Reducing CO2 to pre-industrial concentrations would eventually lead to the formation of as much ice as was present then.

    Comment by David B. Benson — 15 Aug 2013 @ 7:03 PM

  24. Personally, I’m changing my prediction to imagining the icecaps behaving like ‘shatterproof’ glass — fracturing into zillion of little blocks.

    Say some summer day, some critical number of surface ponds suddenly disappears, having melted through, raising the bottom temperature to where it lets other cracks melt through, and drain, lather rinse repeat — and the ice caps !sproing! break up along whatever stresses existed, turning all of the ice all at once into piles of ice cubes, which then rush to the ocean.

    “Walk faster, the ocean’s rising all of a sudden….”

    I’ll save that for my big scary blog, if I ever start one. Or a novel ….

    Comment by Hank Roberts — 15 Aug 2013 @ 9:08 PM

  25. 1 Dan H said, “Many other predictions claim that much greater warming would need to occur before Antarctica ceases to accumulate ice”

    You’re confusing East Antarctica with Antarctica. Antarctica is already losing ice.

    http://www.realclimate.org/index.php/archives/2012/11/weighing-change-in-antarctica/

    Comment by Jim Larsen — 15 Aug 2013 @ 10:01 PM

  26. In net, we need to run negative emissions for a time.

    Obviously, so that isn’t the question I was asking. Assume everything else, regardless of how achieved, and get to the bottom line: If we reduce to 270 ppm in 50 – 100 years, and stay there, what is the effect?

    David B. Benson says:
    15 Aug 2013 at 7:03 PM

    Killian @18 — Reducing CO2 to pre-industrial concentrations would eventually lead to the formation of as much ice as was present then.

    Again, obviously. Didn’t realize the basics would confuse.

    The context of the article was TIMING. So… bearing the context in mind, reduce in that time frame, stay at that level, what is the result in terms of hysteresis on melt of the various forms of ice and rebuilding those various masses, thus eventually lowering of SLR after what peak?

    Comment by Killian — 15 Aug 2013 @ 11:28 PM

  27. and the ice caps !sproing! break up along whatever stresses existed, turning all of the ice all at once into piles of ice cubes, which then rush to the ocean.

    That’s more my suspicion at the moment. We have no history, no data, no anything at all to believe that conditions we’ve not seen before will simply mean more and faster of what we have seen before.

    Paleo results tell us mainly how things finished up after these processes had done their work, they don’t give us too many hints of what can happen in a few decades or a couple of centuries during the process itself. And the collapse of summer sea ice within just one decade tells us that we really would be a bit silly if we relied too strongly on our projections based on historical data.

    Whatever happens, I very much doubt it will simp0ly be more of the same, but a bit faster, even if it’s not this particular scenario.

    Comment by adelady — 16 Aug 2013 @ 12:06 AM

  28. AJ @19.
    The reason for the dips in graph d is probably due to projected increases in snowfall over Antarctica.

    Comment by MARodger — 16 Aug 2013 @ 3:54 AM

  29. @21, S.B.Ripman:
    “… By 2100, their calculations suggest, continuing on our current path would mean locking in a long-term sea level rise of 23 feet, but aggressive emission cuts could limit that to seven feet.”

    SEVEN FEET?! Even after ‘aggressive emission cuts’? Not much hope for central London, then, or indeed for many British seaside towns and villages. Even a 1 foot rise would entail problems in many of our coastal areas.

    On another point, but related to this topic, and for someone who is a scientist by not a climate scientist. My v. rough understanding of the present temperature trends is that warming appears to have “stalled” for the time being (with respect to air temps, anyway), but since the heat must still be going somewhere, it’s probably going into the oceans instead. Thus, the rate of sea level rise over the next decade or so will probably be somewhat faster than formerly predicted by the IPCC/whoever, owing to more thermal expansion. Is that about right?

    Thanks.

    Comment by Nick O. — 16 Aug 2013 @ 4:22 AM

  30. What are the chances of the oceans becoming anoxic to the point that H2S or Hydrogen Sulfide becomes a serious problem for humans in this century?

    Comment by Chuck Hughes — 16 Aug 2013 @ 4:39 AM

  31. Chuck:
    The chances are essentially zero that the oceans will become anoxic. There is plenty of deep circulation to feed oxygen down.

    Comment by mitch — 16 Aug 2013 @ 6:50 AM

  32. [correction] The executive summary of the 2007 IPCC report said that “Global sea level was likely between 4 and 6 m higher during the last interglacial period, about 125 ka, than in the 20th century. In agreement with palaeoclimatic evidence, climate models simulate arctic summer warming of up to 5°C during the last interglacial. The inferred warming was largest over Eurasia and northern Greenland, whereas the summit of Greenland was simulated to be 2°C to 5°C higher than present. This is consistent with ice sheet modelling suggestions that large-scale retreat of the south Greenland Ice Sheet and other arctic ice fields likely contributed a maximum of 2 to 4 m of sea level rise during the last interglacial, with most of any remainder likely coming from the Antarctic Ice Sheet.”
    What are the PAGES scientists saying now.

    Comment by Pat Saunders — 16 Aug 2013 @ 8:53 AM

  33. @Dan Cole (comment #3)

    Please consider that we are talking about adaptation of infrastructure and cities not about computer chips and that 2000 years is an upper limit for the time it takes for this too occur. Sure, we cannot even imagine the technology that we will have at hand in the far future, but again Hamburg is a coastal city and it is more than 700 years old. Even if you unplug it and move it to another place it is not the same as it was before, neither will it be the same if we build a 3 meter wall around it. Cultural heritage, infrastructure and the like are inert and big.

    Comment by Anders Levermann — 16 Aug 2013 @ 9:00 AM

  34. adelady @28 We do have some paleo evidence that nearing the height of the last interglacial about 121k b.p., there was a rapid sea level rise of 2-3m “on an ecological timescale” i.e. faster than coral in a sheltered lagoon could grow upward to keep up with the rise. This occurred when sea levels were already about 3m above present values. See http://www.nature.com/nature/journal/v458/n7240/abs/nature07933.html for more information.

    Comment by John Pollack — 16 Aug 2013 @ 9:23 AM

  35. Asteroid strikes get all the coverage, but “Medea Hypothesis” author Peter Ward argues that most of Earth’s mass extinctions were caused by lowly bacteria. The culprit, a poison called hydrogen sulfide.

    http://www.ted.com/talks/peter_ward_on_mass_extinctions.html

    Comment by Chuck Hughes — 16 Aug 2013 @ 9:56 AM

  36. > Assume everything else, regardless of how achieved

    No change in aerosols?
    No change in black carbon?
    No change in CO2 dissolved in oceans?

    Or do you mean, put everything back 200 years except the current sea level and ask which way it’d trend and how fast and where would it end up?

    Connections are too complicated to answer your simple question as posed.

    Comment by Hank Roberts — 16 Aug 2013 @ 10:11 AM

  37. Mitch:

    The chances are essentially zero that the oceans will become anoxic. There is plenty of deep circulation to feed oxygen down.

    I wouldn’t be so quick to dismiss ocean anoxia as a possible consequence of AGW, albeit one that would take thousands of years to develop. I’ve just finished reading Peter Ward’s Under a Green Sky. He makes a convincing argument that the Permian-Trassic mass extinction (and probably other extinction events) was caused by global warming from GHGs released by volcanic eruptions, which shut down deep circulation in the oceans, resulting in multiple episodes of ocean anoxia, and the release of toxic quantities of H2S into the atmosphere.

    Comment by Mal Adapted — 16 Aug 2013 @ 10:45 AM

  38. Me: “Permian-Trassic” – that’s “Permian-Triassic”, of course

    Comment by Mal Adapted — 16 Aug 2013 @ 10:47 AM

  39. The chances are essentially zero that the oceans will become anoxic. There is plenty of deep circulation to feed oxygen down.

    Excuse me, but the loss of our ice sheets, the warming and overturning of our oceans and ocean anoxia is the inevitable result of this phenomenon if left unabated.

    It’s just a matter of time.

    Comment by Thomas Lee Elifritz — 16 Aug 2013 @ 10:58 AM

  40. @Victor Venema (10) – Excess atmospheric CO2 doesn’t have a single half life, but subsides at declining trajectories as CO2 is absorbed and buffered in the upper ocean (about half in 1-2 centuries), equilibrated with the deeper ocean and buffered by carbonate dissolution, followed by carbonate restoration through weathering of terrestrial rocks – the last processes requiring thousands to hundreds of thousands of years. If CO2 emissions ceased, all other things equal, temperature would not remain absolutely steady, but would vary little on centennial scales since the declining warming effect of the excess CO2 would be largely balanced by the slow surface warming from the thermal inertia of the oceans for an extended interval. For a useful analysis, see the PNAS paper by Susan Solomon et al at Irreversible Climate Change.

    Comment by Fred Moolten — 16 Aug 2013 @ 11:01 AM

  41. > adelady says:
    > 16 Aug 2013 at 12:06 AM
    >>
    >> and the ice caps !sproing! break up along whatever stresses
    >> existed, turning all of the ice all at once into piles of
    >> ice cubes, which then rush to the ocean.
    >
    > That’s more my suspicion at the moment.

    That scenario was poking fun at fantasy-climate-blogs.
    Please don’t take this kind of goofiness seriously.
    Fantasy disasters play purely to people’s fears.
    Look for citations to science journals. Read. Think.
    If you think you understand it, cite to and blog about what you understand.

    Comment by Hank Roberts — 16 Aug 2013 @ 11:25 AM

  42. The 2012 paper from Foster and Rohling http://www.pnas.org/content/110/4/1209.full suggests that the paleo record implies a sea level rise of about 14m for doubled CO2 whereas your work implies about 7m.

    Could you comment on how you think your work squares with that of Foster and Rohling?

    Comment by mdenison — 16 Aug 2013 @ 11:58 AM

  43. So what about photosynthesis? If the removal goal is 100 ppm that equals 210 GTC. Currently around 2200 GTC are held in soils and plants. Many ecosystems are carbon-depleted due to human activities such as deforestation, conventional agriculture and development. More carbon can circulate though forests with reforestation, afforestation and longer-rotation management of timber lands. More carbon can circulate through farm soils through no-till, residue management, returning organic carbon to soils, cover crops. Wetlands restoration can rebuild carbon-rich ecosystems. An added bonus is that these land management changes improve resilience of forests, agriculture and ecosystems under increased climate extremes. The challenge is to build economic and policy models that provide incentives for change. Perhaps a devotion of a certain percentage of eventual carbon revenues can contribute, supporting carbon-negative practice changes (as opposed to carbon-neutral offsetting). We can hope that technological CO2 removal modalities in development by scientists such as David Keith prove economical and feasible. But photosynthesis is available now, and can be unleashed for CO2 removal by known practice changes. Any problems in this picture?

    Comment by Patrick Mazza — 16 Aug 2013 @ 12:39 PM

  44. Correction to comment 16: Empirical sensitivity seems to be about 212 mm per deg. C.

    Comment by Rob Quayle — 16 Aug 2013 @ 12:59 PM

  45. Killian @18 — Reducing CO2 to pre-industrial concentrations would eventually lead to the formation of as much ice as was present then.

    I’m not so sure about that. That ice was formed during the last glacier period. It has been melting for the last 11,000 years, so why do you think it would reform?

    Comment by bibasir — 16 Aug 2013 @ 1:00 PM

  46. mdenison #43,

    Foster & Rohling (2013) say:
    “Given the present-day (AD 2011) atmospheric CO2 concentration of 392 ppm, we estimate that the long-term sea level will reach +24 +7/−15 m (at 68% confidence) relative to the present.”

    Where in the paper do you read that they suggest the paleo record implies about 14m rise for doubled CO2?

    Comment by Lennart van der Linde — 16 Aug 2013 @ 3:34 PM

  47. bibasir
    where do you get ” It has been melting for the last 11,000 years”?
    Have a look at http://www.globalwarmingart.com/wiki/File:Ice_Age_Temperature_Rev_png
    the typical ice age ends suddenly (as one did about 11,000 years ago); then, typically, a very slow cooling progresses. We interrupted that, this time.

    Comment by Hank Roberts — 16 Aug 2013 @ 4:57 PM

  48. For those who (incorrectly) observe that I have too much faith in technology, when I was merely questioning Anders’ complete neglect of the possibility, I offer the following quote from Tom Schelling: “Seventy years ago we did not have electronics, radioisotopes, nuclear energy, antibiotics, genetics, satellites, or even plastics—it was all silk, rayon, isinglass, and celluloid. How do we possibly foresee seventy years from now?” Thomas C. Schelling, “What Makes Greenhouse Sense?” Indiana Law Review 38:581-593 (2005), at 586.

    In any case, we should not worry so much about rich cities as millions of poor Bangladeshis engaged in subsistence agriculture on floodplains that will be inundated long before any rich city disappears beneath the waves.

    Comment by Dan Cole — 16 Aug 2013 @ 7:35 PM

  49. > Tom Schelling
    Same point from John Nielsen-Gammon, but
    Consider that we’ve overshot carrying capacity
    So we may not have more of this lovely tech progress
    going on forever.
    Stein’s Law may apply: If something cannot go on forever, it will stop.

    That’s the worry — that we’ll leave a generation or two in the future without the lovely surpluses and freedoms we got by consuming the Americas and most of what lives in the oceans, did that over a period of a couple of centuries, all that lovely free lunch, and now it’s almost all gone.

