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Unforced Variations: Nov 2012

Filed under: — group @ 1 November 2012

I can’t think what people might want to talk about this month…

476 Responses to “Unforced Variations: Nov 2012”

  1. 101
    Hank Roberts says:

    And Bernie Krause has a twitter feed, and is doing book/speaking appearances right now. E.O. Wilson’s the cover blurb. Hm.


    The small signals take a lot of listening to emerge from the background.

    Hm. Bet there’s a climate change signal in there.

  2. 102
  3. 103
    Jim Larsen says:

    Here’s some very good ideas about a system to protect NYC from sea level rise. The plan calls for handling 30ft surges via recycled glass reefs, semi-submerged islands, and absorbent streets, amongst other things.

    flxible, you’re on VI? I was in Parksville. I don’t know how municipal waste was handled, other than being separated at the transfer station.

  4. 104
    wili says:

    If sea level is guaranteed to rise and we don’t know by how much nor how much higher the next super-storm will surge, isn’t it (past) time to start relocating away from the shore, particularly from the lower-lying regions?

    How many of our rapidly depleting resources should we allocate to what we know is going to be a lost cause in the coming years and decades? How much CO2 would be produced in the process of building all these reefs, islands, streets…

  5. 105
    prokaryotes says:

    Today with the election in the USA, i came up with this Idea for Climate Action:

    Assemble a letter, written by Climate Scientist, with the warning about unchecked climate change and sent it to the next President of the United States.

  6. 106
    Chris Dudley says:

    Chris (#93),

    The models have a range of equilibrium sensitivities and this might explain part of the the difference and the scaling factor might be 1.26 if I am reading this table right:

    Looks like you’ve got a factor of 1.7 or so. Not a complete explanation. RCP 2.6 should be somewhat comparable to RCP 3-pd.

  7. 107

    Post-Sandy, I’ve been wondering about micro-attributional studies.

    Presumably, you could run weather forecast model ensembles of such a storm with varied boundary conditions (SSTs, say, for a random example. ;-) ) There’d be no assurance that any altered set of conditions would necessarily be ‘realistic’ in a specific way, I suppose, but you could at least run ‘reasonable’ parameters and see what fell out.

    Have such experimental designs been tried? Or would this be of insufficient general scientific interest?

    This one looks pretty similar in outline:

    It’s from this search:

  8. 108
    Chris Korda says:

    Chris Dudley @106: Thanks for that link, however I notice the table does not include GDFL-CM3, only GDFL-CM2.0 (ECS=2.9) and GDFL-CM2.1 (ECS=3.4). I tried re-fitting the CM3 graph to my “fast” climate response graph using a range of ECS values from 3.4 to 4.0, and I get a tolerable fit at ECS=4.0. But I’m still confused! If in fact CM3 uses an ECS of 4.0, what’s the justification? And if that’s so, it appears they’re increasing their ECS with each successive generation of their model. But why would they do that?

  9. 109
    Jim Larsen says:

    Jim, some details:

    I’m abusing the word slash, and also forestry. “Woods” or even “glorified yard” more properly defines my example. Berms that block the view of a neighor’s house. Berms with preceeding ponds which catch runoff. Stuff that adds human appeal while making sense for the planet and biosphere.

    The logger cut down topped and undesireable trees, leaving a large amount of downed wood. On VI, downed wood is free. I got bookoos of firewood, left much uncut but ready, and the rest became slash.

    My CH4 concerns weren’t about rot, but insects. VI is a tenuous environment for termites, but provide a smorgasboard and things happen.

    On exponential decay of protected wood. The timeframes are surely huge. Quite a few hundreds-of-year-old houses are in grand shape. Modern preservatives are much better. So….?

    [Response:Treated and dry structural framing wood is not even remotely close to buried logs in terms of decomposition rate. I was referring to the latter. And a lot of it ends up in landfills well before its lifetime is up.–Jim]

  10. 110
    Chris Dudley says:

    Chris (#108),

    Yes CM2.1 was the parent of CM3 and was used in the last assessment.

    Now, I’m speculating completely but the RCPs are not just carbon dioxide. They’ve got other forcing in them as well. It could be that CM3 is especially sensitive to one of those?

    I’m not sure.

  11. 111
    David B. Benson says:

    Indian Monsoon Failure More Frequent With Global Warming, Research Suggests
    Food will be harder to come by, methinks.

  12. 112
    Guy Rowland says:

    New report from accountants Price Waterhouse Cooper – .

    The summary: “Even doubling our current rate of decarbonisation, would still lead to emissions consistent with 6 degrees of warming by the end of the century. To give ourselves a more than 50% chance of avoiding 2 degrees will require a six-fold improvement in our rate of decarbonisation.”

