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Unforced variations: May 2014

Filed under: — group @ 2 May 2014

This month’s open thread. In order to give everyone a break, no discussion of mitigation options this month – that has been done to death in previous threads. Anything related to climate science is totally fine: Carbon dioxide levels maybe, or TED talks perhaps…

394 Responses to “Unforced variations: May 2014”

  1. 101
  2. 102
    Hank Roberts says:

    Worth knowing about for tracking down the origin of “stuff” you find on the Internet:
    A blog about plagiarism and scientific misconduct

  3. 103
    Pete Dunkelberg says:

    Wally @ 99: I posted on that new Ding, Eric Steig, et al. paper in the other thread
    by mistake and got an interesting reply, although not yet from Eric.

  4. 104
    Pete Dunkelberg says:

    Antarctic ice: if we keep the heat on there is also trouble in the east:

    Ice plug prevents irreversible discharge from East Antarctica

    btw Chris, is your link one character short?

  5. 105
  6. 106
  7. 107
    The Raven says:

    There is also coverage at the Guardian, and it is not paywalled.

  8. 108
  9. 109

    #101 et seq– Hopefully, we’ll hear directly from Eric on this one.

  10. 110
    Pete Best says:

    Re #101 – going to take 1000 years for it to disappear though and hence the real issue is going to be about seal level rise the rate of contribution this century and beyond. If it accelerates along with Greenland then by the end of the century it could be much higher than the 59 cm (due to a lack of ice dynamics modelling capability apparently). As much as James Hansen once suggested – 6 ft (2 metres)due to it being a wet process as he describes it.

    Interesting the guardian article states:

    The loss of the entire western Antarctica ice sheet could eventually cause up to 4 metres (13ft) of sea-level rise, devastating low-lying and coastal areas around the world. But the researchers said that even though such a rise could not be stopped, it is still several centuries off, and potentially up to 1,000 years away.

    The two studies, by Nasa and the University of Washington, looked at the ice sheets of western Antarctica over different periods of time.

    The Nasa researchers focused on melting over the last 20 years, while the scientists at the University of Washington used computer modelling to look into the future of the western Antarctic ice sheet.

    But both studies came to broadly similar conclusions – that the thinning and melting of the Antarctic ice sheet has begun and cannot be halted, even with drastic action to cut the greenhouse gas emissions that cause climate change.

    So it looks as if there is now enough trapped heat in the southern oceans licking at WAIS that its irreversible.

  11. 111
    wili says:

    Thanks to all for the links to this important news about the now inevitable collapse of the West Antarctic Ice Sheet.

    Can a collapse earlier than two centuries away be ruled out completely? What does this mean for slr for the next few decades? Is the increase in sea level rise from this source possibly going to be balanced by possible decreases in the rate of sea level rise from Greenland, if, as recently reported, much of the recent melting there is due to a natural cyclic pattern?

    In any case, I find the whole thing incredibly sad. Here again, we have altered a fundamental feature of the planet we evolved on. Something that there is no way now to put back together. Something that will mean that important, now-heavily populated portions of the earth will be unavailable to future generations, requiring massive relocations and disruption, at least.

    Try looking at what happens to Shanghai and to the entire province of Jiangsu just to its north with just a couple meters of slr. Not to mention the southern half of Bangladesh, the Calcutta area, and many other such regions. These are some of the most densely populated areas on the planet, and there is now no way to prevent them becoming covered by the ocean, probably within a few centuries if not much sooner. Or are we going to spend endless resources building ever-higher dikes to keep out ever-rising sea levels from coastal areas everywhere??

