The Forecast in the Streets

In the “severe” scenario, the globe warms by 2.6 °C by 2040 and sea level rises about a half a meter. Scientists in 2040 conclude that the eventual collapse of Greenland and the West Antarctic ice sheets has become inevitable in the centuries that follow. Agricultural production declines in the arid subtropics and in increasingly flooded river deltas. Again to pick a random example from the report: the river systems in the American Southwest collapse, leading to impoverishment of Northern Mexico and increased migration pressure in the U.S. Resource stress in Latin American leads to a tendency toward populist, Chavez-type governments, and more extensive regions of de facto anarchy such as found today in parts of Colombia.

The “catastrophic” scenario assumes positive feedbacks in the carbon cycle to warm the planet by 5.6 °C by the year 2100, and sea level has risen by 2 meters. I feel compelled to note that if this is supposed to be a worst-case scenario, I personally can imagine worse in terms of sea level rise. In the social realm the crystal ball gets murkier as the report progresses from expected to severe to catastrophic, but one important ingredient in the prognosis for the catastrophic scenario is the migration of millions of people, a scale unprecedented in human history, potentially enough to undermine the stability of civilized governance. One participant recommended that we check out the movie Mad Max, only imagine it hotter.

There is far too much in this report for any sort of summary really to cover, and anyway I’m a techie rather than a touchie so my retread wouldn’t do the original report justice, but you get the idea. Results from the IPCC are summarized clearly, including regional climate projections, but the point is also made and discussed that climate forecasts tend to be in general conservative. In the arenas in which I have some competence to assess, the judgments the authors have made seem measured and fair to me. The report is authoritative and very meaty, bringing an astonishing array of perspectives and insights to the table. One could read this report and nothing else, and come away with a considerable expertise on the potential impacts of climate change. I highly recommend it to the readership of realclimate, and I look forward to reading your comments.

Thanks to Hank Roberts for digging this up.

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363 comments on this post.
  1. James:

    I think those of you invoking peak oil (or peak coal) as salvation from the worse effects of AGW are missing a rather obvious point. What happens if we continue merrily along the current path of economy & critical infrastructure depending on fossil fuels? Peak oil causes major disasters, no? Whereas if we start seriously weaning the world off fossil fuels in order to mitigate AGW, most of the peak oil problems go away. IOW, it’s not peak oil that will save us from AGW, but AGW mitigation that could save us from peak oil.

  2. Stephen Mulkey:

    Would someone please explain Figure 1 in this document? I have gone to the hurricane reanalysis website, and I cannot find this figure or data to support this figure.

  3. Susan K:

    We know that humans can’t think at a concentration of 1000 ppm CO2.
    When do you scientists think we might get to 1000 ppm, worst case scenario? By 2200? or 2300?

    And what was the CO2 level in the juraissic or eocene?

  4. danny bloom:

    One thing I don’t understand, with all these reports out there saying that a Mad Max scenario might happen one day in the far distant future, might, mind you, not will, but might, why are no think tanks issuing reports now about how people might live in those distant years, say 2500? Why is no one discussing polar cities or actual real sustainable northern retreats where people might have to live to serve as breeding pairs in the Arctic, in Lovelock’s famous words? Why is there no discussion about this very real possibility except on my lone blog, which everyone here ignores, in addition to not replying to my polite emails? Are we ourselves in denial, too, about what may come? I would love to hear an answer one day. Meanwhile, for those interested see my ideas here:

  5. Donald Oats:

    Re 42: Tex, temperature data at CRU gives a realistic view of the warming over the last century or so. You can download it and play around with it if you so wish, but before drawing any conclusions about it you should read the scientific articles that explain the steps in going from raw, instrumental data to the downloadable data. It is a good example of the care required in a scientific field (I mention that because too often people of a cynical bent towards climate science see the fine judgement in data preparation as deceitful manipulation – it’s not).

    CRU links:
    1) Overview of Temperature statistics:
    2) Recommended (essential) reading for 1):

    3) Top level access to various data sets:

    Snooping through various scientific articles and the RC website Archive should lead you to a larger collection of data sets.

    Have fun,

    Donald Oats, Murray Bridge SA (PS: I’m not “Don” 43)

  6. Chuck Booth:

    Re: #53 Susan K

    The reference you cited states that at 1000 ppm CO2 “Prolonged exposure can affect powers of concentration” – that is not quite the same as saying someone “can’t think.” Regardless, other sources put the threshhold for cognitive effects at a much higher (at least 10X) level, for example:

  7. Craig Allen:

    Your exaggerating a little Susan. That’s the level at which thinking starts to become impaired. Still, it’s pretty scary to think that we may be able to push it that far. If there is a chance that once feedbacks kick in we may not be able to keep from going beyond this, then it would be prudent to widely publicize this fact. Mind you, the oceans are likely to be severely affected by acidification at those concentrations, and that doesn’t seem to faze people overly.