    I don’t pretend to be an expert, but that sounds pretty bad to me. Any comments?

  13. 113
    wili says:

    Guy Rowland wrote at #112: “that sounds pretty bad to me. Any comments?”

    It is bad. Beyond bad, really, if you’ve read what six degrees means in Lynas’s book of the same name.

    As I recall, that is now Hansen (NASA), Birol (IEA), Brown (WWI), and now Price Waterhouse Cooper that have all recently pointed out the likelihood of a six degree rise before the end of the century. Those are pretty major figures and main stream institutions.

    People around here don’t seem to want to talk about these catastrophic scenarios.

    Understandable, but rather disappointing for the major science-based climate forum in the world.

  14. 114
    Tom Adams says:

    I posted earlier that Romney would become the poster boy for sea level rise denial after his campaign remarks. I meant in decades, but it took only a few weeks:

  15. 115
    Pikkles says:

    With all the talk of increased extreme weather events that accompanied Sandy, I got to thinking big picture, so to speak.
    I was taught in 7th grade earth science that we are living in the coldest and most variable climate of the Cenozoic era and beyond, that is, the climate of the Late Quaternary. Global environmental variations in temperature, glaciation, aridity, ecology, etc. have not been so consistently extreme for millions of years, since the last so-called “icehouse earth” phase hundreds of millions of years ago, and these extreme changes have been more or less constantly occurring throughout the Quaternary Period; the most recent example of this being, of course, the last glacial termination, which saw sea levels rise at rates as high as 16 meters in three centuries as the huge ice sheets melted in pulses, with accompanying massive rapid shifts in global and regional climates that amounted to roughly 8 degrees celsius global warming overall; changes, in other words, that utterly dwarf those of the past 200 years in terms of rate and overall quantity of change.

    A non-7th Grade earth science corroboration of this information is the well-known 2005 Liesiecki and Raymo study of d18O in ocean sediment cores going back to the beginning of the Pliocene

    Unless I am very much mistaken, their findings demonstrate what has been fairly well-known to biogeographers and paleontologists for decades, i.e., that past warmer climates of earth in the Cenozoic saw less aridity, wider global forest cover, and generally decreased variability in global climate. Glaciations were not nearly as drastic as those of the Late Quaternary, the earth was wetter and warmer, with increased maritime influence on climate worldwide, expanded tropical rainforests, deciduous forests growing at the poles etc. etc. this is well known from the fossil record.
    In short, the Pliocene earth, which was much warmer than the earth of 2012, was not some sort of hellish inhospitable Venus, devoid of life. In fact, the exact opposite seems to have been the case.

    So, to get to my point, my question is, as the earth warms this time around due to our CO2, why are we more likely to see more aridity, more extreme climate patterns, and more climate instability, when in past warmer earths, the opposite was the case? is it not more likely that as the earth warms it will return to a similar state as that of the Pliocene, with reduced long-term climate variability and increased atmospheric moisture leading to decreased global aridity?

    Do we have any proof from studies of the past that storms were more frequent and lethal during the early Pliocene than they are now?

    Considering that the alternative to AGW is almost certainly a relatively soon and definitely economically and ecologically undesirable deterioration of our interglacial climate in the form of a gradual return to glacial conditions over the coming few dozen millenia, shouldn’t we be considering the possibility that there may be some long-term benefits from our extra CO2 contribution, such as those mentioned above?

  16. 116

    I don’t pretend to be an expert, but that sounds pretty bad to me. Any comments?

    It is bad. Add in another two billion people to the several billion all scrambling to obtain a minimum of modern fossil fuel powered conveniences and it’s really bad. Then consider a $20 trillion dollar national debt.
    If you aren’t looking directly at space and at fundamental electronic excitations you are looking in the completely wrong direction – humanity. A humanity that has an obvious predilection to the irrationality known as religion, authoritarianism and outright fascism and violence.

    Good luck with that. Humanity got you into this problem, only individuals will get you out of it. People who lead by example, not for the lust for power and money.

  17. 117
    MARodger says:

    @112 & 113.

    That PWC report presents some stark conclusions but are they really any different to the usual expression of required emission cuts – the need for emissions to have peaked by 2020?
    PWC do not actually say it is all too late. Note the PWC conclusions – as well as talking of a need to start considering plans for a global temperature rise of 4°C as the 2°C limit will not be achieved with current rates of decarbonisation, they do not say 2°C is a totally impossible target, only that such a target “…suggests a need for much more ambition and urgency on climate policy, at both the national and international level.