    What will we do next? When the cornucopian approach fails? You can find Catton’s _Overshoot_ many places; here’s a quote from one online excerpt — he’s describing the lesson that could have been learned from the Great Depression:

    “… With breakdown of the mechanisms of exchange, various segments of a modern nation had to revert as best they could to living on carrying capacities again limited by locally least abundant resources, rather than extended by access to less scarce resources from elsewhere. Although scope reduction hurt everyone, rural folk had local resources to fall back upon; urban people, in contrast, had so detached themselves as to have almost ceased to recognize the indispensability of those resources. For reasons we shall examine in a moment, economic hard times hit the farms sooner than they hit the cities, but in the final scope-reducing crunch the farmers turned out to have an advantage sufficient to interrupt a clear trend of urbanization.
    No Fairy Godmother

    The Depression also interrupted the advance of industrialization and its attendant occupational diversification of the population. With hindsight, that interruption becomes an opportunity to bring the previous diversification into ecological focus.

    An ecological perspective enables us to see pressure toward niche diversification as the natural result of the overfilling of existing niches. Among non-human organisms, this pressure leads eventually to the emergence of new species. Among humans it leads through sociocultural processes to the emergence of new occupations …

    … In nature, overfilling of old niches can result in massive death. Many organisms fall by the wayside in the march of speciation. Among human organisms the principles hold, but the process is moderated because humans are occupationally differentiated by social processes rather than by biological processes. Ostensibly, when old niches become obsolete, we can retrain ourselves for new roles. So, for Homo sapiens, overpopulation and death are avoidable results of niche saturation. The avoidance is not easy, however, and retraining for new niches can be traumatic.

    An ecological perspective thus heightens the significance of a classic sociological study that clearly showed how unlikely it is, even among members of the relatively flexible and plastic human species, that re-adaptation to new niches (as old ones close up) will occur easily or automatically.

    Comment by Hank Roberts — 16 Aug 2013 @ 8:07 PM

  50. We have learned a lot about the north polar ice cap. We are learning a lot more about Greenland, right now. But it seems to me that we are far behind where we’d like to be in understanding Antarctica — both West and East. I recall a July 2013 AGU youtube discussion about just how little predictability the state of knowledge today provides for the West. And I believe this also applies equally to the East.

    Just this last week or two I have read about paper on Antarctica that perhaps highlights important changes in prior understanding, as the following link from the University of Washington discusses:

    http://www.washington.edu/news/2013/08/14/earth-orbit-changes-were-key-to-antarctic-warming-that-ended-last-ice-age/

    Reading between the lines, I take this as a segue for some pretty serious questioning of prior estimates, even relatively recent ones. I do understand that this is a new report and it takes time for others to search out problems, do further research, etc. But it does give me pause, too.

    It’s potential re-alignments in our knowledge like this that give me pause when reading relatively conservative (assume 0th order [no change, just constant] when you have no information, assume 1st order [linear] when you have vague idea about local trend lines, assume more ONLY if you have good theory AND lots of experimental result) estimates, which I see (despite phrases as “quasi” linear) essentially as a relatively ignorant linear assumption absent better knowledge.

    In the meantime, I’m not assuming that current quasi-linear projections are anything more than reflective of how little we really know.

    Seeing quasi-linear models of ice does NOT exactly comfort me. It makes me think, instead, we have a long ways yet to go.

    Comment by Jon Kirwan — 16 Aug 2013 @ 9:09 PM

  51. Killian @27 — Ice sheets and glaciers grow snowflake by snowflake but melt everywhere lower than the freezing line: a long time to reform the ice mass. Think in units of centuries.

    Comment by David B. Benson — 16 Aug 2013 @ 9:17 PM

  52. 49 > In any case, we should not worry so much about rich cities as millions of poor Bangladeshis engaged in subsistence agriculture on floodplains that will be inundated long before any rich city disappears beneath the waves.

    Tell them that in Red Hook.

    Certain non-linear effects, so to speak, are already kicking in–with insurance rates, for instance.

    Comment by patrick — 16 Aug 2013 @ 10:02 PM

  53. The observation that there will be decisions required on the fate of cities isn’t hyperbole at all. Superstorm Sandy and Katrina already showed how the message would be delivered. When the repair bill comes in, a preventative solution will require some Dutch thinking. A few more city hits and seaports around the world will get the message that they’re exposed. And as Fukushima learned, the safety margins engineered into the sea barrier were underestimated (a surprise tectonic shift) with disastrous consequences. Add that to the bill.

    An article question here is about allowance for something other than linear or curve projections. The NY Times link suggests a possibility of WAIS disruption because it’s like filling in a pie-shell. Interestingly enough, so is the center of Greenland. And the sudden rise late in the Eamian (17 feet) is a subset of Greenland’s potential contribution of 23 feet. The new warning sound buzzward may be ice-quakes. Any allowance for that possibility?

    Comment by owl905 — 17 Aug 2013 @ 12:51 AM

  54. Since I first saw the new maps published by British Antarctic Survey’s Bedmap2 project, I’ve been wondering if anyone has the capacity to model the effect of a sizable chunk of ice breaking free in a region where the ice is grounded deep below sea level, with a connection straight to the sea, If you look at their Cryosphere paper from earlier this year, a large fraction of the Antarctic is below sea level, more than I realized before. Visualise this sequence of steps:

    a piece of ice abutting the ocean is sufficiently lubricated from below by warming ocean
    this piece of ice cracks off and floats away
    it’s big enough for isostatic rebound to crack another big piece off
    a chain reaction starts with increasingly large seismic events as more and more mass breaks away, releasing the surface from most of the weight previously there

    Possible? Does anyone have the capacity to model this?

    That could result in a rather dramatic sea level rise.

    Comment by Philip Machanick — 17 Aug 2013 @ 9:04 AM

  55. Diverse calving patterns linked to glacier geometry
    Nature Geoscience (2013)
    doi:10.1038/ngeo1887

    “Here we present a numerical model that simulates the disparate calving regimes observed, including the detachment of large tabular bergs from floating ice tongues, the disintegration of ice shelves and the capsizing of smaller bergs from grounded glaciers that terminate in deep water. Our model treats glacier ice as a granular material made of interacting boulders of ice that are bonded together. Simulations suggest that different calving regimes are controlled by glacier geometry, which controls the stress state within the glacier. We also find that calving is a two-stage process that requires both ice fracture and transport of detached icebergs away from the calving front. We suggest that, as a result, rapid iceberg discharge is possible in regions where highly crevassed glaciers are grounded deep beneath sea level, indicating portions of Greenland and Antarctica that may be vulnerable to rapid ice loss through catastrophic disintegration.”

    My “Ice Cube Emergency” fantasy scenario above already has support in the literature, sigh.

    Comment by Hank Roberts — 17 Aug 2013 @ 11:26 AM

  56. for Philip (maybe a duplicate post, tried once already), this sounds similar to the modeling you’re wondering about:
    http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1887.html
    Diverse calving patterns linked to glacier geometry
    Nature Geoscience (2013)
    doi:10.1038/ngeo1887
    “… Our model treats glacier ice as a granular material made of interacting boulders of ice that are bonded together. Simulations suggest that different calving regimes are controlled by glacier geometry, which controls the stress state within the glacier….”

    Comment by Hank Roberts — 17 Aug 2013 @ 12:24 PM

  57. Philip, #55

    I think isostatic rebound is a very slow process.

    There are a several things that should work much more quickly.

    1) Basal melt from the warming ocean
    2) Reduced resistance to the glacial flow from open ocean vs a higher grounding line
    3) Cracks from surface melt pond drainage breaks up the end of the ice; over the ocean it floats away.

    This feels like one of the dynamic, non-linear processes that are hard to model, and one that could have significant impacts.

    Comment by David Miller — 17 Aug 2013 @ 1:32 PM

  58. Philip,

    If the ice is already floating, when it breaks off there will be no isostatic rebound because the weight of the ice was supported by the ocean before it floated away.

    IMHO, what could happen is that some floating ice breaks off and the grounded ice behind it slides into the sea. This raises sea level, which breaks off other floating ice, which allows ice sheets behind them to slide into the sea.

    This may have happened at the end of the last glaciation because there is evidence that there were synchronised ice surges in both the west and east of the North Atlantic.

    Cheers, Alastair.

    Comment by Alastair McDonald — 17 Aug 2013 @ 2:46 PM

  59. @Fred Moolten (41). I know the CO2 concentration does not decay exponentially and that thus a half-life time is not fully appropriate. That is why I wrote *about* 200 years. Even if the relationship is more complex, if we stop emitting CO2, the CO2 concentration will be a lot lower in 2000 years. Thus stating that we now “commit” to a certain sea level rise sounds too strong to me.

    That being said, I am Dutch and would not like to see my home country disappear in the floods and do not want to downplay the importance of sea level rise. I even expect that the current political efforts to stay below 2°C temperature increase is too weak for The Netherlands. In the end we will have to get back to about the original temperature.

    Comment by Victor Venema — 17 Aug 2013 @ 3:42 PM

  60. Why have not the modelling and scientific community NOT availed themselves of the neural learning models to do some climate prediction?

    There is very good understanding of how well neural models work and why.

    It is also true that they are less transparent (the internal logic, weighting and definitions are harder to quantify).

    They would however, constitute an ENTIRELY different method of formulating a model and predicting a future state of the planet’s climate, and so would serve as a sort of “sanity check” on more physics intensive models.

    This question occurs to me because I have, based on the rubbish sloshing around in the personal “model” between my ears, been asserting 1.7 +/- 0.5.

    I have not ever had any way to explain WHY. The neural models are notorious for giving very little feedback that would be thought of as “science”, and the sort of intuition involved in the operation of a human brain is far far worse but… it WOULD be a potent sanity check for the community. Would it not?

    Comment by bjchip — 17 Aug 2013 @ 7:16 PM

  61. “A thousand years is not so long; many European cities have buildings which are older.”

    Perhaps part of the problem with communicating climate risks in the United States is an inborn LACK of that sort of historical perspective? I know I am repeatedly reminded that we rebuild our infrastructure continually.

    As for the technical solutions… the only one I have any hope for is Cheap Access to Space. Which, if we had it, would allow us to manage something relatively cheap and entirely reversible, as well as providing a source of energy that is ALSO cheap and CO2 free. Meantime I tell my Green friends that Nuclear ain’t as bad as having to build an Ark and we know how to burn the waste instead of storing it forever.

    Comment by bjchip — 17 Aug 2013 @ 7:35 PM

  62. Alistair #59, if the ice is grounded below sea level it’s not floating. If half of its height is above sea level the mass difference when it breaks clear, even if replaced by water, will be significant. Take a look at the Bedmap2 maps (fig 8 and 9). There are parts where the ice is 4km thick, grounded 2km below sea level (as far as I can tell from the colours).

    Hank #56, #57: Yes, this could be what I mean – assuming the paper goes on to cover some detail of the way ice not directly at the sea could come away (stupid paywall).

    If you examine the Fig 9 map on the left (slightly south of west) there is a patch that is dark blue indicating > 2km below sea level, with a path to the sea that is consistently grounded below sea level. Part of that region has ice coloured orange in Fig 8, indicating about 4km thick. Lose ice shelves in that region and start losing the ice progressively inwards from the coast, and the scenario I outlined could occur.

    Another interesting thing about the Bedmap2 paper is how little of the Antarctic ice is grounded above sea level. I already knew much of the west Antarctic ice is grounded below sea level. East Antarctic also has significant patches grounded > 1000m below sea level.

    Comment by Philip Machanick — 18 Aug 2013 @ 2:51 AM

  63. 59 Alastair M said, “IMHO, what could happen is that some floating ice breaks off and the grounded ice behind it slides into the sea. This raises sea level, which breaks off other floating ice,”

    Sea level rise is infinitely slower than ice flow. Besides, these shelves have to withstand tides. I think your scenario is impossible.

    Comment by Jim Larsen — 18 Aug 2013 @ 11:31 AM

  64. http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1889.html

    “Warm intervals within the Pliocene epoch (5.33–2.58 million years ago) were characterized by global temperatures comparable to those predicted for the end of this century1 and atmospheric CO2 concentrations similar to today…. Here we present new data from Pliocene marine sediments recovered offshore …. We interpret this erosion to be associated with retreat of the ice sheet margin several hundreds of kilometres inland and conclude that the East Antarctic ice sheet was sensitive to climatic warmth during the Pliocene.”

    That’s from

    Dynamic behaviour of the East Antarctic ice sheet during Pliocene warmth
    Nature Geoscience (2013) doi:10.1038/ngeo1889
    ___________
    ReCaptcha says: sortta much

    Comment by Hank Roberts — 18 Aug 2013 @ 11:49 AM

  65. Quite a few recent papers on ocean wave interactions with floating sea ice; extreme case here: http://www.ingentaconnect.com/content/igsoc/jog/2011/00000057/00000205/art00001
    “… illustrates the growing evidence of ocean-wave impact on Antarctic calving and emphasizes the teleconnection between the Antarctic ice sheet and events as far away as the Northern Hemisphere.”
    DOI: http://dx.doi.org/10.3189/002214311798043681
    Publication date: 2011-10-01

    General approach dealing with cavity size as well as ice thickness:
    http://www.ingentaconnect.com/content/igsoc/jog/2013/00000059/00000213/art00008
    ” These results suggest that both long ocean waves with periods of 100-400 s and shorter sea swell with periods of 10-20 s can have strong impacts on relatively short ice shelves and ice tongues by exciting oscillations with their eigenfrequencies, which can lead to iceberg calving and, in some circumstances, ice-shelf disintegration.”
    DOI: http://dx.doi.org/10.3189/2013JoG12J096
    Publication date: 2013-03-01

    Comment by Hank Roberts — 18 Aug 2013 @ 11:58 AM

  66. > bjchip …. NOT availed themselves of the neural learning models

    Would these be those?