  8. Eric (skeptic):

    The authors leave out some detail, I believe that was done to make a point. They are correct in stating that the farmers were inexperienced and used to an unusually wet period. They are also correct in pointing out that the droughts were rather routine for the region.

    But I believe their conclusion that ecological ignorance was the primary problem is not correct. From this link: it was the politics of land allocation that was the primary problem. Essentially the farms were too small to diversify and withstand the drought. My personal opinion is that the story of the Dust Bowl points out the lesson of resiliance which the report appears to dismiss as a solution on page 27 due to “more crowded circumstances” without an explanation of why that decreases resilience.

  9. Chuck Booth:

    Re 53 Susan K
    “And what was the CO2 level in the juraissic or eocene?”

    According to Pagani et al (2005):

    Atmospheric CO2 concentration “ranged between 1000 to 1500 parts per million by volume in the middle to late Eocene, then decreased in several steps during the Oligocene, and reached modern levels by the latest Oligocene.”

    Science 22 July 2005:
    Vol. 309. no. 5734, pp. 600 – 603

    Fortunately, no humans were forced to breathe that atmosphere.

  10. Jim Eager:

    Re Hank @ 44: “Those commenting here — care to say if you’ve read the report described in the original post?”

    I did a quick scan through it earlier today and reposted the link to several other discussion lists, and I’ve since read through half of it more carefully. Thanks, Hank, for bringing this to David’s attention, and to David for flagging it.

  11. John Mashey:

    re: #51
    I mentioned this in another thread, but really:

    Kharecha & Hansen, “Implications of “peak oil” for atmospheric CO2 and climate”

    covers this pretty well. They certainly don’t say Peak Oil saves us….
    Of course, if in 2100, somebody wants to build dikes or sea walls, they’ll likely be doing it without (much) petroleum….

  12. Hank Roberts:

    Danny, I’m most grateful David decided to read this, I sure couldn’t evaluate it, and only stumbled on it myself (hey, those who can’t teach, proofread; those who can’t proofread, hunt and gather (grin)). It’s really not been much reported.

    David’s writeup is the only one I know of by someone who’s read through the paper and thought about it. I hope others will.

    I find indexes for sites like milnet, Navy Postgrad thesis collection, and so on almost daily will, if queried, turn up climate publications I never heard about — that makes me really hopeful about the level of competent attention being paid, quietly, to the science there.

    Stephen, re that image, did you read footnote 101? I didn’t find the exact image but found sixty-odd hits at the referenced site, didn’t have time to look further tonight, they might have an image directory; after the holiday someone there might respond if asked.

    I’d guess the chart may be drawn from the then ‘in press’ article now here:

    I tried a global search for the image and happened upon a similar document and discussion from a German climate council advisory group here:

  13. Hank Roberts:

    Stephen, looks like users do their own charts (and that’s what Fig. 1 says, ‘data from’ that site), and you need a login for access to the data sets, start here:

  14. Edward Greisch:

    My reply to 8 Danny Bloom is:
    Forget the polar city because that requires 15 to 20 degrees centigrade of warming, and we go extinct at 6 degrees C of AGW. Air mixes well over short times, so you can’t avoid death by hydrogen sulfide [H2S] well before your polar city becomes possible as you imagine it. Of course, you could marry an Inuit and take up stone age whaling and fishing, but that won’t get you past the H2S.

    The most realistic Plan B is Move to Mars and wait it out. This will not be a short wait. Figure on your distant descendants returning to Earth in thousands to millions of years. I joined a group called
    “Lifeboat” at
    See also:
    LiftPort is a company formed for the purpose of building a space elevator. A space elevator is like a vertical railroad. Riding the space elevator will get you into space safely and for a reasonable price. If you go all the way to the end [62000 miles straight up] you can fling yourself to Mars by letting go at the right moment. The reason we are not building a space elevator already is that we don’t know how to make carbon nanotubes simultaneously long and strong. They are strong enough in very short pieces, or long enough in very weak pieces. LiftPort needs the world’s greatest synthetic chemist to synthesize long strong carbon nanotubes or diamond nanowire for the 62,000 mile long cable. Do you know any candidates?

  15. pete best:

    Re #39, Ray, I believe that total world FF reserves are taken into account. As I have already stated the amount of FF required for so called dangerous climate change for the first world of 3C requires some 550 ppmv of CO2 and we are nowhere near that level as yet and will not be for 60 or so years. Recent work puts peak FF between now and 2020, peak gas and coal around 2040. Coal to liquids just burns coal faster, gas to liquids burns gas faster, it is all FF burning at the end of the day and as we may not have anywhere near as much FF as we currently believe, hence the slight misgivings over the IPCC 2001 FF projeections of 1600 to 2000 Btoe when in reality 400 to 800 Btoe is more likely.