    Apart from being more complex, their analysis of required carbon intensity reductions both for the world economy and individual nations is perhaps an improvement on the usual straight carbon emissions & the report’s annual nature is very good (although as they note, they are still hooked on to ‘production’ emissions not ‘consumption’ emissions.)
    This year the PWC analysis yields a required continual annual reduction in global carbon intensity of 5.1%, up from 4.8% last year. This is not good news but perhaps their Figure 1 should give us some encouragement. The reductions achieved between 2004 & 2007 at least paralleled their suggested decarbonisation course. So when more folk come on board to address emission cuts, when denialists are at last treated as pariahs, then that graph can surely be steepened and brought back on course.

  18. 118
    Dan H. says:

    You are correct about the climate during the Pliocene, and any temperature increase would likely mimic that era. The increased moisture is supported by most studies of rising temperature. The contentious claim is climate variability, especially if unequal polar warming leads to lower gloabl temperature gradients.

  19. 119
    Susan Anderson says:

    What’s interesting is PriceWaterhouseCoopers. PWC is not your run of the mill climate change alarmist.

    Pikkles, there are many fine scientists here, but neither I nor Dan H are among them. The latter’s intentions, however, have been demonstrated to be devious, so you might want to look past his remarks.

  20. 120
    Pikkles says:

    Devious Dan,

    the above site gives a somewhat dated brief overview with references of the current understanding of Pliocene climate (as it was a decade ago, at least)

    note that according to the author, “The best that one can hope for in terms of summarizing Pliocene climates is to talk of them in a statistical sense; in terms of averages, mean variance, period of oscillation etc. as they appear in the record. These statistical characteristics themselves shift throughout the period of the last few million years going into the Quaternary Period, with a decline in mean temperature and a trend towards increased aridity, and broader oscillations in both temperature and aridity.”

    this relatively much more moderate (as compared to Quaternary) global milankovitch-induced climate oscillation in the Pliocene is also supported by the Liesiecki Raymo 2005 study linked above. The d18O graph on page 6 of that study is particularly demonstrative.

    As for the question of climate variability and extremes on the hundred-year scale within those larger oscillations, I have yet to find a study that addresses it. If you know of any I would greatly appreciate any help. For all I know that level of fine century-level detail from ~4 million years ago is beyond the capacities of current science.
    Also any studies concerning the strength and severity of storms during the Pliocene or Miocene would be helpful.
    Models and predictions for increasingly extreme and freakish weather are all well and good, but I think you would agree that a firm understanding of an analogous past warmer climate such as the Pliocene would clear up a lot of the vagueness of the current, often dire predictions.

    Non-devious Susan,
    I do not see that Dan H. has been devious in his response to my above post. Perhaps he is more wayward elsewhere…
    This quote from the Oak Ridge site linked above agrees with what he wrote and what I wrote in re warmer, wetter climates of the recent Cenozoic past:
    “Whether or not there was a close relationship between temperature and aridity during Pliocene, the general band of variability seen in the long cores suggests that even the most arid oscillations of the Pliocene were probably nowhere near as arid as the Last Glacial Maximum, and during the generally warmer parts of the Pliocene even the dry minima of individual oscillations may actually have been wetter than at present.”

  21. 121
    Hank Roberts says:

    > a much better network of flux towers measuring atmostpheric C flux directly,

    Well heck, people are putting webcams and Geiger counters on the Internet; how hard is it to build a CO2 sensor, calibrate it, and get it an IP address? Kickstarter?

    [Response:Not just any old CO2 sensor Hank, it has to be able to measure CO2 flux across the air-vegetation interface (using eddy covariance techniques). And since CO2 flux depends on micro-meteorology, you have to measure temp, wind, humidity as well. And in forests you also have to build a tower, potentially a very tall, multi-level one, to position the sensor in the right location relative to the canopy. And you have to wire it all up to data loggers. And it only takes one falling tree, or part thereof, to wreck the entire apparatus.–Jim]

  22. 122
    Hank Roberts says:

    > any temperature increase would likely mimic that era.

    Bzzt. You’re neglecting the rate of change again.

    If we could get the rate of change down to that Pliocene rate we’d barely notice it in a human lifetime and adaptation would happen naturally.

    That’s the whole problem with anthropogenic fossil fuel use — rate of change.

    D’oh. Chased another dang red herring.

  23. 123
    Troy_CA says:

    Chris Korda (#108):

    “I tried re-fitting the CM3 graph to my “fast” climate response graph using a range of ECS values from 3.4 to 4.0, and I get a tolerable fit at ECS=4.0. But I’m still confused! If in fact CM3 uses an ECS of 4.0, what’s the justification? And if that’s so, it appears they’re increasing their ECS with each successive generation of their model. But why would they do that?”

    See Winton et al. 2012:, where it appears the ECS for GFDL CM3 is actually 4.6K. The ECS is an emergent property and not explicitly specified, but here is the author’s speculation as to why it is so much higher than previous versions:

    “The cause of the increased ECS in CM3 is unknown, but is presumably related to differences in moist physics (including convection and aerosol-cloud interactions) between AM2 and AM3”.