    Comment by Hank Roberts — 18 Aug 2013 @ 1:59 PM

  67. oops, two tries and the software still swallowed the link behind “these” — I suggested you look at, for example, these:

    https://www.google.com/search?q=“neural+learning+model”+”climate+prediction”

    (copy and paste into a browser, the quotation marks likely break the link too)

    Comment by Hank Roberts — 18 Aug 2013 @ 2:00 PM

  68. Or, more better, for bjchip, try these. Look at the authors’ names.

    Comment by Hank Roberts — 18 Aug 2013 @ 8:28 PM

  69. Lennart van der Linde #47

    F&R paper makes the point that sea level has a range of possible values from +9 to +31m as you note – In the figures they indicate mid value of about 14m for a wide range of CO2 values from below 560ppmv and above. See their figures. I only picked 560ppm since it is a common ref point in a lot of discussion. The implications I read from F&R is of a greater sea level commitment than discussed by Anders Levermann and I think it would be interesting to hear an expert view point on these two different approaches.

    Comment by mdenison — 19 Aug 2013 @ 9:15 AM

  70. mdenison #70,

    Ok, in that broad sense I can follow you.

    Comment by Lennart van der Linde — 19 Aug 2013 @ 12:58 PM

  71. A “lurker” here!

    I am extremely frustrated by the constant “we’re doomed” approach of many of the posts and comments here. The very idea that we should be setting policy now to deal with a world that we have imagined in 1000 years is pure nonsense.

    If nothing else, the human race has demonstrated an unerring ability to adapt and change. Despite massive, global population expansion – we have a greater percentage of humans that are healthier, less hungry and living longer – and all this has happened in a 100 year span when the planet has warmed by a degree or so.

    This site accepts that further warming is inevitable – because the changes wanted are not happening or are not happening fast enough. So, how about applying some brain power to how we adapt to this inevitable change. How about looking at what benefits/advantages will come from warming and try and capitalise and maximise such benefits.

    … And let’s take this through to the end game. Does the whole human race wake up one morning and say it is now too hot – so I think I will die today. Of course not. Habitability will be affected over time and we will respond over time. Less land mass, less food – less humans being born – and so on. Maybe we end up with a few human populations dotted around the globe post apocalypse – and then we start all over again.

    Why is that not an acceptable plan for the next few 1000 years.

    Comment by Dave — 20 Aug 2013 @ 4:01 AM

  72. The very idea that we should be setting policy now to deal with a world that we have imagined in 1000 years is pure nonsense.

    Left unattended without carbon dioxide drawdown and atmospheric management the Earth will be uninhabitable for anything over several hundred million people living hunter gatherer lifestyles. Your point is entirely without merit. We only have one chance to repair this, and it requires all of the advanced technology and cutting edge reusable rocketry and condensed matter physics breakthroughs that we can manage. This is something that already requires two seperate federal crash programs akin to Apollo and Manhattan because of the sole reason it has been left unabated for the last 30 years, in which we have had all of the information we needed to determine this was a severe problem with a terminal outcome. Get real. If you want nonsense, look at yourself.

    Do you propose that we not track and identify all of the asteroids as well?

    Comment by Thomas Lee Elifritz — 20 Aug 2013 @ 8:21 AM

  73. Dave@71,

    The reasoning here seems to be naive confidence in the validity of extending any trend linearly into the future. By this reasoning an expanding population of yeast cells in a beer vat will expand forever.

    Dave,did it ever occur to you that there is another way of approaching these problems–that is, to anticipate threats before they bite us on the tuckus? Did it ever occur to you that the reason why humans have prospered so far has much more to do with the ability of some to accurately anticipate such threats than it does with the sort of naive optimism you seem to favor?

    Do you think the Green Revolution just “happened”?

    Do you think Y2K was all a fake?

    Do you think SARS wasn’t a real threat?

    Do you think smallpox just died out of its own accord?

    Are you really this dim?

    Comment by Ray Ladbury — 20 Aug 2013 @ 8:53 AM

  74. > Maybe we end up with a few human populations …
    > post apocalypse – and then we start all over again.
    > Why is that not an acceptable plan for the next few 1000 years.

    Because it’s insane. That lump on the end of your spine is supposedly capable of making better plans that that one.

    Oh, sorry, that was really good-smelling red herring.
    Ya caught me with that one.
    Got any more, chum?
    __________________
    ReCaptcha: “eAttsee assets”

    Comment by Hank Roberts — 20 Aug 2013 @ 9:16 AM

  75. Dave @71,
    You’re whistling past the graveyard, aren’t you?

    “Habitability will be affected over time and we will respond over time. Less land mass, less food – less humans being born – and so on. Maybe we end up with a few human populations dotted around the globe post apocalypse – and then we start all over again.”

    All that is true.

    “Why is that not an acceptable plan for the next few 1000 years.”

    Because it involves somewhere between 10s of millions and billions of excess deaths, untold suffering, the loss of a bunch of cities with enormous historical and aesthetic value, huge and unpredictable changes to the ecosystem, changes in growing patterns with huge impacts on agriculture, and so forth. And because the sooner we start acting decisively the better the outcome will be and the less immensely expensive and painful adaptations we will have to make, all in exchange for exercising a bit of foresight?

    (If you were being sarcastic I apologize for responding as if you were serious, it’s difficult to tell sometimes.

    Comment by Douglas McClean — 20 Aug 2013 @ 9:40 AM

  76. Dave @ 71.
    You tell us – “Maybe we end up with a few human populations dotted around the globe post apocalypse – and then we start all over again.” If such an outcome is perfectly acceptable to you, I would suggest you are lurking on the wrong site.
    You are correct to say that any ‘state of humanity’ report card would have much to be positive about – we have increased our population fifteen-fold in 500 years and now zoom round the world in a fortnight more than we did for all of our existence up to 1900. For the privileged societies that have escaped the Malthusian prediction of mass poverty, life expectancy has doubled and child mortality has reduced twenty-fold.
    These are astounding achievements but you seem to be content for the wheels to fall off our civilisation with the less privileged societies in the firing line for primary carnage. Why is this? Do you suffer from psychopathy or something?

    Comment by MARodger — 20 Aug 2013 @ 10:12 AM

  77. What is that sage advice every investor gets whenever they research places to plunk down their big bucks? Something like, “Past performance is no guarantee of future gains.” In other words, screw the irrational exuberance, Bubbles, use your head, break a sweat and drill down. It’s not just caveat emptor, it’s a good general principle.

    And hey, it’s not as though all that wonderful fossil fuel technology caused these problems in the first place. Pfft! Unintended consequences my arse! What me worry!

    I just love it when the armchair response to some problem is an airy, condescending “see, here’s what you do: solve it.” Gee, what an epiphany.

    One short take just for review:
    http://www.worldbank.org/en/news/feature/2012/11/18/Climate-change-report-warns-dramatically-warmer-world-this-century

    Comment by Radge Havers — 20 Aug 2013 @ 11:10 AM

  78. #71 Dave: Let’s stop wringing our hands and just adapt; why isn’t that an acceptable plan for the next 1000 years?

    Because, given abundant evidence and a soupcon of good judgment, we can see that mitigation (the usual jargon for avoiding the most severe climate changes) is far better than just adaptation, in that it will save and/or improve billions of human (not to mention other) lives.

    That’s why not.

    This is true whether or not you are sympathetic to the tone of some comments on a given website.

    Comment by Ric Merritt — 20 Aug 2013 @ 11:38 AM

  79. Dave, we aren’t ‘doomed’, and despite the fact that some further warming is inevitable, the amount of warming can still be strongly influenced by our decisions over the next couple of decades. There is time to have a significant impact on our future climate–and on the quality of life our kids and grandkids experience. I’ve written on that here:

    http://doc-snow.hubpages.com/hub/Climate-Change-How-Much-Time-Do-We-Have

    However, while carbon mitigation is obviously tough to sell, politically speaking, it pales in difficulty in doing actual planning and preparation for the sort of apocalypse you describe. (I thought you didn’t go for gloom and doom?)

    Much easier to avoid what can still be avoided, even if it involves working like hell.

    That said, there is certainly thought being given to the question of adaptation, and in fact adaptations are being made all the time. A very nice book length treatment is Amy Seidl’s “Finding Higher Ground”, which (by an amazing coincidence!) I have also written about:

    http://doc-snow.hubpages.com/hub/Finding-Higher-Ground-A-Summary-Review

    Comment by Kevin McKinney — 20 Aug 2013 @ 11:38 AM

  80. Dave, a “lurker” here:

    Habitability will be affected over time and we will respond over time. Less land mass, less food – less humans being born – and so on. Maybe we end up with a few human populations dotted around the globe post apocalypse – and then we start all over again.

    Why is that not an acceptable plan for the next few 1000 years.

    You can’t have been lurking here long, or you’d already know why your plan isn’t acceptable to many of the commenters here. It’s because your plan entails death and misery for billions of people! Dare I speak for many here who would forestall that scenario by any means necessary?

    Comment by Mal Adapted — 20 Aug 2013 @ 12:47 PM

  81. Trolling Daves misconception is his belief that the changes he envisions will take place over “the next few 1000 years“. Try the next few hundred years Dave, with the trajectory likely locked in within a few decades.

    Comment by flxible — 20 Aug 2013 @ 2:40 PM

  82. New Scientist plugging a report today that increased rainfall and flooding in Australia in 2010 involved so much water that sea level fell by 7mm.
    http://www.newscientist.com/article/dn24080-how-an-ocean-went-into-hiding-in-australia.html#.UhPNopK1GIo

    Got me thinking – if we set out to turn the Sahara into forest and arable land (which I’m guessing might be doable if the political will was there) how much might that affect sea level? how much carbon would be locked in?

    Prevention’s obviously better than cure, but if we need a cure, greening the Sahara seems like a better one than some I’ve heard suggested, like sulphur emissions or space parasols.

    Or not?

    Comment by rob — 20 Aug 2013 @ 3:34 PM

  83. But wait.

    We were talking about sea level rise, and this paper in particular.

    (If sea level rises, will red herring increase?)

    Comment by Hank Roberts — 20 Aug 2013 @ 3:42 PM

  84. We need to accept that we will NOT make any meaningful reduction in CO2 emissions, especially in the near term. The burning of fossil fuels is the economic basis for most all major economies. The statement, “We need to stop/change the burning of fossil fuels in the near term to prevent catastrophic change in the far future”, has been continuously stated for decades with no effect. Does anyone really think, Russia, Canada, United States, China, the Middle East, Brazil, etc. will significantly reduce the burning and/or exportation of fossil fuels? Humans will burn most all the economically feasible fossil fuels available as the immediate impacts are too great for any government to overcome. There are plenty of human nature studies to explain why we behave this way. So why yes, rational people have a hard time accepting @71 Dave’s statement of whatever is going to happen from significant increase in CO2/temperature is going to happen, even if it means wholesale destruction of the present human condition, he is most likely correct.

    I agree with @27 adelady’s view on the collapse of Antartic ice sheets. Open the door of a freezer (with no defroster) and watch it melt. It drips, drips , drips and then suddenly collapses when the adherence of the ice to the frame reaches a critical point.

    Comment by DHouck — 20 Aug 2013 @ 4:30 PM

  85. > I agree with @27 adelady’s view
    Oh dear, you realize she in 27 had just agreed with a scary story I had just made up a few posts earlier? People will believe improbable fiction if it’s scary enough, that was my point.

    Comment by Hank Roberts — 20 Aug 2013 @ 9:11 PM

  86. We need to accept that we will NOT make any meaningful reduction in CO2 emissions, especially in the near term.

    Ok, right, we should just give up, who needs reusable launch vehicles and electric cars, and that Mottness concept is just a bunch of liberal nonsense. Since we can’t see electrons and atoms we should just not try to put them together in clever ways. I’m with you, fossil fuels uber alles!

    1000 ppm here we come! Life is about commerce, and business! Yeah sure buddy.

    Comment by Thomas Lee Elifritz — 21 Aug 2013 @ 2:05 AM

  87. #84–“…has been continuously stated for decades with no effect.”

    Except that that’s not true. While we certainly are nowhere near where we need to be yet, things would have been worse still without the efforts that have been made.

    The EU is on track to over-achieve Kyoto emissions goals:

    http://ec.europa.eu/clima/policies/g-gas/index_en.htm

    Better yet, much of this comes from real structural change in the energy economies involved–Portugal’s solar and wind farms will be generating clean power for decades. Of course the German example is the leading one, with renewables accounting now for about a quarter of all electric generation, and rising rapidly–albeit at times rather chaotically as their ‘energiewende’ evolves.

    You point out that the EU’s emissions account for maybe 11% of the global total? True, but American emissions are falling as coal plants are taken out of service, and renewables are the largest category of new generation capacity. And China, the world’s biggest emitter, is adding renewable capacity faster than anyone–not surprisingly, given the shocking air-quality issue that they have created for themselves using coal.

    India, too, is moving aggressively to add solar, both central and distributed capacity. Coal isn’t serving them very well, either.