    Re #51, James, I have not doubt that transcontinental grids and sustainable power across continents via solar, wind and storage via hydro electric can provide substantial amounts of power via these DC enabled grids and I also believe that the EU is prototyping one via a recent report I read. However they speok of 20% of the EU’s power coming from this source which is a lot but not enough.

    Politicially everyone currently knows that FF reign supreme, via lobbying and finance. Changing this slowly over time is the issue but if we suddently hit peak FF when no one thought we could then maybe we are not moving fast enough. Politics is complex and large scale changes are probably required in the energy and automobile sectors or industry but these sectors have billions/trillions invested in it so change will take a large part of a century to achieve.

    Be prepared for Green fatigue amongst the populace because even if everyone believes in AGW and demands action, it takes decades to achieve significant change and people won’t like green taxes and the curbing of theire energy intensive lifestyles.

  16. Danny Bloom:

    IMHO, ”The Age of Consequences” report is very important. I cannot download it so I have not read, but from the summary, I see there are three scenarios. One is soso, one is pretty bad, and the last one presents a kind of Max Max future scenario.

    So I wonder why so very few people have commented on my polar cities concept and blog, and why the mainstream media refuses to discuss my project. The committee that put together the AOC report said it might come to this, the Mad Max part, and my polar cities idea is to plan so that future generations can live a good positive happy life in polar cities until they can come down to middle regions again. Why is everyone ignoring me? Whenever I post, here or there or anywhere, people just read right on by me, and nobody ever replies to my emails. Hmmmm. On this blog, for example, not one person has ever replied to my emails or posted a post pro or con about polar cities. Am I so invisible?


    My goal for 2008 is a major story in the mainstream media about polar cities. If not CNN, then the BBC, if not the Washington Post, then the New York Times. If not AP, then Reuters. If not dpa, then AFP. Somebody somewhere has got to listen to me, just once. It can’t hoit, as they say in Brooklyn.

  17. Fernando Magyar:

    Susan Re # 52,
    If you Google: “CO2 levels in the Jurassic”

    You will get plenty of hits, here is a typical result:

    Roughly 210 to 195 million years ago the earth saw a major extinction event – data from the period suggests that 95% of plant species and 70% of corals became extinct. Fossil leaf studies from this period (known as the Jurassic-Triassic boundary) found that at this time there was an increase in global CO2 levels. It is estimated that at the beginning of the period, CO2 levels where three times as high as they are today. By the end of the extinction event this was seen to rise to seven times current CO2 levels. According to climate models, this led to an average temperature increase of 2-3 degrees C over approximately 15 million years. This increase in temperature lead to a huge upheaval in plant communities – biodiversity of plants was seen to decline which would in turn have seriously affected the ecosystem at the time. Periods of major animal extinction have been offset by major extinction events in plants. Thus these results suggest that rapid climate change associated with increasing CO2 levels has a negative impact upon the environment.

  18. Martin Vermeer:

    Re #5: Yes, I remember Soylent Green too. Loosely based IIRC on one of Harry Harrison’s novels (all good BTW). And Silent Running was good too. Steve Bochko directing that, better known later for Hill Street Blues.

    But mostly I remember a book by Heinlein “Farmer in the Sky” from 1945 or thereabouts (!) depicting the adventures of a young immigrant to a terraformed Ganymede. Which really is just a metaphor for Earth. Most all the issues discussed in this forum came up, including glacial isostatic adjustment, and a then still obscure (to the general public) scientific discipline called ‘ecology’ :-)

    Read it in a Dutch translation for boy scouts. Go figure.

  19. Hank Roberts:

    Need help downloading it?
    Usually rightclick or shiftclick and “save as” works.

  20. Noah Important:

    You might want to double-check those temperatures again, especially for the “catastrophic” scenario. If the BBC’s Horizon video on global dimming is right, they’re now looking at a **TEN** degree increase by 2100.

    [Response: see here first – gavin]

  21. James:

    Re #66: […my polar cities idea is to plan so that future generations can live a good positive happy life in polar cities until they can come down to middle regions again.]

    OK, if you want some of my reasons: 1) I’m not that interested in future generations, I’m interested in ME; 2) I’m far more interested in preventing the problem than in even moderate coping stratagies, let alone extreme ones like yours; 3) I wouldn’t be interested in living in a city, polar or otherwise; 4) What happens to the rest of the biosphere while humans are tucked away in their polar refuges, and can humans survive the effects of that?

  22. Ray Ladbury:

    Edward Greisch says, “The most realistic Plan B is Move to Mars and wait it out.”