    Further news wrt Antarctic (thanks to ASLR at neven’s Arctic Ice forum for finding this):

    Grace A. Nield, Valentina R. Barletta, Andrea Bordoni, Matt A. King, Pippa L. Whitehouse, Peter J. Clarke, Eugene Domack, Ted A. Scambos, Etienne Berthier , (2014), “Rapid bedrock uplift in the Antarctic Peninsula explained by viscoelastic response to recent ice unloading”, Earth and Planetary Science Letters, Vol 397, DOI: 10.1016/j.epsl.2014.04.0191 July, 2014. published online on 12th May 2014

  12. 112
    Hank Roberts says:

    The Abstract says:

    Resting atop a deep marine basin, the West Antarctic Ice Sheet has long been considered prone to instability. Using a numerical model, we investigate the sensitivity of Thwaites Glacier to ocean melt and whether unstable retreat is already underway. Our model reproduces observed losses when forced with ocean melt comparable to estimates. Simulated losses are moderate ( 1 mm per year of sea-level rise) collapse for the different simulations within the range of two to nine centuries.

  13. 113
    Chris Dudley says:

    If we consider 64 times CO2 as the outcome of economically driven BAU, it is interesting to examine what adaptation measures might be considered: Some respiratory problems might occur at that level of carbon dioxide in the atmosphere, so breathing apparatuses might be useful for infants, young children and the elderly. While the surface air pressure is already increasing, that does not help with oxygen availability since it is water vapor that is adding to the mass of the atmosphere. Average surface air temperature is warmer that the present day equator everywhere, but is below human body temperature within about 20 degrees of the poles. Some alpine valleys in these regions might have present day equator-like temperatures. Thus, adapting equatorial crops to constant light conditions might provide a source of sustenance. Precipitation may be adequate for that. However, sustaining a population of 10 billion on crops from alpine valleys at high latitude is probably not realistic, particularly since most of the population will need to live there, putting pressure of land for agriculture, so laboratory synthesis of glucose will be a needed adaptation. Fortunately, renewable energy is efficient compared to photosynthesis so reduced land area for feeding people may not be a problem. Range for meat production might be extended by switching to insects and reptiles that can survive in higher temperatures too, but just shifting to laboratory protein growth seems like the more likely adaptation. Heatwaves will likely pose a serious mortality risk so cooling methods will be needed for survival. Evacuating to alpine peaks may not be adequate so mechanical methods would be required. A much higher specific humidity would increase energy requirements for this.

    Since migration to presently uninhabited areas would be needed, adaptation requires writing off nearly all the present world economy’s value. The difficulty in reconciling IPCC WG II accounting and WG III accounting highlighted recently here would really be moot, since present value would be a total loss. National values tied to particular geography would also be destroyed. It is interesting, however, that the adaptations regarding food supply needed for mere survival, could, if BAU is avoided, be used to restore the roaming range of the buffalo in North America and let the deer and the antelope play freely again. National values might be enhanced in that situation.

  14. 114
    Pete Dunkelberg says:

    Antarctica, SLR and implications imho

    So the WAIS is collapsing right now in slow motion and will speed up as time goes by. Can SLR happen much faster than models indicate? I think so provided we continue BAU all the way to the year 2100. (imho BAU will collapse by 2050.) BAU through 2100 would create a far warmer world than our great ice sheets have ever experienced, and the Antarctic Archipelago only looks like a continent because we can’t see through all the ice. [Fretwell et al. “Bedmap2: improved ice bed, surface and thickness datasets for Antarctica”, picture.] I doubt that models more or less extrapolation from current observations tell us what would happen under blistering 2100 BAU. Hansen has a grasp of very basic physical science: heat melts ice. Why is that hard to believe? I would be glad to have a new expert post on this though.

    Wili has the sanest comment:

    In any case, I find the whole thing incredibly sad. Here again, we have altered a fundamental feature of the planet we evolved on. Something that there is no way now to put back together. Something that will mean that important, now-heavily populated portions of the earth will be unavailable to future generations, requiring massive relocations and disruption, at least.

    But you are seriously missing the human response picture if you just read RC. To get more realism you must visit Eli. You won’t like it, but do it.