  24. 124
    Hank Roberts says:

    > Pliocene … a decade ago

    Scholar finds over 3000 hits for 2012:,5

  25. 125
    Hank Roberts says:

    And even a mere repeat of that paleo rate of change wouldn’t be calm and uneventful:
    Abrupt landscape change post–6 Ma on the central Great Plains, USA
    How much faster is the rate of change at present?

  26. 126
    Mike Roddy says:

    Here is an excellent summary of forestry carbon myths:

    It is based on peer reviewed literature, and the data has not been seriously challenged. I used a couple of the slides for my article, linked above, called “The Real Score on Logging and CO2 Emissions”.

    If anyone would like to ask questions, I can be reached at

    The forester above didn’t consider the end use, and whether the carbon remains sequestered for long periods. I second Jim Bouldin’s comments here. The problem of escaping into the atmosphere is especially serious when compared with alternate materials. I calculated that the emissions burden of steel framing is a fraction of that of two by four generated emissions. It’s a complex subject, but the conclusions of my article have not been refuted.

    Thanks for this thread, Gavin and Jim. Please, RC, do a few dedicated posts on this subject.

  27. 127
    Pikkles says:

    the paper you link to above, “Abrupt landscape change post–6 Ma on the central Great Plains, USA” is primarily a geological, not climatological paper. The “sudden” changes discussed are sudden on geological timescales and would have been calm and uneventful on the timescale of a human life.
    Note the line from the abstract: “A significant episode of aggradation from 3.7 to 2.5 Ma is best explained by high rates of sediment supply relating to the warm, wet mid-Pliocene climate optimum.”

    Analogous erosive geological processes due to rainfall are going on worldwide in areas of humid climate as we speak, and have been going on throughout the history of earth.
    Rainfall increases erosion but has the benefit of supporting fully-developed vegetation and higher biodiversity, higher biomass ecosystems than arid and perenially frozen areas, as can plainly be seen on the map below:

    the area of the present great plains was likely less arid than present during the Pliocene.
    nonetheless, it appears, according the paper below, that the great plains had already become arid enough to be deforested by the beginning of the Pliocene, presumably as a result of global cooling and spreading aridification over the course of the miocene.

    as you can tell from reading the above 2011 paper’s abstract, aside from evidence of broad trends, we still have a very crude understanding of environmental conditions at the time.

    “Phytoliths were extracted from late Miocene–Pliocene paleosols in Nebraska and Kansas. Quantitative phytolith analysis of the 14 best-preserved assemblages indicates that habitats varied substantially in openness during the middle to late Miocene but became more uniformly open, corresponding to relatively open grassland or savanna, during the late Miocene and early Pliocene.”

    Not too much has changed in the past decade in that regard.

  28. 128
    SecularAnimist says:

    Thomas Lee Elifritz wrote: “Add in another two billion people to the several billion all scrambling to obtain a minimum of modern fossil fuel powered conveniences and it’s really bad.”

    There is no necessity for “modern conveniences” to be powered by fossil fuels. In fact I can think of few “modern conveniences” that are powered by fossil fuels. Most are powered by electricity, which can of course be easily generated from non-fossil fuel energy sources, which are abundant in the developing world.

    The only widely used “modern conveniences” powered directly by fossil fuels are vehicle engines, and those vehicles can also be powered by electricity.

  29. 129
    SecularAnimist says:


    USGS researchers quantify potential greenhouse gas releases from melting Arctic permafrost
    Staggering amounts of nitrogen and carbon could lead to runaway warming in coming decades
    By Bob Berwyn
    November 4, 2012
    Summit County Citizens Voice


    Scientists with the U.S. Geological Survey say they’ve quantified the amount of greenhouse gases that could be released into the atmosphere as Arctic permafrost starts to melt.

    “This study quantifies the impact on Earth’s two most important chemical cycles, carbon and nitrogen, from thawing of permafrost under future climate warming scenarios,” said USGS Director Marcia McNutt. “While the permafrost of the polar latitudes may seem distant and disconnected from the daily activities of most of us, its potential to alter the planet’s habitability when destabilized is very real.”

    As much as 44 billion tons of nitrogen and 850 billion tons of carbon could be released into the environment as the region begins to thaw over the next century. This nitrogen and carbon are likely to impact ecosystems, the atmosphere, and water resources including rivers and lakes. For context, this is roughly the amount of carbon stored in the atmosphere today.

  30. 130
    Pikkles says:

    here’s an interesting 2012 paper on modeling the warmest period of the Pliocene.

    note the following, which agrees fully with what I have written above and the sources i have cited.

