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The inevitability of sea level rise

Filed under: — stefan @ 15 August 2013

Guest post by Anders Levermann [via The Conversation]

The Conversation
Small numbers can imply big things. Global sea level rose by a little less than 0.2 metres during the 20th century – mainly in response to the 0.8 °C of warming humans have caused through greenhouse gas emissions. That might not look like something to worry about. But there is no doubt that for the next century, sea level will continue to rise substantially. The multi-billion-dollar question is: by how much?

The upper limit of two metres that is currently available in the scientific literature would be extremely difficult and costly to adapt to for many coastal regions. But the sea level will not stop rising at the end of the 21st century. Historical climate records show that sea levels have been higher whenever Earth’s climate was warmer – and not by a couple of centimetres, but by several metres. This inevitability is due to the inertia in the ocean and ice masses on the planet. There are two major reasons for the perpetual response of sea level to human perturbations.

One is due to the long lifetime and warming effect of carbon dioxide in the atmosphere. Once emitted carbon dioxide causes warming in the atmosphere over many centuries which can only be reduced significantly by actively taking the greenhouse gas out again. This is because both the amount of heat and carbon dioxide the ocean can absorb is reduced, and so the temperature stays up for centuries or even millennia. Of course, not cutting emissions would exacerbate the problem even further.

The other reason is that both the ocean and the ice masses are very big and a warming of the surrounding atmosphere will only penetrate slowly, but inevitably, into them. As a consequence their sea level contribution continues even if the warming does not increase. Sea level rise over the last century has been dominated by ocean warming and loss of glaciers. Our recent study indicates that the future sea level rise will be dominated by ice loss from the two major ice sheets on Greenland and Antarctica – slumbering giants that we’re about to wake.

levermann2013

Graph: Sea level rise contributions over 2000 years from: ocean warming (a), mountain glaciers (b), Greenland (c) and Antarctic (d) ice sheets. The total sea level commitment (e) is about 2.3m per degree of warming above pre-industrial.

It is easier to understand a future world that has adjusted to a new equilibrium of higher temperatures than it is to understand the dynamic (perhaps rapid) transition from today’s world to a warmer one. That is why we used physical models for the ocean, the mountain glaciers and the big ice sheets to compute how the systems would be different if the world was warmer.

What we found was that for each degree of global warming above pre-industrial levels the ocean warming will contribute about 0.4 metres to global mean sea-level rise while Antarctica will contribute about 1.2 metres. The mountain glaciers have a limited amount of water stored and thus their contribution levels off with higher temperatures. This is over-compensated for by the ice loss from Greenland, so that in total sea level rises quasi-linearly by about 2.3 metres for each degree of global warming (see figure).

How fast this will come about, we do not know. All we can say is that it will take no longer than 2,000 years. Thus the 2.3 metres per degree of warming are not for this century. They need to be considered as our sea level commitment – the sea level rise that cannot be avoided after we have elevated global temperatures to a certain level.

Ben Strauss of Climate Central has considered the different possible future pathways that society might take and computed which US cities are at risk in the long-term. He poses the question as to what year, if we continue with greenhouse emissions at current rates, we will have caused an inevitable sea level rise that puts certain cities at risk.

According to his analysis, within the next few years Miami in Florida will be committed to eventually lie below sea level, while our future actions can still decide on whether we want to one day give up cities such as Virginia Beach, Sacramento, Boston, Jacksonville or New York City.

This is a decision society has to take for future generations. We will need to adapt to climate change in any case, but some things we will not be able to adapt to. Society needs to decide whether we want to give up, for example, the Tower of London, or to put the breaks on climate change so that we don’t have to.

Weblink: The New York Times has a good current article on this issue.

Anders Levermann is department head at the Potsdam Institute for Climate Impact Research, Germany


198 Responses to “The inevitability of sea level rise”

  1. 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.

  2. 52
    patrick says:

    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.

  3. 53
    owl905 says:

    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?

  4. 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.

  5. 55
    Hank Roberts says:

    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.

  6. 56
    Hank Roberts says:

    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….”

  7. 57
    David Miller says:

    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.

  8. 58
    Alastair McDonald says:

    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.

  9. 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.

  10. 60
    bjchip says:

    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?

  11. 61
    bjchip says:

    “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.

  12. 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.

  13. 63
    Jim Larsen says:

    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.

  14. 64
    Hank Roberts says:

    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

  15. 65
    Hank Roberts says:

    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

  16. 66
    Hank Roberts says:

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

    Would these be those?

  17. 67
    Hank Roberts says:

    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)

  18. 68
  19. 69
    mdenison says:

    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.

  20. 70
    Lennart van der Linde says:

    mdenison #70,

    Ok, in that broad sense I can follow you.

  21. 71
    Dave says:

    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.

  22. 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?

  23. 73
    Ray Ladbury says:

    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?

  24. 74
    Hank Roberts says:

    > 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”

  25. 75
    Douglas McClean says:

    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.

  26. 76
    MARodger says:

    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?

  27. 77
    Radge Havers says:

    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

  28. 78
    Ric Merritt says:

    #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.

  29. 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

  30. 80
    Mal Adapted says:

    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?

  31. 81
    flxible says:

    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.

  32. 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?

  33. 83
    Hank Roberts says:

    But wait.

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

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

  34. 84
    DHouck says:

    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.

  35. 85
    Hank Roberts says:

    > 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.

  36. 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.

  37. 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.

  38. 88
    Hank Roberts says:

    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?

  39. 89
    Ken Carr says:

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

  40. 90
    JimD says:

    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.

  41. 91
    flxible says:

    @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.

  42. 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.)

  43. 93
    Alan Millar says:

    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

  44. 94
    Killian says:

    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.

  45. 95
    Dhouck says:

    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.

  46. 96
    MA Rodger says:

    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.

  47. 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?

  48. 98
    Susan Anderson says:

    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.

  49. 99
    Hank Roberts says:

    > 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.

  50. 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.


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