  15. 115
    Chuck Hughes says:

    It seems that the science on AGW has always underestimated exactly how soon things will occur. Not that it will happen but how quickly. When it comes to the WAIS is it possible that dramatic SLR could happen much sooner than anticipated? Could we be off by several hundred years and several meters in the opposite direction?

  16. 116
    Hank Roberts says:

    > It seems that the science on AGW has always
    > underestimated exactly how soon things will occur.

    I’ve had the same feeling but would welcome pointers to research.
    Is there a meta-study of past IPCC reports discussing how each of them has looked in retrospect, and finding out what explains divergence over time? (I’d guess mostly it’s the political, er, tempering of the scientific work that makes each IPCC report appear in hindsight to have been overly optimistic/conservative — the ‘don’t scare the sheep’ approach to policy)

    I wish for a Journal of Cassandra Studies, evaluating early warnings.

    I’ve been able to find some more general work along those lines, e.g.: (Thompson-Reuters — public policy and early warnings covering a variety of development, rights, climate, and law areas)
    (Effects of Global Warming Around the World — Union of Concerned Scientists)

    The public health literature seems the place to look, e.g.“public+health”+”early+warnings”+evaluation+retrospective

    which finds among much else Mazur’s early work:

    True warnings and false alarms: Evaluating fears about the health risks of technology, 1948-1971

    which has been cited by many later papers that look worth reading:,5&hl=en&num=60

    These are the sort of questions that make me wish RealClimate had a librarian on retainer, to help figure out what’s good information.

    Is there a librarian or library intern at NASA or Columbia who could be persuaded to moonlight here for tips and gratitude?

  17. 117
    Hank Roberts says:


    The acid test of a scientific theory is whether it makes predictions that eventually come true. So consider this old prediction, from a pair of researchers in Australia and New Zealand. They were summarizing the results of then-primitive computerized forecasts about global warming:

    The available evidence suggests that a warmer world is likely to experience an increase in the frequency of heavy precipitation events, associated with a more intense hydrological cycle and the increased water-holding capacity of a warmer atmosphere.”

    That was published in 1995, and it was based on research going back to the 1980s. Fast forward to 2014.

    In the National Climate Assessment, published last week, researchers in the United States reported that

    “large increases in heavy precipitation have occurred in the Northeast, Midwest and Great Plains, where heavy downpours have frequently led to runoff that exceeded the capacity of storm drains and levees, and caused flooding events and accelerated erosion.”

  18. 118
    SecularAnimist says:

    Hank Roberts wrote: “I wish for a Journal of Cassandra Studies, evaluating early warnings.”

    Baltimore psychiatrist Dr. Kathryn Railly did some interesting research in that field in the 1990s, and wrote a book entitled Madness and Apocalyptic Visions, in which she described what she called the Cassandra Complex — “the agony of those who predict the future and are not believed”.

  19. 119

    #118–The story of poor Cassandra is indeed a powerful. I used it in connection with the Arctic sea ice back in 2010, writing:

    We’ll finally understand:  all the Cassandras were right.  We’ll understand that our position in the world is not guaranteed us, regardless of  our own actions.  That our welfare in this world is our responsibility, not God’s.  And that, by protecting our comfort, we will have imperiled our very survival.

    [Image of “Ajax and Cassandra,” by Joseph Solomon.]

  20. 120
    Chris Dudley says:


    BAU has chugged through huge calamities with out taking any notice. The twenty to forty million famine deaths in China were hardly even known in the late 1960’s. WWII kept the wheels of industry spinning at a high pitch with even more deaths going on. We may see huge suffering in the 2050’s but I doubt it would put an end to BAU. BAU ends when we decide it ends. Absent a decision, it just keeps going.

  21. 121
    sidd says:

    Re: Cassandra

    I notice that while the Joughin paper reference both Weertman(1974) and Mercer(1978), the Rignot paper does not.