    “On land, the global extent of arid deserts decreased, and forests replaced tundra in the Northern Hemisphere (e.g. Salzmann et al., 2008). On the basis of climate model outputs, the global annual mean temperature may have increased by more than 3 C (e.g. Haywood and Valdes, 2004)”

    yet again, this supports the long-held view in paleontology and paleobiogeography that warmer climates of the Cenozoic, Mesozoic, and previous supported globally widespread forests and little to no aridity.

    nonetheless, the above paper does not refer at any point to freak destructive weather. precipitation would increase in a warmer, wetter world. presumably this would correspond to more rainstorms worldwide, and accompanying decrease in aridity.
    whether these storms would be more destructive than those of the late quaternary is not quite clear.
    a non-model-based study exploring historical intensity and frequency storminess in the Pliocene would be interesting to see, but almost all of the recent studies of Pliocene climates seem to be model-based.

    If you ask me, the trade-off of global reduction of aridity for possible increased large storms is pretty even.
    It especially seems preferable to a return to glacial conditions which is likely to occur any millenium now, as we approach the end of the holocene interglacial, the brief moment of warmth in which our entire history of civilization is contained.
    I don’t see why there is not more discussion of the possible long-term benefits of global warming.
    I am not invested in or working for any petrochemical or coal companies or anything like that.
    I am merely wondering what is the best, most rational course for humanity and life on earth.
    To say that we and other life forms must condemn ourselves to the brutal glaciations of the late Quaternary simply because it is “natural”, i.e. the state we found the place in when we came to scientific consciousness, seems to border on hyper-conservative religiosity.
    the earth with modern mammals, angiosperms, grasses, etc. has been much warmer before than we will likely ever be able to make it.
    and it doesn’t seem like those warmer worlds were less habitable than that of today.
    what if it turns out that the benefits of a warmer world balance out or even outweigh the detriments?

  31. 131
    Hank Roberts says:

    Jim, how long do you need a CO2 tower operating to assess a site — a year or more?

    [Response:There’s no fixed value; as long as possible to capture the range of variability, sort of the standard answer to these type of things.–Jim]

  32. 132
    Ambulator says:


    We are told that the rapid climate change we are undergoing is heating the land faster than the ocean. If the ocean is colder than land I expect more of the rainfall to go there, leaving dry areas on land. I am uncertain how important this is.

    In any case, change is not our friend. Even if the warming is not a catastrophe I doubt it will be pleasant. How much we should do to stop it does depend on the cost, which is why mitigation strategies matter. Of course, they are off topic here.

  33. 133
    pikkles says:

    Hank Roberts
    Your linked Pliocene study in your rebutting post 125, “Abrupt landscape change post–6 Ma on the central Great Plains, USA” is a geological, not climatological study. The abrupt changes that are the focus of the paper have nothing to do with increased or decreased severe weather in the Pliocene, but rather with geological uplift, with a side mention of what seems to have been a normal aggradation episode caused by increased rainfall on the Great Plains during mid-Pliocene warmth.

  34. 134
    pikkles says:


    I suppose that would answer one of my main questions about predictions of spreading aridity due to global warming.
    Presumably after a few centuries or so, ocean temperatures would catch up to the more rapidly heated land surfaces, bringing more moisture into the atmosphere and causing global conditions more similar to those of the Pliocene (or perhaps Miocene or even Eocene if the wildest predictions of warming come to pass), in which global aridity is reduced and forest area increases.

    Still what I find problematic on face value for the immediate future is the prediction that aridity will increase while at the same time storminess will also increase.
    How can we have them both at the same time? Presumably if ocean surface temperatures remain relatively cold while continental crusts warm up, then we will have increased aridity without a significant increase in storminess. On the other hand, if surface temps warm enough to increase storminess and increase moisture in the atmosphere, it seems we would have decreased global aridity, such as during the Neolithic Subpluvial when the Sahara was vegetated due to warmer equatorial waters and strengthened African Monsoon…
    You say “change is not our friend”, but keep in mind that human civilization was unable to come into existence without the rapid global warming at the last glacial termination. as the earth warmed, aridity and glaciation decreased drastically and forest cover increased drastically.
    with some growing pains, the same general pattern will probably emerge if the earth is warmed back to Pliocene levels.
    The pains involved in the change itself seem to be the major issue. it seems unreasonable to suggest that Pliocene conditions would be unusually hostile to life, if we ever arrive at that point. Most genera of life forms on earth today were already in existence during the Pliocene particularly tree species.

  35. 135
    wili says:

    MAR at 217 wrote “PWC do not actually say it is all too late”

    Did anyone claim that they did?

    Can we please try not to misquote each other on this forum?

    And of course the phrase “too late” means nothing by itself. Too late for what?

    I agree with Susan that PWC is an interesting group to start weighing in on future global temperatures.