    Am I saying all is well? Certainly not. Emissions are far too high, the disinformation campaign continues to bamboozle people and blunt political will for change, technical and economic difficulties remain. At the end of the day, we’re still tracking closer to the higher emissions scenarios than the lower ones.

    But it’s still a horse race. Humanity still has a chance to show that it’s wiser than your average cancer cell–or, maybe more appositely, cyanobacterium.

    Comment by Kevin McKinney — 21 Aug 2013 @ 7:40 AM

  88. So are we agreed it was a good effective troll?
    He dragged his red herring through once.
    He got multiple replies.
    Took everyone completely off the topic.

    Ignores the scientists here to talk about their research.

    Can we please stop now and focus on the topic here?
    Please?

    Comment by Hank Roberts — 21 Aug 2013 @ 11:18 AM

  89. Give up Sacramento? Considering how far it is from the ocean that is truly a scary idea.

    Comment by Ken Carr — 21 Aug 2013 @ 12:04 PM

  90. Kevin #87

    True, but it is worth keeping in mind that global co2 emissions in 2011 were a record amount. Then 2012 exceeded 2011. I have read that 2013 is expected to set another record. Some place are getting better and some are getting worse. On the whole things are getting worse.

    Note that a major factor in the dropping US emissions is the increasing burning of natural gas. Recent studies have indicated that for every trillion cubic feet of gas produced another 10% is lost to the atmosphere. If we recalculated US emissions to include responsibility for that lost methane the figures might not look as good as they do. This methane lost during natural gas production is a global problem and it might not be being satisfactorily included in the global emission numbers either.

    Comment by JimD — 21 Aug 2013 @ 6:27 PM

  91. @89 – It’s not how far from the ocean Sacto is, it’s how far above that’s the rub, there’s a deep water port there at the confluence of 2 major rivers, Sacto has always been subject to flooding.

    Comment by flxible — 21 Aug 2013 @ 7:37 PM

  92. Maybe it would be a good idea to have an article/thread about the drawdown of CO2 emissions and where we currently stand on getting that accomplished. If you factor in the methane emissions from the production of natural gas where does that leave us? According to one of the videos that Hank posted on Unforced Variations, we have until about 2020 to keep global average temperature at or below 2C and even then it’s almost impossible according to that presentation. (The video I’m referring to is the one comparing 3 possible scenarios to ski slopes.)

    Comment by Chuck Hughes — 21 Aug 2013 @ 11:01 PM

  93. We are pushing increasing amounts of CO2 into the atmosphere each passing year.

    We are not reducing emissions no matter how many people assert we are.

    I have no doubt that the majority of people on here, who are predicting an apocalyptic future for mankind unless we change our habits, have personally got rid of their gas guzzling cars and wouldn’t even consider using aircraft to get around. I am sure they will have made their houses as energy efficient as possible and don’t use things like air conditioning unless they are generating the power from renewables. I mean if people on here weren’t prepared to do this, people who know the future disastrous consequences of rampant energy use, how could you expect other people to do so who are not so aware of this or who even are not so convinced of such future events.

    I mean what was predicted fir the 21sr century at the end of the last century. It was predicted that even if we stopped producing CO2 immediately we would have substantial ‘pipeline’ heating to deal with. Continuing at the same rate was going to cause huge further increases in addition to this.

    We did not stop we have continued to push it out at an ever increasing rate
    Indeed we have emitted more than 30% of the whole total of man’s emissions since the industrial revolution.

    Now look at the disaster that is upon us, look at what has happened to temperatures since the start of this century, look and weep.

    Alan

    Comment by Alan Millar — 22 Aug 2013 @ 11:05 AM

  94. Jan Galkowski says: “Were we to get CO2 back to 270ppm within 50 – 100 year” … Not sure but it sounds like Killian may be confusing emissions with accumulation.

    Nope.

    …drawing down CO2 means carbon dioxide REMOVAL

    Yup.

    For global deployment and assuming it can be done at all, that’s priced at trillions of U.S. dollars per annum.

    Nope. Just one example: It don’t take trillions if we don’t keep doing stupid stuff and choose to do intelligent stuff instead.

    Nobody wants to hear it, but the greatest part of the answer is to use a whole lot less.

    45 bibasir says: Killian @18 — Reducing CO2 to pre-industrial concentrations would eventually lead to the formation of as much ice as was present then.

    I’m not so sure about that. That ice was formed during the last glacier period. It has been melting for the last 11,000 years, so why do you think it would reform?

    Shouldn’t be hard to figure out at what temp level reforming would occur and design accordingly. Determine a number, design to it.

    51 David B. Benson says, Killian @27 — Ice sheets and glaciers grow snowflake by snowflake but melt everywhere lower than the freezing line: a long time to reform the ice mass. Think in units of centuries.

    Yes, obviously. The more interesting question is at what level we can arrest it, and how quickly given reaching a certain level of CO2 (or CO2e). Plan to that since, as you point out, rebuilding the ice sheets takes time.

    82 rob says, New Scientist plugging a report today that increased rainfall and flooding in Australia in 2010 involved so much water that sea level fell by 7mm.

    http://www.newscientist.com/article/dn24080-how-an-ocean-went-into-hiding-in-australia.html#.UhPNopK1GIo

    Got me thinking – if we set out to turn the Sahara into forest and arable land (which I’m guessing might be doable if the political will was there) how much might that affect sea level? how much carbon would be locked in?

    Prevention’s obviously better than cure, but if we need a cure, greening the Sahara seems like a better one than some I’ve heard suggested, like sulphur emissions or space parasols.

    Or not?

    Each 1% addition of carbon to soils = a 1.5% gain in water holding capacity, so, yes, build soils and you reduce sea level. One square meter of 5% organic material/carbon = something like 130 gallons… or is it pounds?… mind like a sieve, I tell ya… of water. (Sorry, don’t have Brad Lancaster’s books or the Designers Manual with me at the moment.)

    An interesting story out of Australia about scientists figuring out stuff in the Designers Manual… 30+ years later: Ain’t that soil fascinating? You’d be amazed at the problems we solve by just building healthy soils…

    92 Chuck Hughes says, Maybe it would be a good idea to have an article/thread about the drawdown of CO2 emissions and where we currently stand on getting that accomplished. If you factor in the methane emissions from the production of natural gas where does that leave us? According to one of the videos that Hank posted on Unforced Variations, we have until about 2020 to keep global average temperature at or below 2C and even then it’s almost impossible according to that presentation. (The video I’m referring to is the one comparing 3 possible scenarios to ski slopes.)

    This will only be of much use if the article looks at all “technologies” and not just “tech” and not just what most here would consider “tech.” There are people growing stuff all over this planet that exceeds what the scientific community accepts as possible or probable, and sequestering carbon. Where Nature creates inches of soil over hundreds or thousands of years, we can speed up succession to build inches in years. That’s a lot of food security, SLR management, flood management, ecosystem stabilization/creation/recreationb, etc., etc.

    While most want to talk to an engineer to solve our problems, you should be talking to regenerative farmers.

    Comment by Killian — 22 Aug 2013 @ 12:46 PM

  95. Hmmmm. Never considered myself a troll but OK. When the world CO2 concentrations either flatten out or go down, let me know. Until then, we are on track for a C02 concentrations of 800 ppm or more by end of century. You can talk all you want about what might be from all the current efforts, etc. but until it happens, I’m not with you. Not that I wouldn’t want to be.

    Comment by Dhouck — 22 Aug 2013 @ 9:30 PM

  96. Alan Millar @93.
    Your comment – “Indeed we have emitted more than 30% of the whole total of man’s emissions since the industrial revolution.” Is this based on some reference or did it sadly suffer a typo or a fact-mash? Of course we all make mistakes but I firmly believe that one useful development to combat climate change would be better lighting beneath bridges. The level of competence within the troll community since the start of this century has become unbelievably bad, although truth be told, my personal response is often one of amusement rather than sorrow.

    Comment by MA Rodger — 23 Aug 2013 @ 4:10 AM

  97. #93–“We are not reducing emissions…” Some significant numbers of us are, and there is good reason to think that that trend will continue. And that is an existence theorem for everyone else.

    #95–“…what might be from all the current efforts, etc. but until it happens…” But what I talked about has happened, and continues to happen. Presumably you are with alan @ 93 in wishing to see results at the global level–and quite right, of course, the atmosphere doesn’t ‘care’ if a kilo of CO2 is American, Chinese or Nigerian–but recall that we started with ‘has had no effect.’

    I’m “with you” that the effect so far is insufficient. But nevertheless it exists, and has some promise at least. I mention it again, despite Hank’s point that we are, once again, OT, because despair is pointless. It may feel good in a perverse sort of way–it’s amazing how many folks seem to embrace it now on various news threads, BW; lots of commenters on various venues, who may barely be able to spell ‘tipping point,’ seem quite sure they know we’ve passed ‘it’–but despair really doesn’t enhance the effectiveness of the message (or messenger).

    But I actually do have a sea level question. It seems from a line in the abstract of Dr. Leverman’s PNAS study, “As a consequence we are committed to a sea-level rise of approximately 2.3 m °C−1 within the next 2,000 y,” that the relevant time-frame is two millennia. Was that the actual equilibrium time for SLR, or was that the study’s end point, and thus some sort of lower limit–to the linear relationship between temperature and SLR derived in the paper, at least, if not to SLR itself?

    Comment by Kevin McKinney — 23 Aug 2013 @ 8:01 AM

  98. In re reducing emissions, this was a valuable lesson for me (a repeat from Unforced V) and I think it involves some hard factual thinking, whether or not you accept it:
    http://vimeo.com/7081438

    It is confusing that as in dieting, we need first to slow the acceleration, then stop, then reduce. The scientific bods have got this well under their hats, but the rest of us need to remember that slowing emissions does not reduce the cumulative total. I’ve never completely understood the lifetime of CO2, which in various ways is said to be 100 or 1000 years – but don’t really need to know – just that it’s persistent and the effect is delayed, so we have already put ourselves in jeopardy. Action yesterday is what is needed, but our marketing expansion model is doing the reverse.

    Comment by Susan Anderson — 23 Aug 2013 @ 10:50 AM

  99. > despair is pointless
    Despair is a tactic: “Delay is the deadliest form of denial.”
    — C. Northkote Parkinson

    Agree with Kevin’s question about 2000 year timeline used, whether that’s a limit on the study, or on how nature’s projected to handle the CO2 if we continue down this path.

    Comment by Hank Roberts — 23 Aug 2013 @ 12:29 PM

  100. As a consequence we are committed to a sea-level rise of approximately 2.3 m °C−1 within the next 2,000 y

    Those numbers are insanely optimistic and I don’t believe them for a second.

    Comment by Thomas Lee Elifritz — 23 Aug 2013 @ 1:35 PM

  101. Comment by MA Rodger — 23 Aug 2013 @ 4:10 AM

    Well here is a graphical view of total emissions since 1751.

    http://www.earth-policy.org/indicators/C52

    I think it demonstrates very clearly the significant percentage of man’s total emissions that have been issued this century. You can work out the exact percentage from the data if you wish.

    Like I said this basically uncontrolled continuation of our emissions this century must have lead to the changes in global temperatures that have happened during the same period. This is surely in line with theory which inextricably links the two phenomena together. Or are you suggesting some other linkage?

    Alan

    Comment by Alan Millar — 23 Aug 2013 @ 1:38 PM

  102. Comment by MA Rodger — 23 Aug 2013 @ 4:10 AM

    Well here is a graphical view of total emissions since 1751.

    http://www.earth-policy.org/indicators/C52

    I think it demonstrates very clearly the significant percentage of man’s total emissions that have been issued this century. You can work out the exact percentage from the data if you wish.

    Like I said this basically uncontrolled continuation of our emissions this century must have lead to the changes in global temperatures that have happened during the same period. This is surely in line with theory which inextricably links the two phenomena together.
    Or are you suggesting some other linkage?

    Alan

    Comment by Alan Millar — 23 Aug 2013 @ 1:39 PM

  103. for MA Rodger and Alan Millar, you’re both right.

    starting at
    http://www.realclimate.org/index.php/archives/2013/08/the-inevitability-of-sea-level-rise/comment-page-2/#comment-404645

    The 30 percent figure is CO2 increase in the atmosphere since the beginning of the industrial revolution: https://www.google.com/search?q=industrial+revolution+co2+30+percent

    Yes, human activity started boosting CO2 before the industrial revolution, but that was not -fossil- carbon; that was from forests and fields and topsoil and peat and whale oil — everything we ate, burned, and wasted — changing where the biosphere held carbon.

    That was being handled by natural cycling, dissolved in the ocean, and slowly increasing CO2 in the atmosphere.

    Then — industrial revolution — we started burning coal and fossil oil and dumping fossil methane into the air.

    Biogeochemical cycling has handled half of -that- as well. So far.

    Comment by Hank Roberts — 23 Aug 2013 @ 3:23 PM

  104. Alan Millar:

    I mean if people on here weren’t prepared to do this, people who know the future disastrous consequences of rampant energy use, how could you expect other people to do so who are not so aware of this or who even are not so convinced of such future events.

    Why, through a carbon tax, or some method of pricing fossil fuels to internalize their full costs. That way wouldn’t require other people to be aware or convinced of the consequences of rampant energy use, as long as government taxing authority can be asserted. Once the full costs are internalized, the invisible hand can take over.

    Unless you think that the problem can be solved through individual efforts. If so, I presume you’re unacquainted with the Tragedy of the Commons, of which AGW is a classic example.