    Joughin points out that the onset of catastrophically fast retreats on Thwaites “will ensue once the grounding line reaches the basin’s deeper regions”

    That grounding line bears watching. And the same is probably true of PIG, Haines,Pope, Smith, Kohler as detailed in Rignot. If _none_of these can melt on a timescale faster than centuries, then the timescale of centuries is plausible. But there is awful synergy here, from Joughin:

    “Our simulations also assume that there is no retreat of the ice-shelf front. Full or partial ice-shelf collapse should produce more rapid retreat than we have simulated. In addition, we have not modeled ocean-driven melt that extends immediately upstream of the grounding line, which could also accelerate retreat”


    “Such rapid collapse likely would spill over to adjacent catchments, undermining much of West Antarctica”

    From Rignot:

    “As shown here, the glacier grounding lines retreat rapidly, at km/yr, over the entire sector. On Smith/Kohler, the retreat rate of 1.8 km/yr is even greater than its rate of horizontal motion of 1.1 km/yr.”

    At these rates, the grounding lines reach the deepest sections of beds in decades, not centuries. The scales on Fig 3 in Rignot are in tens of kilometers, not hundreds.

    I fear Joughin model is optimistic on the timescale.


  22. 122
    wili says:

    Why does Cassandra get all the press and not Laocoon and his poor kids? Is the name too hard to say? He does get some awesome sculpture, at least.

  23. 123
    Mal Adapted says:


    the Cassandra Complex — “the agony of those who predict the future and are not believed”.

    It must be worse for people who reveal the past and are not believed, like Mike Mann or (one of my personal heroes) J. Harlan Bretz.

    If AGW deniers think climate’s been just as bad or worse before, it’s easier for them to dismiss predictions of a hot and stormy future.

  24. 124
    Hank Roberts says:

    Laccoon et al. were weather.
    Cassandra was climate.

  25. 125
    Chris Dudley says:

    In #32 I wrote: “Gavin may be able to say if the upturn in response in the right hand sector of fig. 30 of “Storms of my Grandchildren” is owing to not recognizing the limit on biosphere carbon available for feedbacks or not since he ran some of the models.”

    Getting back to this subject after a few years, I realize that does not make a lot of sense. Fig. 30 is given in forcing on the x-axis so it is what it is in terms of CO2. A doubling is just a doubling, not also its attendant feedbacks, or perhaps we might say it is the concentration in the atmosphere regardless of source.

    With the confirmation of fig 30’s growing sensitivity coming from the work of Russell et al. (2013) and new estimates of the actual reach of BAU we can now assess the value of Hansen’s chapter on the Venus Syndrome. That chapter placed a full stop on man’s activities and indeed life on Earth. That was a powerful lever for moral suasion.

    I wonder if the new situation is not even more powerful. Reduced to being packed into a few alpine valleys in Antarctica and the Northern extension of he Urals, cowering from deadly heatwaves in the summer, eating chemical swill from laboratories, when it comes time to say:

    “Let us now praise famous men, and our fathers that begat us.
    The Lord hath wrought great glory by them through his great power from the beginning.
    Such as did bear rule in their kingdoms, men renowned for their power, giving counsel by their understanding, and declaring prophecies:
    Leaders of the people by their counsels, and by their knowledge of learning meet for the people, wise and eloquent are their instructions:
    Such as found out musical tunes, and recited verses in writing:
    Rich men furnished with ability, living peaceably in their habitations:
    All these were honoured in their generations, and were the glory of their times.
    There be of them, that have left a name behind them, that their praises might be reported.
    And some there be, which have no memorial; who are perished, as though they had never been; and are become as though they had never been born; and their children after them.
    But these were merciful men, whose righteousness hath not been forgotten.
    With their seed shall continually remain a good inheritance, and their children are within the covenant.
    Their seed standeth fast, and their children for their sakes.
    Their seed shall remain for ever, and their glory shall not be blotted out.
    Their bodies are buried in peace; but their name liveth for evermore.”