    I wonder if they could sway some folks on Wall Street (and its Journal).

  36. 136
    Hank Roberts says:

    > Pliocene
    Rate of change. Compare then to now.

    I gave one example from one search for only 2012 papers to point out there’s much more, and more recent, to consider, and suggest where rates of change make a big difference.

    Changes in erosion affect uplift rates, same as changes of glacial weight.

  37. 137
    David B. Benson says:

    Pikkles @115 — First of all almost all the ice has to melt to return to a Pliocene climate state. I opine that will be rather stormy. Second, the increased precipitation will be especially noticeable in the tropics. We’ve already seen the beginning effects in Asia during the last (long) La Nina. I doubt that tropical cyclones will somehow fade away; consider the source of energy.

  38. 138
    Chris Korda says:

    Troy CA @123: Thank you very much for the link. I tried re-fitting with ECS = 4.6 and got what seem to be reasonable results. The fast response shows a pretty good fit for all RCPs except 2.6 (see note below). The intermediate response fits the historical data better, but shows some divergence on the projections: RCP6 fits nicely, but 8.6 and 4.5 undershoot CM3. Fast response has been consistently giving the best fit for projections, even though it’s less accurate for historical temperatures.

    For those who may have missed the earlier chapters, this exercise began when I learned that the IEO2011 Reference case projects “1 trillion metric tons of additional cumulative energy-related carbon dioxide emissions between 2009 and 2035”. This was demonstrated to be equivalent to following RCP8.5 until 2035. Regarding this, Jon Kirwan said (Oct. open thread, #269):

    I don’t like the fact that the pre-release paper about ICPP RCPs happens to show RCP8.5 as the worst case emission scenario in that chart and that this scenario also happens to be the apparent reality in the International Energy Outlook from 2011. If the IPCC RCPs don’t include anything worse and if we are, in reality, on track for this worst case, then the other RCPs are wishful proposals more than anything else. That’s very bad. But that seems to be reality, too. I think I will use RCP8.5 as the ONLY scenario I use for thinking purposes until AFTER I see serious political action AND YEARS AFTER I see significant implementation already taking place. Until then, RCP8.5 is reality.

    I became increasingly curious about three questions: 1) Assuming we emit an additional teraton of CO2 by 2035, what average global surface temperature will likely result? 2) Why do the AR5 scenarios omit temperature data (unlike the AR4 scenarios), despite this being what most people presumably want to know? 3) Could there be inherent differences between IPCC and IEA that explain why IPCC scenarios other than the worst case are “wishful proposals”?

    In an effort to answer the first question, I attempted to model RCP temperatures, using Climate Response Functions proposed by Hansen et al. as explained here. More recently the discovery of NOAA/GDFL’s CM3 RCP temperature data provided an opportunity to compare my results to a fully-coupled model. Hansen et al. argue that “intermediate” is the most likely case and consider “fast” the upper bound, however CM3 appears to fit “fast” response, with a significantly higher ECS (4.6 instead of 3.0). If “RCP8.5 is reality” and CM3 is to be believed, we could face an increase in average global surface temperature of ~1.5ºC between now and 2035. This is an astonishing and profoundly disturbing result. And of course thanks to hysteresis the temperature doesn’t stop there, even optimistically assuming breakneck decarbonization after 2035.

    Re RCP2.6: I’m assuming it’s outdated and not equivalent to RCP3.5, and consequently I’m disregarding it for these comparisons. My indirect evidence: The official AR5 RCP data was finalized in 2009 and does not include or even mention RCP2.6. The IIASA RCP database describes RCP2.6 as having been finalized in 2007, and provides a download link for it, but the link is “broken” in the sense that it points to RCP3.5PD data, with no explanation.

  39. 139
    MARodger says:

    wili @135
    The title of the PWC report is of course “Too Late For Two Degrees?” and much of its language is quite dramatic, its opening line being “It’s time to plan for a warmer world.” I don’t see that I misquoted/misrepresented anything.

  40. 140
    wili says:

    Ah, thanks MAR. Sorry about that.

    Of course, lots of prominent people and organizations are now saying that it is, in fact “Too Late For Two Degrees”–not that this was ever some kind of safe threshold, anyway.

  41. 141
    Hank Roberts says:

    All I know about this is what I can look up. Maybe someone who’s done work in the subject will commen. Seems to me that the Pliocene is interesting as a warmer climage, but the Pliocene changed at a geological pace. By definition, slower than change at a glacial pace, much slower than change from fossil fuel.