    Comment by Mal Adapted — 23 Aug 2013 @ 3:35 PM

  105. Comment by Mal Adapted — 23 Aug 2013 @ 3:35 PM

    So people who are absolutely convinced of a coming catastrophe and are evangelical about the need to change behaviours, will actually only change their personal behaviour if forced to by taxation? The justification for this being that, why should they change if others are unwilling and they cannot do it on their own.

    Do you agree with this viewpoint?

    It doesn’t seem to me to be the most inspiring or convincing message to the less convinced.

    Alan

    Comment by Alan Millar — 23 Aug 2013 @ 6:23 PM

  106. > Do you agree with this viewpoint?

    Yes, I think sea level rise is definitely going to happen.
    Believe it or not.

    Comment by Hank Roberts — 23 Aug 2013 @ 10:14 PM

  107. We seem to be mired in political inaction. How long will this continue? It may be a little off topic but it does mention sea level rise.

    http://consortiumnews.com/2013/08/20/will-the-american-right-kill-us-all/

    Comment by Chuck Hughes — 24 Aug 2013 @ 4:01 AM

  108. Hi Hank Roberts @103.
    I did wonder if our guest Mr Millar was thinking atmospheric increases while saying emissions. But his comment @101 shows he didn’t (or doesn’t) mean that at all.
    As for when to place the “Industrial Revolution” the common time is the eighteenth century. Of course that isn’t very exact. I like the idea of timing it to the coke-powered iron production by Abraham Darby in Coalbrookedale, he being the first person (outside China) to dream up uses for fossil fuels that weren’t just cooking or heating houses. That would put the revolution as happening on 10th January 1709. But in climatology 1750 is the year used (eg by IPCC).
    As for the the 30% figure (which is as you demonstrated still encountered); it is a tad behind the times. (I do get the strong impression that our Mr Millar is living in the past.) A more up-to-date figure would be 395/280 = 41%.

    Comment by MA Rodger — 24 Aug 2013 @ 4:49 AM

  109. Alan Millar @101.

    You wrote @93 “Indeed we have emitted more than 30% of the whole total of man’s emissions since the industrial revolution.” This was ambiguously worded so it is helpful that you comment now (at last) allows us to know what you are on about.
    I can thus tell you that you are wrong. Using the data you point to, emissions this century (even if you include the year 2000) are not “more than 30%” as you claim, and the ratio will be reduced further if emissions from changing land use are also accounted for.

    The word “inextricable” is not usually found within scientific statements. You are claiming that a “basically uncontrolled continuation of our emissions this century” is “inextricably” linked by theory with the “changes in global temperatures that have happened during the same period.” I have to say this is a theory of which I am unaware. And I find that strange as I usually keep abreast of developments within climate science.
    So, far from “suggesting some other linkage,” I am entirely ignorant of your inextricable link or of the theory from which it derives.
    Perhaps you could explain this theory of yours or provide a reference to it.

    Comment by MA Rodger — 24 Aug 2013 @ 4:55 AM

  110. So what works better, top-down or bottom-up solutions; is that the question?

    IMO we tend to romanticize grass-roots activism, which under special circumstances can organize to effect. But everything in society is systemic. The libertarian notion that radical individualism, given sufficient cheerleading, will always automagically generate some kind of utopia, never a swamp, is suspect. It seems about as likely as throwing a bunch of nuts and bolts into a box and expecting it to go out and mow the lawn.

    If AGW is one inconvenient truth, two more are how necessary good government is to assist in solving large, complicated problems and how it gets broken and bought out by corrupt interests.

    Comment by Radge Havers — 24 Aug 2013 @ 10:30 AM

  111. Killian wrote (#94): “Nobody wants to hear it, but the greatest part of the answer is to use a whole lot less.”

    According to the latest analysis from the Lawrence Livermore National Laboratory, “the U.S. is just 39 percent energy efficient … more than half (61 percent) of the energy that flows through our economy is ultimately wasted.”

    Which means that we in the USA could cut our total energy consumption by more than half, with NO reduction in our “use” of the services that energy provides — simply by eliminating outright waste.

    And keep in mind that the vast solar and wind energy resources of the USA are much more than sufficient to produce ALL the energy that we currently consume.

    GHG emissions from energy generation are not the whole problem, but they are a huge part of the problem, and the reality is that they can be rather easily eliminated by making efficient use of available carbon-free energy sources, with no need whatsoever to resort to extremes of austerity in our use of energy.

    Comment by SecularAnimist — 24 Aug 2013 @ 11:42 AM

  112. > Perhaps you could explain this theory of yours

    Elsewhere please.
    You guys are tag-teaming distraction from the topic, a specific paper with the author here to take questions.

    Leave off so we hear more from the real scientists, eh?

    (why yes, I am the cranky you-kids-offa-my-lawn type, why do you ask?)

    Comment by Hank Roberts — 24 Aug 2013 @ 1:04 PM

  113. Sea Level Rise Found to Cause Slope Collapse, Tsunamis, Methane Release Link

    And regarding messaging of outcomes: Climate Change Alarm is Needed and Climate Scientists Aren’t Sounding it Loud Enough Link

    Comment by prokaryotes — 24 Aug 2013 @ 1:07 PM

  114. Alan Millar, most recently:

    So people who are absolutely convinced of a coming catastrophe and are evangelical about the need to change behaviours, will actually only change their personal behaviour if forced to by taxation?

    Alan Millar, previously:

    I have no doubt that the majority of people on here, who are predicting an apocalyptic future for mankind unless we change our habits, have personally got rid of their gas guzzling cars and wouldn’t even consider using aircraft to get around. I am sure they will have made their houses as energy efficient as possible and don’t use things like air conditioning unless they are generating the power from renewables.

    You are likely correct about the majority of people here, if by “here” you mean frequent commenters on this blog. Do you really not understand that even if all RealClimate commenters were to model the needed behavioural changes conscientiously, the future would be no less apocalyptic if the unconvinced (whether because of ignorance or active denial) don’t change as well? Do you think that paying a carbon tax is worse than global climate catastrophe? I’m afraid you’ll need to convince us of that.

    Comment by Mal Adapted — 24 Aug 2013 @ 1:12 PM

  115. Many comments here belong in the unforced variations thread.

    Let me return to the Leverman paper.

    1) I see that they use a model by Pollard for Antarctica. As I uncerstand it, that model has no basal hydrology. But we see sub ice water in many places in Antarctica. Is this a problem for the model ?

    2) Was there any hysteresis seen in the Greenland or Antarctica models ?

    sidd

    Comment by sidd — 24 Aug 2013 @ 3:16 PM

  116. 1. While a bit too cheery, I think this is one of the cheerier articles I have read in a long time. I think it is not an accident that utilities are now desperately trying to claw back on reverse metering and any subsidies.
    http://www.csmonitor.com/Business/In-Gear/2013/0602/Will-solar-power-kill-utility-companies-They-think-so.

    2. On the emissions despair motif (waaaa–we can’t do anything but die), the IPCC has modelled various emission scenarios for 20 years. What we do, individually and by policy does matter. And one would opine that if solar and wind options are driven down in cost by 1st world adoption, 2nd world adoption will quickly follow. It is no accident that China is rather desperately incentivizing both solar and wind.

    Comment by Robj — 24 Aug 2013 @ 4:30 PM

  117. This is a response for various posts by Alan Miller-

    For some of us the objective is to preserve as much of our present ‘behavior’ as possible. There are simply not enough of us to create a market that someone will respond to. Carbon taxes or cap-and-trade are means of creating demand that results in reduced carbon footprint goods and services.

    Comment by Dave123 — 25 Aug 2013 @ 5:07 AM

  118. I think we have to look on this as a long term strategy to gain a permanent republican majority. The takings clause of the Constitution requires just compensation for use of eminent domain. So it would be expensive to eliminate the urban democratic districts just by taking them. But property law says that land lost to permanent inundation is simply no longer property. Thus, conversion of these districts to federal waters can occur with no compensation at all. House congressional seats long held by democrats can be eliminated and republicans can gain a permanent advantage. While some republican coastal second homes may be lost as well, it won’t be a loss in the district in which the republicans vote.

    Comment by Chris Dudley — 26 Aug 2013 @ 6:48 AM

  119. #118–Really? One hopes the voters themselves won’t be inundated, in which case they’ll just change voting patterns in other districts.

    Or was that a smile I didn’t ‘see?’

    Comment by Kevin McKinney — 26 Aug 2013 @ 12:43 PM

  120. I live in the Lowlands near the sea in the West of Europe. My ancesters (German tribes that had replaced the Romans) invented flood protection in the 9th century.
    As a results, their descendents were able to deal with all the sea level changes from the early middleages until now (Dunkirk transgressions and regression afterwards) . We have the best nautical engineers and the best dredging companies in the world. My homeland is extremely vulnerable to climate change, yet we have been able to maintain our high standard of living for more than thousand years. We do not fear the future as we are well prepared for sea level changed. And we can help the rest of the world with our advanced floodprotection technology.
    Optimism is a moral duty (Popper).

    Comment by Filip Hondekyn — 27 Aug 2013 @ 2:07 AM

  121. Optimism may be a duty, but realism must be a prerequisite to optimism.

    Comment by Ray Ladbury — 27 Aug 2013 @ 10:06 AM

  122. As noted in the post, warming and SLR have a long lifetime. In human terms, it will certainly be multi-generational. As in any war, some locations will be saved and other sacrificed early on. Some locations will, over time, receive devastating assaults and others will succumb to the slow ravages of wind and water damage and other relentless environmental insults. The outcome will be an influx of refugees moving to higher ground. These refugees will be largely dependent on Federal and State support. Staying within the context of your argument, this is where the on-going expenses will be incurred. I can’t imagine a scenario for the US where mitigation will be more expensive than remediation.

    Comment by Eric Rowland — 27 Aug 2013 @ 2:49 PM

  123. “Pessimism of the intellect, optimism of the will.” (Gramsci)

    Though I admit that the latter is getting harder to muster.

    Protecting the Lowlands during relatively stable sea level conditions, impressive as that has been, is a completely different thing from protecting them (and all other near or below sea level areas) from ever increasing sea levels and increasingly stormy seas.

    (On the other hand, the apparently ever-optimistic reCaptcha says: arranged astypedZ)

    Comment by wili — 27 Aug 2013 @ 3:27 PM

  124. As in any war, some locations will be saved and other sacrificed early on. Some locations will, over time, receive devastating assaults and others will succumb to the slow ravages of wind and water damage and other relentless environmental insults.

    It also means that land is flooded, land is lost to coastal erosion – dependent on the new SLR regime. This means that vast amounts of possible new environmental contamination will occur when modern human settlements become lost to the sea. The ecosystem response will likely contribute to growing ocean dead zones and could induce another feedback from increased decomposition rates and the availability of higher amounts of organic content. For instance, just to visualize one serious implication means to understand how we plan to bring nuclear power plants to higher grounds.

    Comment by prokaryotes — 27 Aug 2013 @ 10:50 PM

  125. @124 It used to be that floods were water emergencies. Now they’re one-way runaway combinatorial toxicity events–and becoming more so.

    Comment by patrick — 28 Aug 2013 @ 2:28 AM

  126. For instance, just to visualize one serious implication means to understand how we plan to bring nuclear power plants to higher grounds.

    I can’t see this, at least, being much of a problem. Can any operating nuclear reactor not handle a 3′ rise in sea level? Will any existing nuclear reactors still be operating ~85 years from now when the sea will have risen 3’? It’s a very slow process, so we have plenty of time for planning about this.

    Comment by Greg Simpson — 28 Aug 2013 @ 2:44 AM

  127. Greg Simpson

    I can’t see this, at least, being much of a problem. Can any operating nuclear reactor not handle a 3′ rise in sea level? Will any existing nuclear reactors still be operating ~85 years from now when the sea will have risen 3′? It’s a very slow process, so we have plenty of time for planning about this.

    Here are 2 articles from last year on this topic Sea Level Rise Brings Added Risks to Coastal Nuclear Plants and Nuclear Power Plant Flood Risk: Sandy Was Just a Warm-Up

    Not sure where you get the 3′ increase but projected are up to above 2 meters (till 2100), which does not include potential non linear developments. Further is SLR not uniform, which means that in areas such as the US East Coast, SLR is 25% more pronounce.

    Comment by prokaryotes — 28 Aug 2013 @ 7:53 AM

  128. In the scheme of things, how important is the Tower of London? Is affection for a medieval monument the criterion for societal decisions of this magnitude?

    I can do without Miami, assuming that the real estate moguls don’t see the writing on the wall and move their investments elsewhere, i.e. inland, which would, incidentally, preserve their lock on the beachfront.

    Society makes decisions, without acknowledging them, about future generations all the time. Sometimes cities die because of them: take a look at Detroit, MI. It’s not all that unusual in the history of civilization. Nor has it brought on the end of civilization.

    None of this is intended as a critique of your scientific arguments, but conclusions regarding politics you draw from them are not based in any recognition of the history and development of civilization and how it comes about. You speak in the tone of Jor-El before the catastrophe, or Hari Seldon of the Foundation Series: nobody heeds your prescient warnings! Those are fictional creations – get real.

    Comment by Lichanos — 28 Aug 2013 @ 10:08 AM

  129. Oh, forgot this too – most of NYC is well above the present or projected sea level. It’s only those portions of the city on made land that we we would lose.

    Comment by Lichanos — 28 Aug 2013 @ 10:12 AM

  130. > robertscribbler, recommended (or perhaps merely pointed to) by prokaryotes

    says
    > the shallow East Siberian Arctic Shelf …. structures
    > in these regions are already emitting …. methane ….