    Will people not simply snicker at the thought of us and curse us?

    Ending all life on Earth, while dramatic, may not compete with nearly doing so and being held up to contempt forever more. Rather that a full stop, we are heading for an endless fermata of ridicule and hatred. None of our good qualities will be acknowledged and we will be remembered only for the destruction we wrought in full knowledge that we betrayed our progeny and secured them no blessings but only suffering.

  26. 126
    Thomas says:

    Even if we could get conservatives to admit the latest research isn’t a hoax, the oderly slow retreats discussed in the papers only contribute a millimeter or less per year to SLR. To the average Joe that doesn’t sound very alarming. Even several of these mm/year events happening simultaneously, which looks likely as we get circa a mm/year from each of several glacial systems, just doesn’t strike fear into the heart.

  27. 127
    Hank Roberts says:

    > Bretz


    2007 (from “why study Antarctica”, a rather long discussion of what might be happening);

  28. 128
    Chris Dudley says:

    A new report claims climate change is a security threat.

    “The Center for Naval Analyses Military Advisory Board found that climate change-induced drought in the Middle East and Africa is leading to conflicts over food and water and escalating longstanding regional and ethnic tensions into violent clashes. The report also found that rising sea levels are putting people and food supplies in vulnerable coastal regions like eastern India, Bangladesh and the Mekong Delta in Vietnam at risk and could lead to a new wave of refugees.

    In addition, the report predicted that an increase in catastrophic weather events around the world will create more demand for American troops, even as flooding and extreme weather events at home could damage naval ports and military bases.

    In an interview, Secretary of State John Kerry signaled that the report’s findings would influence American foreign policy.”

  29. 129
    Fred Magyar says:

    Chris Dudley @ 120,

    “We may see huge suffering in the 2050′s but I doubt it would put an end to BAU. BAU ends when we decide it ends. Absent a decision, it just keeps going.”

    Surely you jest, Dr. Dudley!

    BAU has already ended, it’s just that poor Wiley Coyote has run out past the edge of the cliff and hasn’t looked down yet.
    It’s an awfully long way down. Last year I spent 8 months in São Paulo Brazil, the city where I was born, It has a population of about 20 million and it is bursting at the seams in every way imaginable. It should be obvious why there is social unrest happening there and all over Brazil and compared to the rest of the world Brazil is still a paradise with huge amounts of natural resources. Anyone who thinks we can continue to add 4 São Paulo’s worth of people to the planet every year and BAU will end when ‘WE’ decide it ends hasn’t thought that comment through to its ultimate consequences.

    Should be interesting to watch what happens when the water runs out…

  30. 130
    MARodger says:

    GISS temperatures for April have been posted. I’m getting the feeling that temperatures are perhaps on the move upwards even before the predicted El Nino in the autumn (which will boost global temperature some months after that again).
    The last 12 months from GISS are 0.56, 0.6, 0.53, 0.61, 0.73, 0.6, 0.78, 0.6, 0.68, 0.44, 0.7, 0.73.
    The hottest 5 months within last 8 months of GISS are as a group unprecedented outside El Nino events. Five months at 0.68 or higher have not occurred together outside the 2005 & 2010 events. The full 135-year record shows only 34 such months prior to this current run.
    Thus my feelings of a pre-El-Nino upward movement.

  31. 131
    Pete Best says:

    This paper (available to read) from an article on sceptical science points to the fact that 400 ppmv last occurred millions of years ago and the ice caps were smaller and the Arctic ice sheets did not exist at all. The entire argument hinges on when did the WAIS form.

    This graph demonstrates that Antarctica’s first ice cap formed at around 700 ppmv but that this is most likely the EAIS that formed and I don’t think it is actually known when WAIS formed and so if WAIS formed later then it also could be responding to the climate and hence its worse than Greenland as Greenland has buttresses holding the ice back more so than WAIS does.