    Uh,…no. First, the energy required to lift even a viable genetic population of humans from Earth to Mars is simply untenable. Hell, Edward, we can only get a tiny probe to Mars every 2 years now when the orbital configuration is favorable. And 1/3 of probes sent to Mars fail. Second, if they got there, they could not survive due to:
    1)lack of energy resources (remember solar flux is 4x lower even when there are no dust storms)
    2)lack of infrastructure
    3)the inhospitable environment (cold, lack of oxygen, liquid water, etc.)
    4)the radiation environment

    Believe me, you’d do much better at the poles or at the equator or anywhere else on Earth at its worst than on Mars. Mars is a pipe dream. At least on the Moon, it might be possible to make occasional foraging missions to Earth for resupply. And we couldn’t even make a go of “sustaiability” in the Arizona desert with biosphere II.

  23. Don S:

    Don. Will you please outline what you believe Malthus’s contributions to be, so that we can begin to understand your assertion that he was wrong? Was it his economics, or his discovery of the implications of exponential population growth versus growth of resources (an idea that led to much of the sciences of ecology and evolution), or his sociology, or his politics, or what else that was wrong? Or, was it everything that he wrote?

  24. Lynn Vincentnathan:

    #66, Hi Dan, I have emailed you. I suppose most people here either (1) would like to see GW mitigated and not have to think about polar cities — that’s the whole point of ranting about how bad GW could be, to spur people to action — or (2) they are denialists who would never consider that GW could get bad enough to need such wonderful polar cities.

    I remember in the 70s some people talking about “arks” — small, self-contained communities raising their own food that could survive the environmental devastation that would surely be upon us sometime in the future. Luckily we are still hanging on without having to live in such “arks,” though they still might be needed in the future — inland, polar and near-arctic circle “arks.”

  25. Mark R:

    Finally, finally. Real Climate addresses the other third of the equation: the human social factor. This along with the actual climate system of ocean and atmosphere, and worldwide ecosystem degradation are all intimately linked together. Human forcing of climate, along with the devouring of living Nature, will ensure that the complex abstraction that is human society will collapse.
    While I respect the scientific nature of this site, it is imperative that all three aspects be discussed and acted upon in concert. In fact, it is the common ignorance of the consequences of the other two factors which enable the average person as well as politicians and the holders of wealth and power to disengage from the climate issue, to disparage and dismiss it, to obufscate and deceive.
    To Consider only the hypothetical impact of climate change alone minimizes the possibility of catastrophic effects, in the physical world, the biosphere, and human society. Thus, I hear ignorant comments all around me–due to superficial understanding of the looming consequences.
    I feel that within fourteen years, the pressures on human society will cause our civilizations to implode. It may not be total, but it will be the start of the unraveling of human “achievement.” Lack of another energy source after oil supplies diminish will mean that the human population will have to rapidly decrease–billions will starve. Nitrogen-enriched crops will be harder to come by, and the free ride from oil energy will be gone.
    Looking at the US, a century of adulation and obeisance to the automobile has created a society which cannot function without it. We do not have fifty years to retool the physical infrastructure of the US, which means that there is no way to make a non-traumatic transition to another way of living. If the grasslands of the world are desertified, which it seems likely they shall be, there will be no large agricultural lands to continue abusing with industrial agriculture. China will absolutely refuse to change the course it is now pursuing until the northern half of the country suffers complete environmental collapse. This will come sooner than later with the de-glaciation of the Tibetan Plateau.
    Fantasies of Arctic cities will not come to pass; any event which throws the lives of billions of human beings into chaos will cause the collapse of any and all social order. Those who survive will live in “afghanistan,” where not one brick stands upon another, the weak are pushed aside, exploited, or killed, and only capable young men with a weapon prevail.
    One cannot muse about climate change without examining its impact upon ecosystems as well, including the loss of most coral reefs and oceanic life forms, the emptying of the skies of avian life, the loss of the Amazon rainforest, general extinction, and loss of rare and precious diversity.
    The polar bear is the current poster child of climate change-driven extinction, but most people are so disconnected from the natural world that this fact becomes just another bit of background static, drowned out by the diversions of entertainment and advertising.
    Catastrophic physical changes cannot be ruled out. When we have physical proof of devastating floods from breaking ice dams, both in the Washington scablands and from glacial Lake Agassiz, how can anyone suppose that other temperature-related events won’t also be soon occurring? We visited the Canadian Arctic coast two years ago, at the Mackenzie Delta, and the entire “land” there was ice frozen solid, with some dirt in it for marbling. Surely, those methane clathrates will let go at some point.
    Scientists have a duty to step outside the rigorous bounds of their discipline and start shouting. Nothing has yet changed, and we are all headed for disaster.

  26. Peter Houlihan:

    Answer to #27 and #52.

    Most of the data in the figure are consistent with the graphs presented in Landsea, C. W., 2007 : Counting Atlantic tropical cyclones back to 1900 EOS, 88,197&202.

    The differences are:

    1) That the data is further extended back an additional 40 years to 1860.

    2) The data is smoothed using a ten year running average.