    Good so far

    > … from undersea hydrate stores.

    Citation needed; he’s still assuming hypothetical shallow water hydrates to make the scary story hugely more scary than the science supports.

    Yes methane is a big scary story.
    No, it’s not 160x scarier than science supports.
    It’s puny next to coal.

    Don’t distract people from the real problem. Dammit.

    Problem is — being enthusiastic, sincerely caring, utterly convinced about the world’s woes and the need to fix the problem — isn’t enough, if you want people to trust you as a reliable source of good information.

    Having your heart in the right place doesn’t improve how you think.

    You need to check the stuff you point to, not just point to it and say, awesome, look, if that were true it’d be just awful.

    Reality is scary enough.

    We need facts.

    Comment by Hank Roberts — 28 Aug 2013 @ 10:25 AM

  131. Greg Simpson: Can any operating nuclear reactor not handle a 3′ rise in sea level?

    As long as there’s no weather, absolutely. Assuming rest of geophysics comes to a screeching halt there’s nothing to worry over.

    Comment by Doug Bostrom — 28 Aug 2013 @ 6:35 PM

  132. A 28 min interview a couple of day’s back (BBCi link here – may be restricted to UK) on BBC Radio 4’s ‘The Life Scientific’ with Jo Haigh of Imperial College, an atmospheric physicist. How she’d cope with deniers like Lichanos @128/129 (and she is quite strong on using that term “denier”) would appear to be ‘politely’. Perhaps we should accept that when deniers like Lichanos at least admit in argument that SLR is happening, that is a small step in the right direction.

    “And the idea that the IPCC is some sort of consensus body of mad green scientists who are all trying to, um, have their own agenda, er, work through government or something I don’t know, is quite ludicrous. I mean, you know what its like when you put a load of scientists together in a room, they are not going to decide to agree with each other together. In fact they are each going to decide to be clever and decide to disagree with each other. So consensus is very very hard to achieve and the fact that they come up with some sort of general agreement means you can be pretty sure that that’s been worked through well.”
    Q- What is the current consensus then amongst scientists about how are climate is changing? Are we doing enough to avert a potential disaster in years to come?
    A – No. Not at all. No. Precious little. All the science shows that unless we do something more radical the temperature is going to carry on increasing.

    Comment by MA Rodger — 29 Aug 2013 @ 3:52 AM

  133. I wrote a comment @71 about 10 days ago and hadn’t revisited until just now. I read that some identify me as a Troll, some dismiss me and some responded to at least part of what I was trying to say.

    My point, however inadequately put, was to suggest that there is inevitability about changes to the climate that are coming – that we have/are, in actuality, done/doing nothing that will change that.

    Does anyone here believe that CO2 ppm is going to reduce in the next 50-100 years?? Does anyone believe that, globally, the initiatives agreed and undertaken are actually going to reduce CO2 in that period?

    Unless China, India, Brazil, etc get on board and reduce their CO2 production then, in reality, the initiatives being implemented by “the West” will not contribute to an overall reduction. Does anyone disagree with that? Does anyone think that’s going to happen?

    I am not saying we shouldn’t do everything we can (in the west) but it will never, realistically, be enough.

    Just so you know, I haven’t been on an aeroplane for over 5 years, I drive less than 2000 miles a year. I am a vegetarian and eat less than 1500 calories per day. I recycle as much as possible and produce very little rubbish or food waste. My wife and I have produced two kids – which will replace my wife and I when we are gone. Any of you have more than two kids? I am happy to put my personal carbon footprint up against any contributor/commentor on this site.

    And that’s the point isn’t it. It doesn’t matter (in reality) what I do – its what the rest of you do – and you aint doing enough to prevent the inevitable.

    So, coming back to my point, if we believe that 2 degrees of warming is now “locked in” in the next 100 years – what should we be doing now to deal with the issues that we result from that predetermined warming? Which Islands are going to go under and what are we going to do with that population? Where should we stop allowing building development near threatened coastlines? etc etc. Alternatively, where, around the world, are we going to build coastal or flood defenses that will cope with the predicted sea level rise? Where will water and food availability be problematic and what are we going to do about that. Will there be areas with greater water and food production capability?

    As an aside, and hopefully an observation of the blindingly obvious, it is clear that the single factor that is most responsible for AGW – is the growth in the human population here on earth! If our population was where it was 50 years ago – then AGW would probably not be an issue. The estimated, continuing rapid rise in the human population is the single main factor that has/will cause the problems envisaged.

    So, here we go. What would be the affect of limiting every person on the planet to having one child (for clarity, that’s two per couple). What would that achieve? Is that a more achievable goal than other initiatives? … and so on.

    Comment by Dave — 29 Aug 2013 @ 4:12 AM

  134. Miles et al: doi:10.1038/nature12382

    The biggest player, EAIS, more labile than thought.

    ” … the vulnerability of large parts of the EAIS margin requires urgent reassessment.”

    Comment by sidd — 29 Aug 2013 @ 8:28 AM

  135. Lichanos wrote: “most of NYC is well above the present or projected sea level. It’s only those portions of the city on made land that we we would lose”

    If the New York City sewer system is flooded and eight million people cannot flush their toilets, the city is uninhabitable.

    Comment by SecularAnimist — 29 Aug 2013 @ 10:48 AM

  136. What would be the affect of limiting every person on the planet to having one child (for clarity, that’s two per couple).
    Do the math, 2+2 doesn’t = 2. There are many living humans with grandchildren and great-grandchildren, and even great-great-grandchildren. Your 2 children will be having children long before you and your spouse are dead, and count on those grandchildren having grandchildren soon after your demise, if not before. The only way to stop population growth [as China has found] is to stop reproducing. So in reality, it does matter what you do, your ‘footprint’ includes adding more humans to the current population, which you rightly perceive as the root of the problem.

    Comment by flxible — 29 Aug 2013 @ 7:27 PM

  137. …only those portions…

    “Only” is like “just.” Four letters to cover up what we don’t really want to think about.

    Comment by Doug Bostrom — 29 Aug 2013 @ 8:48 PM

  138. “Protecting the Lowlands during relatively stable sea level conditions…”. Sea level conditions of the North Sea have never been stable, transgressions, regression and floodings have repeatedly caused massive damage in known history. Read about “Floods in the Netherlands” and “the Dunkirk Transgressions”. Cities and villages disappeared in the sea, others lost their connection to the sea and became economically irrelevant. That’s why flood protection is omnipresent in urban developments near the sea since more than thousand years. “Open” cities such as New York are unthinkable in the Lowlands.

    Comment by Filip Hondekyn — 30 Aug 2013 @ 9:40 AM

  139. Dave @133
    You are presenting the most bizarre ideas here. And they are also way off topic, although you are not alone in that on this thread.

    You assert that is “blindingly obvious” that AGW can be blamed on population growth, indeed the “continuing rapid rise in the human population is the single main factor that has/will cause the problems envisaged,” having previously pointed the finger at “China, India, Brazil, etc” as offenders who will blow all chances of sorting AGW if they don’t “get on board and cut their CO2 production”.

    It is true that if there were 700 million humans and not 7 billion of us, we would have to be busier burning fossil fuels to do a proper job with achieving AGW. But beyond the theoretical, this is hardily a useful idea. And then to suggest that we Westerners are not the true offenders in all this – that is a rather distasteful idea, mainly because it is so untrue.

    If you take the historical cumulative emissions for each country in the world (Gapminder is one source.) and take the 16 top offenders, 4 of them are your offending non-Western countries with bulging populations. They are responsible for 16% of all historical CO2 emissions and today have a combined population of 2.6 billion.
    The other 12 countries are Western (if you can include Russia & Japan in such a description) responsible for 63% of all historical CO2 emissions with a combined population of 970 million. The top dog in all this is the good old US of A (31% missions all on their lonesome) with the good old Brits and the Belgians not far behind in per capita terms.

    The emissions that drive AGW are not a result of population, or of rising population but a result of high fossil fuel use, a practice at which us Westerners need no lessons from non-Western societies. We have the hang of that already. And when we eventually begin to significantly decarbonise our society, the non-Western world will no doubt be following close behind.

    Comment by MA Rodger — 30 Aug 2013 @ 9:50 AM

  140. flxible – the replacement fertility rate is generally accepted to be a bit over 2 births per woman per lifetime (the expectation that over large numbers of births, close to one of those will be a girl).

    “per couple” doesn’t really matter, it’s the fertility rate per woman that matters, but when a couple is together for their reproductive life and have two kids, it works out to be the same.

    The fact that kids have kids before parents die etc etc affects how long it takes for equilibrium to be reached, that’s all.

    The same principles apply to other species and is a rather basic element of population ecology.

    Comment by dhogaza — 30 Aug 2013 @ 12:13 PM

  141. flxible, in response to Dave:

    So in reality, it does matter what you do, your ‘footprint’ includes adding more humans to the current population.

    And those humans, your offspring, will each have their own footprints, as will their offspring, on into the future. The discounted present value of all those future footprints must be charged to your own. Whereas the footprint of a childless person declines to zero on that person’s death.

    While I’m at it, why does anyone think their genes are worth reproducing, anyway?

    Comment by Mal Adapted — 30 Aug 2013 @ 1:21 PM

  142. dhogaza, Note Mal Adapteds elaboration – and note that although China has had a “one child” policy for 30 years [for some of their populace], the population there has not reached “equilibrium” yet, it is still growing. The point is ecology involves more than population numbers, those numbers are not ecologically sustainable now, and even less so as we go forward.

    Comment by flxible — 30 Aug 2013 @ 5:01 PM

  143. 140 dhogaza said, “The fact that kids have kids before parents die etc etc affects how long it takes for equilibrium to be reached, that’s all.”

    Not in this case. Human life spans are increasing. I’ve read that the first person to live to 200 has probably already been born. Double life span and you double population. Can you say 15 billion?

    Comment by Jim Larsen — 30 Aug 2013 @ 7:32 PM

  144. #133–Dave, I don’t think anyone here thinks that adaptation won’t be (or isn’t) necessary. But it’s also not sufficient. Mitigation *has* to happen. And yes, I believe that it will happen–though how soon, how much, and how adequate remain open questions. (Indeed, as I indicated in my original response, I believe it is happening now, in incomplete but meaningful ways.)

    And, for what it is worth, I disagree that “the single factor that is most responsible for AGW – is the growth in the human population…” The growth of population is enabled–ie., partly caused–by the the burning of fossil fuels. And though population growth does factor into ecological footprint, it does not primarily drive it.

    Consider China: population growth has been slowing during the last couple of decades–precisely the period during which and GDP and GHG emissions have been surging.

    http://www.data360.org/dsg.aspx?Data_Set_Group_Id=201

    “What would be the affect of limiting every person on the planet to having one child (for clarity, that’s two per couple). What would that achieve?”

    Well, if China’s experience is a guide, and considering the above graph and the fact that ‘one child’ was mandated in 1979, to a reasonable approximation, we’d see a stable population in about 40 years, one about 40% higher than today. (Of course, China excluded!)

    “Is that a more achievable goal than other initiatives?”

    I doubt it, but it’s far too late in any case.

    Comment by Kevin McKinney — 31 Aug 2013 @ 10:51 AM

  145. > human life spans are increasing
    On average, yes — but maximum possible life span for an individual?

    Comment by Hank Roberts — 31 Aug 2013 @ 1:00 PM

  146. Re- Comment by Jim Larsen — 30 Aug 2013 @ 7:32 PM

    “I’ve read that the first person to live to 200 has probably already been born.”

    Where did you read this? Science fiction is not a good basis for environmental and social planning.

    Steve

    Comment by Steve Fish — 31 Aug 2013 @ 3:35 PM

  147. Looking at all the off topic discussion here and wondering if it would be out of order for this amateur to weigh in, instead I thought I would ask if anyone has addressed or is thinking about this news:

    http://www.climatecentral.org/news/newly-discovered-greenland-mega-canyon-sends-water-to-the-sea-16415
    (h/t Tenney Naumer)
    “Greenland “Mega Canyon” Sends Water to the Sea” (nice graphic)

    (Being a secondary reporter mostly for laypeople, ClimateCentral of course provides the original:
    http://www.sciencemag.org/content/341/6149/997

    Though I kind of knew about Greenland’s topography, this one gave me furiously to think.

    Comment by Susan Anderson — 31 Aug 2013 @ 7:50 PM

  148. Re. #135 from secular animist:

    Would the entire sewer system be flooded? I don’t think so, and the sewers of NYC are something I know a lot about. Don’t you think we could work out a few adaptations in the hundreds or thousands of years the author allows us?

    This is a fine example of the limited value of much scenario planning that passes for science these days. Sure, it would all be better if we could avoid the problem, but let usbe realistic…here at REALclimate.org.

    Comment by Lichanos — 1 Sep 2013 @ 10:35 AM

  149. > likely to have influenced basal water flow
    > from the ice sheet interior to the margin.

    I wonder if the canyon’s got a deep opening into the Arctic Ocean.
    Anyone looking for outflowing fresh water deep under the icecap there?

    Comment by Hank Roberts — 1 Sep 2013 @ 10:41 AM

  150. Dave@133, Population growth is just one of the factors causing increased emissions of CO2. Increasing wealth is another–and increasing wealth winds up correlating with decreasing fertility. What is more, as global population decreases, it raises problems for how so few young workers will support all us old farts in our dotage. Demographics may wind up being a problem that makes solving climate change look trivial by comparison.