    Whatever our future 500 ppmv does look distinctly plausible as at 2 ppmv per annum its only 50-60 years away and even 450 ppmv looks like we cant avoid it now. However surely for ice sheets to respond in terms of metres of sea level rise we need a long time consistent exposure of high levels of Co2 (hundreds of years) and then surely (?) these projections of doom are not likely as we can prevent such long time exposure to high co2 levels even if we emit 500 – 600 ppmv in the short term?

  32. 132
    Paul Miller says:

    Though RealClimate’s readers might like John Oliver’s wonderful “Statistically Representative Climate Change Debate!:

  33. 133
    Chris Dudley says:

    The most morose prophet may have been Jonah, who got Nineveh to change its ways and then despaired because the retribution did not come.

  34. 134
    Chris Dudley says:

    Fred (#129),

    Thanks for the honorific. Not joking at all though. BAU does just fine with lots of misery along the way. It just needs to keep on increasing fossil carbon emissions. The theme I’ve been developing in this thread is that renewable energy gives us a much deeper reach into fossil carbon pools than we would otherwise have. Novel hydrogenation fracking using renewably sourced hydrogen to activate type IV kerogen gives us an enormous new whack at known oil source rock and access to much much more fossil carbon than usually assumed. BAU has no resource based constraints for centuries. So, it really is about a decision to bring BAU to an end.

  35. 135
    Hank Roberts says:

    A better cite for that conversation I mentioned from 2007 — mentioning Bretz, with various clips and cites for the studies that disproved — and improved — our ideas about, e.g., subglacial water as a source of outburst floods, and that drumlins get formed below glaciers and very fast. It’s a good collection for looking at how fast what we knew changed:

    The rate of change in our thinking about the stability of the Antarctic — when I was young it was thought stable for millenia to come — reminds me of how Geology 101 changed the year after I took the class.

    The ‘no known mechanism’ argument is rather threadworn by now, having failed — e.g. continental drift, and lung cancer, and climate change, none of which have yet to conclusively nail down every possible detail about what’s going on — nevertheless, what happens continues to happen.

    This is why science is worth doing — we can take some pride and joy from our success understanding the world by challenging nature: “Prove me wrong. Please!”

  36. 136

    #134–Well, he was sort of a Cassandra in reverse, wasn’t he? He hated the Ninevites so much he wanted nothing to do with saving them–and foresaw, correctly, that God might well find a way to get them off the hook.

    Hey, do you think testimony from the mouth of a whale might induce the US House to repent?


  37. 137
    Hank Roberts says:

    > Pete Best
    That PDF link goes to the cautionary

    “Note: This is a quick blog post on a specific current media question, not a review paper so I have not attempted to fully reference everything in it.

    Given that, I can see why you rely on Surely to believe that it can’t happen fast and besides someone will fix it. That’s all he’s got there — the old natural rates of change, the we don’t know for sure. Presumaly he’s got a basis for saying all that, but without cites, how can you tell?

    But more to the point, the paleo work doesn’t give us a worst case.

    Given the published work recently discussed above — pointing out the mechanisms that are pushing warm water under the edges of the Antarctic ice, and the discovery that the Antarctic minus ice is an archipelago — and the earlier discoveries from drilling that there’s liquid water at the bottom of the ice in many places already — I wouldn’t think Surely is a basis for confidence.

    Have you looked at the wind pattern around Antarctica?
    Take a look — this should be a current picture:,-90

    Surely paleo rates of change — much slower — wouldn’t lead us to expect that the deep past experienced the same rapid changes in the wind patterns, which are pumping warm water under Antarctica’s skirts now.