    There’s lots of raw data available on the Hurricane reanalysis website and I’m guessing they used the latest 1840 to 1910 data to provide the missing years from Landsea’s pub. The hurricane reanalysis project goal is to deal with biases in tropical storm data sets related to changes in instrumentation.

    I am not sure why this graph would cast doubt on the credibility of the entire report. My biggest problem is that they didn’t do a better job of referencing and captioning it.

  27. Jim Cripwell:

    Ref 42 If I might add to David’s reply. I routinely visit 4 sites each month. The first three are
    Each month a new figure is added, usually during the first, second and third weeks of the next month, respectively. Other data are available. For example if you substitute nh and sh for gl in the third URL, you will get data from the northern and southern hemispheres.
    The fourth site is
    This site gives a comprehensive review of what the month’s weather was like. I have given the latest data; change the 2007/nov as appropiate. The data is normally available in the 15th of the next month, but if you try and access the site some time after the 1st of the month, it will tell you when the data will be available.

  28. SecularAnimist:

    Danny Bloom wrote: “with all these reports out there saying that a Mad Max scenario might happen one day […] why are no think tanks issuing reports now about how people might live in those distant years, say 2500? Why is no one discussing polar cities or actual real sustainable northern retreats where people might have to live to serve as breeding pairs in the Arctic, in Lovelock’s famous words?”

    I’ll speculate about the reason. Such “sustainable retreats” will have a carrying capacity sufficient to sustain only a tiny percentage of the Earth’s current human population. Perhaps only one percent. And who will that be? It will be the Earth’s ultra-rich, ultra-powerful elite, the “top one percent”, who command the wealth and resources required to construct and operate nuclear-powered, climate controlled enclaves in the Far North, and defend them with private mercenary armies. The rest of the Earth’s billions of humans will perish, surely beginning with the poorest, but the middle-class and “merely” rich people of the industrialized nations will perish as well when the rising tide (literally and metaphorically) of climate chaos leads to the collapse of modern societies.

    So, discussions about building these cities are probably in fact vigorously underway, in certain circles; but those discussions are not for the general public to hear or participate in. Indeed the agenda of those “certain circles” is that the public must be “protected” from the truth about global warming and climate change, so that they will continue business as usual (ie. shopping) and continue to drive the machine known as the “consumer economy” so it will continue to enrich the rich for as long as possible. They are well aware that they are going to need as much wealth and power as they can possibly accumulate to survive what’s coming. The last thing they need is for “consumer confidence” to drop because people are worried about having to evacuate Florida and move to the Polar Circle.

  29. Ark:

    @Pete Best. 400 Gtoe of total FF reserves is a very extreme view; that’s only 36 years at present consumption rate. I see that you have now moved up your range to 800 Gtoe (#65). In my opinion, the PeakOil movement has come up with credible information on the oil reserves, but their stories on coal reserves (let alone methane hydrates) are not very mature yet. Anyway, I’d hope you’re right; it would be a strong support for the measures that have to be taken to avoid even more dangerous climate change than we’ve already entered into. 2C (let alone 3C) is by no means the temperature level where strong negative consequences start, it is the extreme limit of risk that society is as present willing to take, given the perceived difficulties of drastic emission reduction.

    Do you have a source for your statement that IPCC scenarios leading to stabilization at 550 ppm assume input of 1,600 – 2,000 Gtoe? The bundle of IPCC scenarios shown on the site that you refer to starts much lower. And do you mean 550 ppm of CO2 (which in combination with other greenhouse gases would lead to >600 ppm CO2eq), or do you mean 550 ppm CO2eq (total greenhouse gases)?

    Needless to say that required measures to cope with both peakoil and climate change are largely the same; there is little reason to compete for the first prize in the Worst (and Quickest) Global Disaster category.

  30. Susan K:

    Mark, where have you been? “Finally, finally. Real Climate addresses the other third of the equation: the human social factor. ”

    Real Climate gets it that we humans are in real peril. They are the ones who have been trying to get word out about exactly that, for all this time.

    Just because Rush limbaugh tells you something, doesn’t make it fact. Those who are alarmed are not sentimental about just one measly species, but about the survivability of the ecosystem we humans depend on.

  31. Nick Gotts:

    Re #49 (Ray Ladbury) Ray, at the end of Ch.2 of his “Essay on Population”, Malthus lays out three propositions on which his theory depends:

    “The theory on which the truth of this position depends appears to me so extremely clear that I feel at a loss to conjecture what part of it can be denied.

    That population cannot increase without the means of subsistence is a proposition so evident that it needs no illustration.

    That population does invariably increase where there are the means of subsistence, the history of every people that have ever existed will abundantly prove.

    And that the superior power of population cannot be checked without producing misery or vice, the ample portion of these too bitter ingredients in the cup of human life and the continuance of the physical causes that seem to have produced them bear too convincing a testimony.”