    And no, we won’t save the planet merely by cutting consumption. What we may do is buy time–time to come up with a technological solution that saves our bacon. Time is what we have squandered. Time is what we now need most of all.

    Comment by Ray Ladbury — 1 Sep 2013 @ 1:02 PM

  151. Lichanos, Just how do you propose to keep water from flowing downhill…especially when the power may be out due to a storm?

    Comment by Ray Ladbury — 1 Sep 2013 @ 1:05 PM

  152. Mr. Roberts asks:

    “I wonder if the canyon’s got a deep opening into the Arctic Ocean.”

    From Bamber(2013)

    “For ~200 km, it provides an uninterrupted hydraulic pathway (Fig. 3 and fig.S3A) that ends at the terminus of Petermann Gletscher.”

    if that helps any.

    I probably could dig out more detail on Peterman grounding line, but you might wanna look at neven’s web sites where they probly have chapter and verse.

    NEGIS still worries me more than Peterman, I dunno why.

    sidd

    Comment by sidd — 1 Sep 2013 @ 7:57 PM

  153. Aha!
    http://crawfish22.wordpress.com/ — from about a month ago:

    “After a year in dry-dock, the CCGS Amundsen is once again steaming north to the Canadian Arctic for its annual Scientific Research Cruise….
    “… to bring on board two specialized ROV (remotely operated vehicle) drivers. They are going to deploy a massive cube of a robot through the ‘moon pool’ in the center of the ship and look for deep sea, cold water corals in the middle of Baffin Bay. … THEN we will get more serious about choosing the ice island that we will target as our field site. There are many between 5-10 sq km along the Baffin Island coast, some from the 2010 break of the Petermann Glacier, which we visited back in 2011 (see way earlier posts). There are also pieces from the 2012 Petermann Glacier break-off event, and at least one ice island produced by the Ryder Glacier – the neighbor of the Petermann Glacier in Northwestern Greenland…”

    Comment by Hank Roberts — 1 Sep 2013 @ 10:06 PM

  154. Re my comments at #71 and 133 – and subsequent replies.

    Based upon the initiatives that have been madethus far, and those you expect to be achieved in the coming years (not what you hope or wish for), what do you expect CO2 ppm to change to by, say, 2063? As a result of your estimate, where do you expect global temperatures to be relative to today – and what do you expect to have happened to sea levels by then?

    Once we have those views, we can model what coastal areas are threatened and what we expect to happen to our ability to grow food in 50 years time in different areas of the globe. We can project those views further into the future (another 50 years, 100 years, etc. ). We can then see our best guesses of the practical realities that we face – and determine the adaptation we will require.

    Comment by Dave — 2 Sep 2013 @ 3:32 AM

  155. Dave, if you are planning to “model” coastal & agricultural threats based on my guesstimate of the state of play in 2063, I’d respectfully suggest that that’s unlikely to be a productive use of your time.

    However, for what it’s worth, I’d venture a WAG (“wild-ass guess”) that atmospheric concentrations may be in the range of 500-550 ppm. Some thought went into that, but I still doubt it’s worth much as an estimate.

    (Captcha seems to believe in the future of carbon removal and sequestration, offering up “385”.)

    Comment by Kevin McKinney — 2 Sep 2013 @ 11:57 AM

  156. And meanwhile the tide gauges are still telling us that SLR is about 1.8 mm per year.2/3 is from thermal and 1/3 from ice melt.It is not reasonable to believe that ice melt can accelerate over the next couple of centuries to to a rate which can even remotely suggest a problem from SLR.If we have had any acceleration at all it is still way too little to make much difference to SLR.The sat data says about 3mm per year,but again the numbers don’t show cause for concern.The models for SLR are not reliable

    Comment by timwells — 6 Sep 2013 @ 4:46 AM

  157. timwells @156.
    You will likely find the reason tidal gauges still give SLR at 1.8mm/y is because “The values do not indicate the trend in each year, but the trend of the entire data period up to that year.” Further the period needs to be long due to the variations involved within tidal gauge measurements (as graphed down the link shows).
    Indeed, if SLR measured by tidal gauge were, as your allege, different to satellite measurements, why is it that graphs combining both sorts of data (eg here) fail to reflect such a situation? Why do they show gauge & satellite data are in accord? It is your assessment that looks to be “not reliable,” not the SLR modelling.

    Comment by MARodger — 6 Sep 2013 @ 9:26 AM

  158. Because some guy named Tim Wells on the internet forum says so. Got it.

    You understand people here read up on the scientific literature, no?

    Comment by Thomas Lee Elifritz — 6 Sep 2013 @ 10:19 AM

  159. #158–Ah!

    But for the caution to be useful, a clear (and reasonably correct) understanding of the term “scientific literature” would be necessary.

    The use of unsupported assertion as the sole criterion for ‘reasonable’ strongly suggests otherwise, in the present case…

    Comment by Kevin McKinney — 7 Sep 2013 @ 8:20 AM

  160. Calafat and Chambers. GRL, July 2013, doi:10.1002/grl.50731

    Not only is sea level rise accelerating, the acceleration is increasing, i.e. the rate of increase of sea level is not only supralinear, it is at least supra-quadratic.

    ” … since 1973, SL accelerations have been increasing at a significant rate of 0.002 mm/yr^3 until reaching its present value of 0.022 ± 0.015 mm/yr^2 for the 60 year record centered around 1982.”

    sidd

    Comment by sidd — 7 Sep 2013 @ 3:29 PM

  161. The average rate of sea level rise between 2005 and 2011, according to NOAA, was about 1.3 mm per year, well in line with long-term historic trends. Certain methods of measurement even showed no sea level rise in these seven years.

    http://ibis.grdl.noaa.gov/SAT/SeaLevelRise/document/NOAA_NESDIS_Sea_Level_Rise_Budget_Report_2012.pdf

    Now seven years is a blink of an eye, and this slow rate could well be due to background variation, but if we’re going to have a 2000 mm rise over the next century then Mother Earth better get a move on.

    Comment by rabbit — 9 Sep 2013 @ 9:06 PM

  162. Rabbit, you might want to take a look at what happened in 2012 and 2013. We’re right back on the 3+ mm a year:
    http://sealevel.colorado.edu/

    As Boening et al noted: “the 2011 La Nina: so strong the oceans fell”
    http://onlinelibrary.wiley.com/doi/10.1029/2012GL053055/abstract

    Comment by Marco — 10 Sep 2013 @ 12:32 AM

  163. In reply to rabbit, #161.

    From the University of Colorado

    Year
    2005.0132 36.141mm
    2011.0130 43.690mm

    For this period sea level rose 1.2mm a year.
    The most recent reading I can find is 2013.5377 with sea level at 61.386mm, that is now 3.0mm a year. Part of the reason for this is that there was a momentary dip in sea level during 2011 due to flooding in Australia and other parts of the world. Since 1993 the average rate has been 3.2mm a year.

    Comment by MightyDrunken — 10 Sep 2013 @ 7:18 AM

  164. The average rate of sea level rise between 2005 and 2011, according to NOAA, was about 1.3 mm per year, well in line with long-term historic trends. Certain methods of measurement even showed no sea level rise in these seven years.

    Your link doesn’t work but I don’t need it to recognize that you are regurgitating a false claim. Why don’t you start at the beginning so that I don’t have to make the obvious conclusions about your motivation.

    Comment by Thomas Lee Elifritz — 10 Sep 2013 @ 7:29 AM

  165. Thomas lee Elfritz:

    My, we are political here aren’t we? Any evidence that is not consistent with certain views is met immediately with attacks on motivation. Not exactly a scientific attitude, is it?

    Here’s the correct link. Sorry for the problems with the original. You’ll note that there is no apparent slowdown in rise in 2010-2011. And the average rise is 1.1 mm, not 1.3 mm as I originally claimed.

    http://ibis.grdl.noaa.gov/SAT/SeaLevelRise/documents/NOAA_NESDIS_Sea_Level_Rise_Budget_Report_2012.pdf

    Comment by rabbit — 10 Sep 2013 @ 8:48 AM

  166. “rabbit” picked cherries; that misstatement about that paper has been promoted a lot at denier sites, and nowhere else.

    The paper’s not about detecting the longterm trend; it’s about correlating three different sources of data that overlap for that short period of time.

    The longterm trend has short-term variations, and “rabbit” fell for people promoting short-term variation as a trend.

    ‘rabbit’ should read the science — and take Statistics 101.
    Or find sources that are trustworthy.

    Comment by Hank Roberts — 10 Sep 2013 @ 10:30 AM

  167. My, we are political here aren’t we?

    No, I am reality and evidence based and have worked with a tide guage in the past and I am familiar with the technical literature on sea level rise.

    I’m sure you find Mr. Leuliette’s condensed analysis fine for casual reading, but look at the error bars. I then actually checked Mr. Leuliette’s historical reading list to find out a little more about this gentleman.

    Gosh, Mr. Leuliette seems a bit over-enthusiastic to reconcile a wide variety of course disparate results from a bunch of different instruments. Certainly you must consider his opinion to be the final word on this, no?

    Comment by Thomas Lee Elifritz — 10 Sep 2013 @ 10:44 AM

  168. As an example, take King County (handy because it’s an image found in search but not one of the majority that are posted by the denier sites to mislead).

    An uneducated eyeball can claim to “see” a change after 2005 by just looking at this picture; so can the deniers.

    A person competent in statistics, or knowing one to trust, sees the longterm trend and the variation year to year — and knows that the more variation, the longer the data set you need to do the arithmetic, to conclude a trend is observable.

    http://www.kingcounty.gov/~/media/environment/climate/images/Impacts-mean-sea-level-trend.ashx?w=625&h=606&as=1

    If ‘rabbit’ wants to learn statistics, help is available.

    Comment by Hank Roberts — 10 Sep 2013 @ 10:53 AM

  169. rabbit is trolling. If the initial post wasn’t enough evidence, accusing those who look at the full span of evidence of being political is enough evidence.

    Comment by Ric Merritt — 10 Sep 2013 @ 11:39 AM

  170. Re short term variations:

    Repost from #82 (page 2)

    New Scientist plugging a report today that increased rainfall and flooding in Australia in 2010 involved so much water that sea level fell by 7mm.

    Link

    Comment by prokaryotes — 10 Sep 2013 @ 1:00 PM

  171. The paper from #165 above states

    above numbers represent the globally averaged changes in sea level and have magnitudes on the order of millimeters per year. The regional patterns of sea level change, however, are many times larger and can be extremely complex. Steric sea level change is the dominant contributor to the spatial trend patterns observed for total sea level (Figure 3). While the global ocean has been gaining mass from the continents during this period, the Indian Ocean continues to show a net loss of mass to the other basins (Chambers and Willis 2009).

    and the new findings (link from #170) reveal

    Satellite data showed that more water was stored on land in 2011 than in previous years, most of it in Australia, South America and South-East Asia (Geophysical Research Letters, doi.org/nhk). An early explanation was a strong La Niña, which funnelled warm, moist air towards Australia. But La Niña events happen every few years and regularly make it rain in Australia, says Fasullo. “Why don’t we see massive sea level drops after all La Niñas?”

    Triple whammy

    Re-examining weather records revealed two other factors. The Indian Ocean was much warmer in the east than in the west, pushing yet more warm, moist air towards Australia. This had not happened for 20 years. At the same time, a band of winds circling Antarctica shifted to the south, boosting the effect still further (Geophysical Research Letters, doi.org/ngx).

    The rare combination of events led to unusually heavy Australian rainfall, says Fasullo. But why did the water stay out of the oceans for so long? Extra rainfall on land should get washed back out to sea by rivers within a few months.

    It turns out that Australia has an uncanny ability to trap water for long periods. River channels are sparse in the west, so rainwater tends to sit in the sandy soil. And in the east, many of the channels run into a low-lying desert basin at the centre of the continent rather than out to sea. With heavy rains, the basin fills up to become Kati Thanda-Lake Eyre; fish eggs lying dormant in the soil hatch, and an ecosystem briefly comes to life. “It’s an instant inland sea,” says Fasullo.

    Comment by prokaryotes — 10 Sep 2013 @ 1:13 PM

  172. List of floods in Australia and on the other side of the Indian Ocean you have countries like Pakistan, India or Bangladesh, which all had exceptional floods in the past 10 years, because of changes in the natural variability, namely Monsoon and/or storm tracks and from increased evaporation rates.

    So in other words the Australian continent is a SL buffer, at least for now.

    Comment by prokaryotes — 10 Sep 2013 @ 1:32 PM

  173. rabbit wrote: “Any evidence that is not consistent with certain views is met immediately with attacks on motivation.”

    Your motivation was questioned, not attacked, which is an appropriate response to rote regurgitation of long-debunked denialist talking points that are not “consistent with” the actual evidence.

    And the fact that you immediately characterize that response as “political” gives further evidence of your motivation.

    Comment by SecularAnimist — 10 Sep 2013 @ 1:49 PM

  174. “It’s not the trolling, it’s the biting.”
    — Marion Delgado

    But, hey, there’s always the possibility someone will listen long enough to go ask a librarian, or other trustworthy source, for help checking what s/he believes.

    We all have our heads full of stuff that ain’t so. One way or another. It holds the rest of the filling together. And it’s mostly stuff we remember from fifth grade, and “it’s a poor memory that only works backward.”

    If ‘rabbit’ weren’t trolling, he/she could go find a librarian and ask for help finding facts.