  38. 138
    Hank Roberts says:

    p.s., for Pete — Dr. Pearson is appropriately skeptical about some of the rate change arguments, e.g. here (I can see only the first page):
    February 26, 2014, doi: 10.1073/pnas.1322077111
    PNAS March 25, 2014 vol. 111 no. 12 E1064-E1065

    Layering in the Paleocene/Eocene boundary of the Millville core is drilling disturbance

    Paul N. Pearson, Christopher J. Nicholas

    In a study of a sediment core from the US Atlantic Coastal Plain (Ocean Drilling Program Site 174X-Millville), Wright and Schaller (1) claim to have resolved the onset of the Paleocene/Eocene carbon isotope excursion (CIE) across 13 y. Such a rapid change would require an enormous and instantaneous release of isotopically light carbon into the ocean/atmosphere, implicating comet impact. The claim rests on the interpretation of rhythmic layering in the sediment core as annual couplets but here it is proposed that they are an artifact of drilling disturbance.

    When claystones are rotary cored they can fracture into “biscuits” that spin within the core barrel as drilling progresses (2). Slurry can be injected between and around them, later hardening into featureless muddy partings. We have …

    That paper he criticizes does make an extraordinary claim, and the problem he describes might be an alternative explanation — and more and perhaps more careful drilling ought to distinguish what’s in the sediment from what’s in the cores, if the cores are disrupted during the drilling operation.

    I, um, hope he’s right about that rate of change, just selfishly speaking.
    Science includes ripping apart one another’s papers, as Peter Watts has pointed out.

    Wright and Schaller:

    Other references

    (Zeebe has also criticized that paper)

  39. 139
    jg says:

    What’s with the Lennart Bengtsson situation? Tempest in a teapot? Cutthroat “warmist” McCarthyism? It’s certainly making the rounds of denier comments all of the sudden from somewhere.

  40. 140
    Chris Dudley says:

    Kevin (#136),

    I’d heard they were already taking advice from a whale.

  41. 141
    Pete Dunkelberg says:

    When pondering whether current & soon coming climate forcing is likely to cause significantly higher sea level, think about more recent times than 33 Ma. I’ll mention and Dalziel’s papers,10&hl=en
    to suggest that only half as far back will do. But really, let’s think of the planet as it is, or at least its geology since Panama sutured.

    Sea level has been up multiple meters since then and CO2 has not gone much above 300 has it? Not close to 400, or have I missed something?

    So of course the seas will rise. It is just a question of how soon.

  42. 142
    Pete Best says:

    The issue is somewhat confusing when trying to go back in time many millions of years and many factors can interfere with the results. The article is this one:

    I took the article from this quote from the piece:

    Values similar to today (398.03 ppm for Feb 2014) were last seen during short intervals in the Pliocene some 3 to 5 million years ago, but the last time long-term mean CO2 was at this level was in the middle Miocene climatic optimum (~16 million years ago; see this blog piece by Paul Pearson for more discussion).

    Now I don’t know what is meant by a short interval in terms of the time they are specifying but it stands to reason that it has to be at least a millennium to cause ice sheets of the size of WAIS to disappear significantly (I could be wrong and it does not take such a long time perhaps but its a low probability so the main issue how much additional sea level rise will WAIS add to Greenland’s contribution over time)and hence its all reversible presently but if ocean heat is mounting to the point where it cant be stopped then that’s a bit worrying but can you get anyone to believe it?

    For all of the paleoclimatic data available to us the rate of warming must be of some significance as I have read that generally speaking the normal rate of weathering is around 13 ppmv per million years and hence humanity adding 2 ppmv per annum is very significant and warming on human time scales has to have a significance that might be unprecedented in earths humanity.

    All a bit worrying

  43. 143
    wally says:

    #128 “A new report claims climate change is a security threat.’ Doh!

    NEW? Gosh who knew? Everyone, for like 2 decades or so, that’s who. And could one not find a better credible source than the NYTs …. a proven corporate distorter of the facts and rhetoric for decades now.

  44. 144
    wally says:

    #137 “But more to the point, the paleo work doesn’t give us a worst case.”