    Malthus perhaps could not know, but we know now that his second proposition is false: consider Japan, where population has just started to fall, and – absent some unexpected change – will do so for several decades, while it can hardly be argued that the means of subsistence are lacking. The same would apply to a number of west European countries without immigration. We also know the third proposition is false, at least if we accept artificial contraception and the equality of the sexes, which I think Malthus would regard as species of “vice”. Malthus’s main aim in the “Essay” was to refute the dangerous ideas of Condorcet and above all, William Godwin, whose “Enquiry concerning political justice” had recently been published.

    You say “Organisms either limit their population (by mating protocols, suicide, etc.) or they expand until they outrun their food chain and die back. There is no reason to think that humans are any different, and we certainly haven’t limited population.”
    The first part of this is true, but even among non-human K-selected organisms (long-lived, slow-breeding ones), population dynamics are much more complex than you appear to realise: individuals will often not breed unless and until they have the resources to give them a good chance to raise young successfully – primarily territory and nest site. This does not require group selection – it can just be a better strategy not to risk your own health this year, but build your strength and competence and wait. With human beings things are still more complex, because our cultural complexity makes it quite possible for genetically maladaptive behaviours to persist over long periods. Malthus thought we have an irresistible instinct to reproduce, but as a (sadly deceased) gay friend of mine said “I’m quite willing to be a slave of my gonads, but not of my genes.” Animals, and particularly people, are not particles, and approaches to social science which treat them as if they are (neoclassical economics, sociobiology/evolutionary psychology) are dangerously simplistic.

    As for “we certainly haven’t limited population”, well we haven’t, yet, but it is quite feasible that world population will begin to decline, without any disaster, around 2050. Urbanisation is probably the main factor that has roughly halved the rate of increase since its peak in the 1960s, but increased education and status for women, and availability of contraception, have also contributed. None of this means the current world population is not dangerously high, nor that we don’t need to work to halt growth as early as possible, nor that a Malthusian catastrophe could not occur, but in simple terms, yes, Malthus was indeed wrong, and the admirable clarity with which he laid out his view enables us to say where he went wrong.

  32. Ark:

    @Pete Best. Following my previous comment (#79) I have done some digging myself. Somebody correct me if I’m wrong, but this is what I figured out.

    The IPPC “typical business-as-usual” scenario A1B uses 65 ZJ of fossil fuels in the period 1990-2100; that’s 1550 Gtoe (or 110 years at an average rate of 14 Gtoe/yr, that’s 25% higher than in 2006). BUT: this leads to very high greenhouse gas concentrations: 850 ppm CO2eq.

    If this is correct, it means that your statement that IPCC “needs” 1600-2000 Gtoe to come up with 550 ppm is way off the mark. It probably means that even “your” 400-800 Gtoe could do the job.

  33. Ray Ladbury:

    Mark, While everyone here shares your concern, there is the question of exactly what evidence forms the basis for your conclusions–or indeed for the conclusions of this report. Increased Atlantic storm activity while a very real possibility, is not an established consensus proposition. Likewise with the scenarios that lead to collapses of agricultural productivity and increased disease. They are very real possibilities, but we really don’t know enough to even assign probabilities to such occurrences. In fact, I believe this is one reason why most prognostication has dealt with sea-level rise, since it is pretty much a lead-pipe cinch at some level.
    David’s introduction makes it very clear that societa and biological consequequnces rely more on regional climate models, rather than global models, and there is much more uncertainty at the regional level. See Rasmus’s summary from August 2007:

    Scientists feel most comfortable doing science, and crystal gazing is not science. That does not mean that such prognostications are not useful as a wakeup call, or as a way of prioritizing resources for mitigation/adaptation. However, we have to realize that the more detailed the prediction, and the farther into the future we project, the murkier will the crystal become.

  34. Fabien Bulabois:

    This recent article from a UK Times columnist may provide a pertinent psychological analysis of the climate change debate.

    … Will global warming, as predicted in detail by what the politicians call The Science, raise sea levels as high as the horses’ bridles? For this, too, is (I sense) part of the hunger for apocalypse that characterises our generation. Tens of thousands of the elite of politics, the media and the universities, and hundreds of millions of Western citizens vaguely uncomfortable about the way we live now would actually be a tiny bit disappointed if planetary temperatures started to drop. This doesn’t mean global warming isn’t true, but shows that maybe we want it to be true for reasons not of the head but of the heart and conscience. A dangerous background for the development of scientific reasoning…

    [Response: This is also discussed in Kerry Emanuel’s book a little and in my review of the same. There are multiple non-scientific worldviews (including the one alluded to by Parris), but these are the continual background against which science progresses. Science is what allows us to cut through our psychological prejudges – and that’s why it’s so powerful. – gavin]

  35. S. Molnar:

    Hank, I haven’t had a chance to read the whole thing yet, but I’ll give a tentative review. Following up on my comment #1, I find the political views embedded in the report to be very much Washington inside-the-beltway conventional wisdom. For example, we have in boldface “the two great security threats of the day— global climate change and international terrorism waged by Islamist extremists.” Even allowing for the implicit understanding that the author meant only threats to the U.S., the assertion is highly debatable (but please don’t debate it here – I’m only illustrating their world view), but proclaimed as fact.