    What sort of erosion will start to happen at the rate we’re changing the climate?
    Again, rate of change is what matters.
    If we don’t know what’s the worst that could happen, we can at least look at the worst that has happened — using Leopold’s land ethic to evaluate it.
    Late Cenozoic increase in accumulation rates of terrestrial sediment: How might climate change have affected erosion rates?
    P Molnar – Annu. Rev. Earth Planet. Sci., 2004 –
    (cited by about 135 later papers) for some more recent work

    But this did turn up an irony:
    I’d remembered but never looked up this quote from climate scientist Ray Pierrehumbert (pdf):

    So far, we’re not doing any better than cyanobacteria.

    Today I read about a suggested method of erosion control — air dropping photosynthetic bacteria. An interesting response to unnatural rate of change?

    Seeding of Large Areas with Biological Soil Crust Starter Culture Formulations: Using an Aircraft Disbursable Granulate to Increase Stability, Fertility and CO2 Sequestration on a Landscape Scale

    No wonder we’re not doing as well as the cyanobacteria.
    They’re using us to spread themselves.

  42. 142
    wili says:

    To SA at # 129. Thanks for the link to that important, if deeply troubling, article.

    You do recall that when I posted similarly dire information, you responded with:

    “‘What I don’t see much value in, is “discussion of the science” by laymen like many of the commenters here (including me), that simply leads people to retreat into despair and hopelessness and a sense that “it’s too late” to do anything.'”

    Does your posting of this despair-provoking article indicate a change in your philosophy on these matters?

  43. 143
    Hank Roberts says:

    Wili, the post above ends:

    “For context, this is roughly the amount of carbon stored in the atmosphere today.”

    You know much of the fossil carbon burned has been cycled biogeochemically.

    The article refers to doubling what’s in the atmosphere today.
    That’s “2XCO2” — not cause for despair; rather a reason to fix the damn problem.

    Despair is the counsel of the trolls and the delayers, they’d love you to despair.

    Don’t mourn, organize.

  44. 144
    Phil L says:

    Interesting discussion of forest management and carbon sequestration. In reply to Steve Fish with inline comment by Jim (# 99), and Mike Roddy (# 126), the IPCC Working Group III on Mitigation states, “Wood products derived from sustainably managed forests address the issue of saturation of forest carbon stocks. The annual harvest can be set equal to or below the annual forest increment, thus allowing forest carbon stocks to be maintained or to increase while providing an annual carbon flow to meet society’s needs of fibre, timber and energy. The duration of carbon storage in wood products ranges from days (biofuels) to centuries (e.g., houses and furniture). Large accumulations of wood products have occurred in landfills (Micales and Skog, 1997). When used to displace fossil fuels, woodfuels can provide sustained carbon benefits, and constitute a large mitigation option …Wood products can displace more fossil-fuel intensive construction materials such as concrete, steel, aluminium, and plastics, which can result in significant emission reductions (Petersen and Solberg, 2002). Research from Sweden and Finland suggests that constructing apartment buildings with wooden frames instead of concrete frames reduces lifecycle net carbon emissions by 110 to 470 kg CO2 per square metre of floor area (Gustavsson and Sathre, 2006). The mitigation benefit is greater if wood is first used to replace concrete building material and then after disposal, as biofuel.”

  45. 145
    pikkles says:

    would anybody like to comment on the logarithmic nature of CO2 climate forcing?
    i’ve read in IPCC materials and elsewhere that the opacity of the wavelengths of outgoing infrared that CO2 blocks is almost at its fullest.
    Since additional CO2 will only continue to block the same wavelengths, and since those wavelengths are already almost fully blocked, additional CO2 will not contribute significantly more forcing even if we quadruple current levels, or such is my understanding.
    in other words, since the forcing is logarithmic, the forcing increase from, for example, the jump in CO2 at the beginning of the last glacial termination, and the increase from the jump in CO2 at the start of the industrial revolution would have been much more significant per part per million than, for example, the increase from 1990 to 2010.

    if this is indeed true, then higher-than-present CO2 levels in past climates would have had a logarithmic limit, which would explain why high CO2 atmospheres of the Cenozoic and earlier did not turn the earth into an uninhabitable Venus.

    Please critique. I’m not trying to be denialistic about this. I have read it in IPCC reports. Just looking for clarification.

    [Response: You are confusing two separate things. Yes, some absorbing bands for CO2 are nearly saturated (but many aren’t). And yes, forcing from CO2 increases logarithmically in concentration. Thus going from 280 to 560ppm gives the same forcing roughly as 560ppm to 1120 ppm (indeed, this is why scientists always talk about the forcing from 2xCO2, not the forcing per ppm). But this does not mean that the impact from doubling CO2 is small, nor does it imply Venusian conditions can’t exist (since they obviously do – and CO2 is logarithmic on Venus as well). – gavin]

  46. 146
    Dan H. says:


    Here is an absorption graph of the atmospheric gases:

    You question is valid. At some point absorption will become saturated (reach its fullest) at certain wavelengths. Absorption will continue further at the tail ends until it is saturated (if possible). This is not based on CO2 alone, but on the combination of all components together – i.e. water vapor.