    I think it does … only variable is the speed of approach, but all the inputs are known, the future planned emissions are already known (barring sanity appearing on earth soon) and can be calculated accurately enough to point to the outcome of 1000ppm CO2 passed circa 2100. The worst case is a major mass extinction event the 6th since earth was earth. How much worse does it have to get?

    Dr Peter Ward 2013 Lecture on Climate Change – Our Future In a World Without Ice Caps with summary, quotes, and links

  45. 145
    Tony says:


    If you think that BAU has no resource restraints for centuries, you must have missed all of the analysis about resource restraints (LTG, the 30 year update, for one) or the analysis about human boundaries or the effects of climate change.

    However, perhaps our last best hope is that you’re wrong and that limits will force the demise of our industrial civilisation to at least get some belated mitigation of the unmitigated disasters heading our way.

  46. 146
    DIOGENES says:

    I’m surprised our Windfall proponents haven’t posted this yet!

  47. 147
    Chris Dudley says:

    BAU looks like 3% annual growth in emissions. With 10 GtC emitted in 2007, an additional 10,900 GtC would be emitted by 2123 under BAU. And it seems plausible, and even likely that we can access this much fossil carbon as the declining cost of renewable energy encourages converting that energy to convenient liquid fuels in an efficient manner (using available reduced carbon).

    So, what does a smart and respected economist say about this?

    “What about the argument that unilateral U.S. action won’t work, because China is the real problem? It’s true that we’re no longer No. 1 in greenhouse gases — but we’re still a strong No. 2. Furthermore, U.S. action on climate is a necessary first step toward a broader international agreement, which will surely include sanctions on countries that don’t participate.”

    So, non-market things have to happen, but even this seem naive. For a UN based process, there are five countries upon which sanctions cannot be brought: China, France, Russian Federation, the United Kingdom, and the United States. Two of these did not even cut emissions in response to the Kyoto Protocol. Any one has the economic base to lead the world in emissions and keep BAU going. So, the UN organizational structure makes it impossible to use sanctions where they must be used to end BAU.

    Krugman may be correct that coercion will be needed, but the peace preserving options associated with UN sanctions will not be a part of the menu. He’s got the first step right: US emissions cuts, but his next step has problems.

  48. 148
    Chuck Hughes says:

    Well, Stephen Colbert seems to have an opinion about our situation. Unfortunately, it’s no joke:

  49. 149
    DIOGENES says:

    Tony #143,

    “However, perhaps our last best hope is that you’re wrong and that limits will force the demise of our industrial civilisation to at least get some belated mitigation of the unmitigated disasters heading our way.”

    Isn’t all this all really a charade? Climate science tells us we’ve already committed to somewhere in the range 1.5-2 C. Climate scientists tell us that temperatures in this range are ‘dangerous’, using variants of dangerous. While none are willing to define ‘dangerous’ outright (with the exception of McPherson), aren’t they really saying that temperatures in this region have a good chance of placing the carbon feedbacks on autopilot? So, BAU or non-BAU may not make all that much of a difference, especially if autopilot strengthens considerably.

    Thirty years from now, when NYC has replaced Ft. Lauderdale as the Venice of the East Coast, and Congress is still debating whether climate change is real, the climate community may look back at McPherson the way the Religious look back at the Biblical Prophets!

  50. 150
    Chris Dudley says:

    Tony (#143),

    Yes, I misspoke having failed to do the math correctly. No constraints out to 2123 based on using renewable energy to take another whack at known oil and gas source rock.

    Now, there may be deeper non-biogenic reduced carbon reservoirs that our new renewable energy prowess would give us access to, but evidence for these is slight up to now. Non-biogenic graphite seems rare, for example. And, there may be undiscovered fossil carbon reservoirs presently under ice. Coming up with another factor of 10 gets us about two centuries of BAU. Might be there, might not. However, 256 times CO2 does not appear to be survivable for mammals. Extended exploitation of existing oil and gas fields through novel hydrogenation fracking may be the last BAU hurrah for that reason.