    If ‘rabbit’ doesn’t have a library, that’d be too bad, tho’.
    And if ‘rabbit’ is here looking for an argument ….

    Comment by Hank Roberts — 10 Sep 2013 @ 8:47 PM

  175. @132 MA Rodger says:
    “…How she’d cope with deniers like Lichanos @128/129 …”

    Not clear on just what it is that I am accused of denying in my comments!

    There seems to be a tone here that to disagree is to be a member of the Yahoo-Denier crowd. Shouldn’t we keep to specifics?

    Comment by Lichanos — 12 Sep 2013 @ 10:25 AM

  176. > Lichanos … what am I accused of denying ….?
    In your own words:

    nobody heeds your prescient warnings! Those are fictional creations – get real.
    Comment by Lichanos — 28 Aug 2013 @ 10:08 AM

    Public Health
    Late Lessons from Early Warnings: Toward Realism …

    Yes, yes, the U.S. House of Representatives is evidence that some behave as you claim everyone behaves. But they’re not the world.

    Comment by Hank Roberts — 12 Sep 2013 @ 10:49 AM

  177. @176 Hank Roberts

    Alas! Irony and humour are to no avail…

    “You speak in the tone of Jor-El before the catastrophe, or Hari Seldon of the Foundation Series…”

    I was comparing the tone of the poster to two fictional creations, and suggesting that they were not good role models.

    Comment by Lichanos — 12 Sep 2013 @ 12:24 PM

  178. And also for Lichanos:
    http://image.slidesharecdn.com/latelessonsfromearlywarningsaboutenvironmenthealthhazards-davidgee-121114044402-phpapp01/95/slide-42-638.jpg?1352890216
    from
    http://www.slideshare.net/cccep/late-lessons-from-early-warnings-about-environment-health-hazards-what-can-we-learn

    Comment by Hank Roberts — 12 Sep 2013 @ 12:46 PM

  179. Re- Comment by Lichanos — 12 Sep 2013 @ 12:24 PM
    “I was comparing the tone of the poster…”

    Because you did not identify who you were talking to (28 Aug 2013 @ 10:08 AM) you pasted everyone with your “fictional creations” label and several folks took offense. I suggest that you take your own advice (12 Sep 2013 @ 10:25 AM) – “Shouldn’t we keep to specifics?”

    Steve

    Comment by Steve Fish — 12 Sep 2013 @ 1:16 PM

  180. @178 Hank Roberts

    Thanks you for the slide highlighting the centrality of ethics to this discussion. I agree with the slide completely. That was basically the point of my comment – I didn’t criticize the science (although I could) but raised philosophical-ethical-social concerns. I would love to have that debate.

    The problem as I see it, is that many try to use science to quash that debate. The anti-AGW people will often simply argue against the science, but ignore the precautionary principle. Or claim that it is silly. I don’t agree: it has its uses. The AGW faction tries to demonstrate categorically that we are in for some disastrous changes and claims that to ignore the evidence for that is foolish or shortsighted. The evidence is always presented as totally conclusive.

    We need to discuss how much risk we are willing to live with, and who pays? Such discussion, however, is often ruled out as denialist-babble because it entails the possibility of rejecting strong anti-carbon action (or even just some of it). Thus, the apocalypse is often invoked to structure the debate in a way that to take that position is to call down upon society certain destruction, obviously an upalatable choice.

    Not realistic, not true…

    Comment by Lichanos — 12 Sep 2013 @ 2:00 PM

  181. Lichanos @175.
    Your comments made such light of the impacts of SLR and storm surge that I took the liberty of looking down the link you provide for yourself. If you are not the author of the comment I found there – “There is no more reason to accept the conclusions of the IPCC regarding the future of the climate than there is to accept the pronouncements of the Brookings Institution (liberal) or the Cato Institute (conservative) on questions of social or economic policy.” – then my apologies. But then, you would I assume agree the quote I found is denying AGW.
    As for keeping to “specifics” – you may have an opinion on Miami or the Tower of London but I get the impressions these are locations not specific to you, even though you are here fully dismissive of their continued existence.

    Comment by MARodger — 12 Sep 2013 @ 3:30 PM

  182. > The evidence is always presented as totally conclusive

    What evidence do you have for that claim, and why do you consider your source reliable?

    That sounds like misinformation you’d have picked up from reading chatroom/blogscience sites — not here.

    > raised philosophical-ethical-social concerns.
    > I would love to have that debate.

    Look at the right sidebar on each page. There are sites where that debate you want to have is actively going on. Those are some of them that have some respect for the science.

    Avoid the chatroom/blog-science discussions.

    Look for evidence weighed not dismissed, probabilities discussed with knowledge of how they’re figured, and confidence assessed rather than asserted. That’s how it’s done.

    Comment by Hank Roberts — 12 Sep 2013 @ 7:50 PM

  183. 145 Hank R, yes, that 120ish maximum has held so far. But today’s newborns will be dealing with 2100 tech. And even if it’s just getting everyone close to 120, that’s a lot of added population.

    146 Steve Fish, I’m not sure. I did see a Ted talk where the speaker was planning on living many hundreds of years. In any case, It’s all a bunch of wild-ass speculation.

    Comment by Jim Larsen — 12 Sep 2013 @ 9:40 PM

  184. 180 Lichanos said, ” The evidence is always presented as totally conclusive.”

    When 97% of experts in a field tell you it’s totally conclusive, how dim would one have to be to take the stance that there’s ever so much to be debated…..

    Comment by Jim Larsen — 12 Sep 2013 @ 9:59 PM

  185. ps, remembering the topic here is the inevitability of sea level rise — if you have doubts about that, citing sources you consider trustworthy, and saying why, would be the way to go.

    If your complaint is with the IPCC, this isn’t likely the place to win an argument about that.

    As they say there, “Climate change is clearly a broad, complex problem requiring consideration from scientists, politicians, communities and individuals. But the language employed by the IPCC tells us that human-caused temperature increases is a well-understood theory, comparable to our understanding of gravity.”

    The climatologists have already shown themselves a whole lot better at predicting the near future than the economists have ever been able to do, and the longer term work looks even stronger as the variations average out and the trend emerges.

    Comment by Hank Roberts — 12 Sep 2013 @ 10:31 PM

  186. Lichanos,
    The entire risk debate is often associated with that type of babble, because it opens the possibility that we are willing to take that risk. Everything we do involves some risk. To deny that, denies reality. Every action we take should be anayzed for not just the risk involved in such action, but the risk of not acting. Those people living in earthquake, hurricane, tornado, and flood areas measure these risks constanly (at least should). All this relies on data that has a varying degrees of conclusivity.

    Comment by Dan H. — 13 Sep 2013 @ 6:52 AM

  187. Dan H., Most assuredly, everything we do involves risk. However, we must remember the definition of risk–probability of event multiplied by its cost should it occur. However, there are some costs that would be unacceptable even at very low probabilities–that is why Russian roul–ette has never caught on as a popular game of chance. It is also why the first step in any risk calculus is to bound the risk from above.

    The bounds on sea level rise to date do not take into account potential tipping points precisely because we don’t know how likely such tipping points are–that is we can’t bound the risk. The result is that threat avoidance is the only viable risk mitigation.

    Comment by Ray Ladbury — 13 Sep 2013 @ 8:57 AM

  188. So — look at the entire program, from which Lichianos liked one slide I linked earlier. It’s retrospective. It begins:

    “If one looks at history, there has often been sufficient science to justify precautionary actions to reduce or eliminate harm from hazardous agents, decades before effective regulatory actions ….”

    Lessons learned. Or not.

    Comment by Hank Roberts — 13 Sep 2013 @ 10:53 AM

  189. Just a question. If the sea level rose by .2 meters in the 20th century due to CO2, what cause it to rise by .2 meters in the 19th century?

    [Response: Your question doesn’t make much sense. Sea level rise is currently around 3mm/yr, up from ~1mm/yr one hundred years ago. Some of the rise is related to very long hangovers from the last ice age, but most of what is happening now is related to ice melt and ocean warming associated with human activities. Human activities are increasing and will have larger effects in the future. A change of only 20cm in the next century is highly optimistic. – gavin]

    Comment by Morgan Wright — 13 Sep 2013 @ 11:13 AM

  190. Lichanos (my bold):

    We need to discuss how much risk we are willing to live with, and who pays?

    The ethical problem in a nutshell is that the “we” who are creating the risk mostly aren’t the “we” who will pay. Anyone who says “I’m willing to live with the risk” is willing to sacrifice millions of the world’s poor, if even a moderate scenario comes to pass.

    Comment by Mal Adapted — 13 Sep 2013 @ 2:24 PM

  191. If “science to justify precaution” is the problem, well, look at human history in its dismal repetition for the say twenty thousand years or so before writing and science began.

    There have been smart innovators forever, but rarely one in any particular village during the average person’s lifetime, most just slogged on without learning much or retaining it long enough. Cultural transmission sucked before writing.

    Once those few really innovative thinkers could get the benefit of others’ work by reading it and writing more — we got science.

    Boom, industrialization, and this developmental path we’ve been on for just a few hundred years, on this planet.

    Now you can say, well, blame science — and fall back to the experience of millenia without science: oligarchy/kleptocracy.

    Or you can say, well, science — and do better.

    Inevitable consequences — as warned of hereabouts — aren’t PR, they aren’t rhetoric — they’re physics.

    Comment by Hank Roberts — 13 Sep 2013 @ 3:04 PM

  192. 180 Gavin. You said 3 mm per year now and 1 mm per year in 1913. Did you make that up? All the old data that NOAA has on seal level rise, which goes back to the 1850’s, shows a linear and non-accelerating rise of 2 mm per year. That’s 2 mm and year now, and 2mm a year in the 1850’s. We weren’t even burning coal yet. http://www.hyzercreek.com/SFsealevel.jpg

    [Response: Silly me. I thought we were talking about global sea level. I have no information on seals in San Francisco beyond what I read on the internet. Sorry. – gavin]

    Comment by Morgan Wright — 13 Sep 2013 @ 5:07 PM

  193. Hank Roberts: “Cultural transmission sucked before writing.”

    Not really. Consider the Pali Canon. In written form it is thousands of pages long. Yet it was transmitted orally for several centuries before it was ever written down, by thousands of monks who memorized and recited every single word of it. That is a skill that few, if any, modern people have.

    Comment by SecularAnimist — 13 Sep 2013 @ 5:12 PM

  194. 193 Secular, I’ve got to back up Hank on this one. Thousands of monks (who tend to be very dedicated workers) spending their lives preserving – and I’m guessing not divulging to the common man – one work. I’d say that defines sucking. Heck, I’d say cultural transmission sucked before computers.

    Comment by Jim Larsen — 13 Sep 2013 @ 7:37 PM

  195. 192 Gavin: If you need data on a location without seals, which goes back 158 years, you can try this one.

    http://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?stnid=8518750

    It’s a linear rise of 2.77 mm per year, with no acceleration from 1855 to 2013. I wonder why the sea level rise is not accelerating, in San Francisco, New York, or any of the other locations that NOAA has listed there. Can you please explain it to me? I’d like to know. Cheers. Sorry about the seals typo.

    One more thing. Please don’t mix data sets. Don’t graft satellite altimetry data onto tidal gauge data and call it acceleration. Thanks.

    Comment by Morgan Wright — 13 Sep 2013 @ 7:54 PM

  196. During the last several decades, the upward historical trends, quantified from a small set of California tide gages, have been approximately 20 cm/century, quite similar to that estimated for global mean sea level.

    http://www.werc.usgs.gov/ProjectSubWebPage.aspx?SubWebPageID=2&ProjectID=238

    Comment by Hank Roberts — 13 Sep 2013 @ 10:00 PM

  197. Morgan Wright @195.
    Wouldn’t it be just great if we could stick a tidal gauge in New York harbour and use it to monitor global sea level rise. But for reasons of a scientific nature, they don’t do that. Instead they faff about with hundreds of gauges all round the world. And they aren’t even happy with that and so they send instruments all the way up into space to measure the level of the oceans away from the coastlines.
    That’s a big job they’ve set themselves. So don’t be mean. Don’t start asking “why?” Don’t wave the results from a single tidal gauge with a straight line drawn through it as proof of an absence of accelerating SLR. Coz if you do, somebody will have to explain why your talking nonsense.
    If you wish to see the result of all the tidal gauge work all round the globe, see here. (It may take two clicks to ‘download your attachment’). The acceleration is present and is obediently following the top IPCC estimate.

    I note you say @192 of the 1850’s (sic) – “We weren’t even burning coal yet.” I’m not who you take to be “we” but some folks were, and so sneaked a bit of a head start on the rest who haven’t caught up (in per capita terms, that is). And some likely never will. These third world countries – they just haven’t got the hang of this CO2 emissions thing, have they?

    Comment by MARodger — 14 Sep 2013 @ 4:29 AM

  198. Church and White (2011) Surv Geophys (2011) 32:585–602 DOI 10.1007/s10712-011-9119-1
    freely available from

    http://link.springer.com/article/10.1007%2Fs10712-011-9119-1

    “Sea-Level Rise from the Late 19th to the Early 21st Century”

    has a good synthesis.

    sidd

    Comment by sidd — 14 Sep 2013 @ 12:38 PM

  199. Morgan Wright:

    One more thing. Please don’t mix data sets. Don’t graft satellite altimetry data onto tidal gauge data and call it acceleration. Thanks.

    What’s your argument against it?

    Comment by Mal Adapted — 14 Sep 2013 @ 3:22 PM

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