    Following up on the Latin American point I raised in my previous comment, I find the report lacking any depth of understanding of the non-English speaking Americas, unlike the report linked above by Stefan. They even use the peculiar phrase “Central and Latin America” as if Central America is not part of Latin America. The WBGU report, by contrast, divides Latin America into climatological impact regions and then discusses individual countries within these regions. (What? Chile has a more stable democracy than some of its neighbors? This would be news to CSIS and CNAS.) I don’t doubt the quality of work of the climate experts, but for those portions of the report I have read the conclusions drawn by the so-called “national security experts” strike me as rubbish. I’ll keep plugging away, but I highly recommend the WBGU repot (which I have also not yet finished).

  36. Susan K:

    Is it possible for sea level to rise in some areas and not others?
    I see that some islands in Southeast Asia, Alaska, etc are going under. But little change is seen in sea levels in some other part of the world: just a couple centimeters or whatever. What is the explanation for that difference?
    How is it possible for sealevel to not rise evenly?

    (Thanks to all for your replies re my 1000 ppm CO2 question.)

  37. Steve Reynolds:

    David: I don’t actually find figure 1 in my copy. There’s a page that won’t display but gives an error, page 40, maybe it’s there.

    [Response: Yep, the page numbered 37 is actually the 40th page in the file, the one that won’t display on my computer. David]

    Figure 1 on page 37 of the report shows named tropical storms from 1860 to 2005 with the following caption:

    The running 10-year average of
    annual frequency shows a dramatic
    and abrupt increase above the
    previous maximum observed in the
    mid-1950s, previously considered
    extreme. DATA SOURCE: The Atlantic
    Hurricane Database Re-analysis
    hrd/data_sub/ re_anal.html.

    What is very misleading about this figure:
    It shows a high S/N monotonic increase in storm frequency since 1987.

    [edit – please do not assume motives for which you have no evidence whatsoever]

  38. Jeffrey Davis:

    Malthus is the most patient of economists.

  39. pete best:

    Re #79/82. 550 ppmv is end of century levels at current 2 ppmv per annum, or 380 + 180 = 560 ppmv. Peak Oil could be only 5 years away and peak gas and coal around 2040 which means topping out at around 460 ppmv.

    Dr Rutledge from Caltech gives the low down here. He states that global oil production is higher in 2100 on IPCC scenarios then now whcih is simply impossible. The same goes for oil and gas.

    Its good work and appears to show some common sense.

    Regardless of amounts, there is simply not enough FF to take us all the way to 2100 as we are now, ie BAU. It takes BAU scenarios until 2100 to put is into dangerous climate change of 3C and more. 2c is 450 ppmv and that appears to be the limiting factor.

    850 ppmv would mean 3 ppmv per annum 90 x 3 = 270 + 380 = 650 or 4 ppmv giving 90 x 4 = 360 + 380 = 750 ppmv which I thought was not on the radar at all. I thought that BAU was 550 ppmv by end of century but maybe natural CO2 release from current natural sinks such as the Amazon and the oceans take up less or even begin to release its own CO2 stores much like permafrost might.

    25% higher Co2 emissions than todays BAU are unlikely by end of century or mid century for that matter, hence if we are releasing 10 Gtoe now then comes 90 years time it will 900 Gtoe equivilent but demand is rising the real world. If we only have 400 Gtoe left as statedin the video (800 gtoe was a 50% error margin I made up) then we cannot even get to 550 ppmv was my main point and peak FF is going to cause us serious trouble way before AGW becomes serious enough to get us all panicking.

  40. Ray Ladbury:

    Nick #81, while I hope that Malthus was wrong about his proposition #2, I would say that the jury is still out on that. After all, we have had population growth slowing and in some countries actually reversing sign, but this is a very recent trend, and the attribution of the trend to “prosperity” to “increased education for women” or to “the high expense of raising children” etc. is somewhat tenuous. Malthus, himself provided an out–moral restraint. And if, indeed, the high cost of raising children is responsible, then it could be argued that scarcity of “sustenance” is behind it, since the children will not be able to sustain themselves without that college education.
    However, it is not even clear whether the trend of falling population will be sustained in the long term. Remember that falling population poses its own economic problems–e.g. increased risk of deflation, supporting aging populations with a decreasing workforce, etc. Moreover, if we find that prosperity is responsible for decreasing fertility, how will humans respond as that prosperity is reduced. Again, we want to think that humans are somehow different from other animals. Unfortunately, we have yet to show that that large bulge of neurons on the end of our spine serves any evolutionary purpose.