    At sea level, many of the IR bands are saturated (or nearly saturated). However, at higher levels in the atmosphere this is not so. Water vapor will not rise to these heights (it will freeze), so the major component becomes CO2. The expected temperature rise is expected to be largest in the upper troposphere, where increased CO2 can affect IR absorption more readily. Hope this helps.

  47. 147

    #145–“Since additional CO2 will only continue to block the same wavelengths, and since those wavelengths are already almost fully blocked, additional CO2 will not contribute significantly more forcing even if we quadruple current levels, or such is my understanding.”

    Pikkles, that was a (much over-simplified) idea that held some sway for a time during the first decades of the twentieth century. But the atmosphere does not act like a uniform ‘slab’; heat is transferred by convection and phase change as well, and radiation and emission and absorption occur at all altitudes. Moreover, there is, as Gavin’s comment implies, marked frequency dependence in radiative transfers. All in all, the problem of calculating all of this is anything but simple; solving it to the point of being able to achieve reasonable agreement with observation took roughly a century (reckoning from Arrhenius (1896), though maybe we should start with Samuel Langley (1881), whose data Arrhenius used.)

    For more on the history of the science, and the conceptual basis, try this:

  48. 148

    And from Weart, a bit down from the point where the above link goes:

    What if water vapor did entirely block any radiation that could have been absorbed by adding CO2 in the lower layers of the atmosphere? It was still possible for CO2 to make a difference in the thin, cold upper layers. Lewis D. Kaplan ground through some extensive numerical computations. In 1952, he showed that in the upper atmosphere the saturation of CO2 lines should be weak. Thus adding more of the gas would certainly change the overall balance and temperature structure of the atmosphere.

    Neither Kaplan nor anyone else at that time was thinking clearly enough about the greenhouse effect to point out that it will operate regardless of the details of the absorption. The trick, again, was to follow how the radiation passed up layer by layer. Consider a layer of the atmosphere so high and thin that heat radiation from lower down would slip through. Add more gas, and the layer would absorb some of the rays. Therefore the place from which heat energy finally left the Earth would shift to a higher layer. That would be a colder layer, unable to radiate heat so efficiently. The imbalance would cause all the lower levels to get warmer, until the high levels became hot enough to radiate as much energy back out as the planet received. Adding carbon dioxide will make for a stronger greenhouse effect regardless of saturation in the lower atmosphere.

    (And actually, there is no saturation. The primitive infrared techniques of the laboratory measurements made at the turn of the century had given a misleading result. Studies from the 1940s on have shown that there is not nearly enough CO2 in the atmosphere to block most of the infrared radiation in the bands of the spectrum where the gas absorbs it. Nor does water vapor bring complete saturation, in desert regions where the air is extremely dry.)

  49. 149
    pikkles says:

    Gavin and Dan- thanks for the clarifying information.

    This may be splitting a hair, but in the interest of accuracy, your assertion that “First of all almost all the ice has to melt to return to a Pliocene climate state.” seems problematic. here are a few studies off hand that indicate there was substantial glaciation in Antarctica during the Pliocene:

    The Greenland ice sheet is also thought to have first come into existence midway through the Pliocene.
    Of course, the ice sheets that did exist in the Pliocene would have been much smaller than those of the present day, and sea levels were correspondingly higher.
    But if, hypothetically, the earth returns to a stable Pliocene state due to our CO2, there may still be significant polar glaciation. If we return to Miocene levels of global warmth, not so much…

    As an interesting tangent, before the onset of glaciation in the Pliocene, Antarctica was once home to a unique polar forested ecosystem, the scattered botanical remnants of which have migrated north to make up the so-called “Antarctic flora” of Chile, New Zealand, Tasmania, and various South Pacific islands.

    Although it may sound somewhat macabre, the melting of the Antarctic ice sheet would eventually reveal fascinating traces, fossilized in the continental crust beneath, of ancient life barely known to paleontology, but which certainly must have existed during the Eocene, Oligocene, Miocene and other warmer past epochs.

  50. 150
    Chris Dudley says:

    Chris (#138),

    I’d just comment that RCPs are meant as inputs for climate models so that temperature can be calculated as an output. We are taking a shortcut that might give us a clue about what the GISS model might produce. It is very interesting that the CM3 model has evolved so much that its sensitivity is 35% higher than CM2.1. The GISS E model was a simplification to allow more model runs with the given computer resources. I don’t know if it will evolve as much. Gavin should know something about that.

    Maybe RCP 2.6 was dropped because of negative emissions starting around 2070? That does not seem technologically unrealistic to me, but reticence is always hiding in the cupboards and under the carpet.