  41. David B. Benson:

    From the discussion section of John Skilling’s paper Foundations? in 27th International Workshop on Bayesian Inference and Maximum Entropy Methods in Science and Engineering, AIP Conference Proc. #954 (2007):

    … We always process models of the truth. We do not see “the truth”, and even if one of our models happens to be true, we would never know it. We may motivate ourselves by aiming to search out the truth, but it is a myth. …
    Science is commonly, but wrongly, perceived as truth seeking. Actually, it is a quest for predictive connections, and those connections are of practical value. In science’s war with the irrational, we should fight on the firm ground of practicality, and not on the weak ground of some supposedly-authoritative knowledge of mythical truth.

  42. catman306:

    Lynn Vincentnathan (or whoever might know or care to take an educated guess)

    I think I remember you writing you had a degree in anthropology. I’m wondering how many civilizations (world wide) have come and gone in the past 10,000 years. I guess the number is in the high hundreds. There’s nothing new about civilizations coming and going, usually because of self induced changes in local climate and soil or outsiders bringing disease for which the civilization has no immunity. Because we have a global civilization, if we fail it will probably be a global catastrophe rather than a local one.

  43. Nick Gotts:

    Re #90 (Ray Ladbury) Ray, sorry, but this is just flannel – quite uncharacteristic of you. Malthus said population always increases when sustenance is available, and it doesn’t. The fact that declining population has its own problems is true but irrelevant, and of course it is not certain the trend toward falling population will continue – because people and societies are complicated. Neither alters the facts that Malthus was wrong, that we know how to go about decreasing birth rates, and that in many countries, these are now below replacement level. Why are you so determined to deny or ignore these facts, and to be pessimistic about this?

    “Again, we want to think that humans are somehow different from other animals. Unfortunately, we have yet to show that that large bulge of neurons on the end of our spine serves any evolutionary purpose.”

    Of course humans are different from other animals. This is quite clear from our demographic history alone: no other mammal has a global distribution apart from our symbionts and parasites; none has a 10,000 year history of increasingly uneven distribution; none has a long history of more-or-less monotonically increasing population growth rate (from way back in the Palaeolithic to the 1960s), followed by a reversal of this trend – without a rise in death rate. As for “evolutionary purpose” – what do you mean? If you mean “adaptive function”, of course the brain has an adaptive function – you don’t suppose we’d spend 10% of our energy budget on it, kill a significant proportion of mothers because it’s so big at birth, still have to be born in a near-helpless state, and spend 20 years growing it rather than breeding if it didn’t, do you? If you don’t mean adaptive function, what do you mean?

  44. Nick Gotts:

    Re #92 (catman306) “I’m wondering how many civilizations (world wide) have come and gone in the past 10,000 years. I guess the number is in the high hundreds.”

    Impossible to say, because “civilizations” are not discrete objects with clear boundaries. I dare say you could come up with any number from about 10 to several thousand.

  45. Bruce Tabor:

    The quote from Machiavelli’s “The Prince” on page 5 of the document pdf is sobering and, it seems to me, a warning about letting scepticism become denial:

    “The Romans did in these instances what all prudent princes ought to do, who have to regard not only present troubles, but also future ones, for which they must prepare with every energy, because, when foreseen, it is easy to remedy them; BUT IF YOU WAIT until they approach, THE MEDICINE IS NO LONGER IN TIME BECAUSE THE MALADY HAS BECOME INCURABLE; for it happens in this, as the physicians say it happens in hectic fever, that IN THE BEGINNING of the malady IT IS EASY TO CURE BUT DIFFICULT TO DETECT, BUT IN THE COURSE OF TIME, NOT HAVING BEEN EITHER DETECTED OR TREATED IN THE BEGINNING, IT BECOMES EASY TO DETECT BUT DIFFICULT TO CURE. THUS IT HAPPENS IN AFFAIRS OF STATE, for when the evils that arise have been foreseen (which it is only given to a wise man to see), they can be quickly redressed, but when, through not having been foreseen, THEY HAVE BEEN PERMITTED TO GROW IN A WAY THAT EVERY ONE CAN SEE THEM, THERE IS NO LONGER ANY REMEDY.”

    [My emphasis]

  46. Jason:

    My take on peak fossil fuels and climate change is as follows:

    SRES over-estimated the economically extractable fossil fuel reserves by a wide margin.

    Based on SRES, WGI uses higher than achievable emissions rates for models. However, WGI models don’t include the long-term feedbacks from vegetation dynamics, and apparently these are very important because…

    WGII looks at potential impacts from WGI outputs, and many of the effects expected later this century are already happening.

    Therefore, although fossil fuels are much more limited than SRES believes, what we already have burned is having a greater effect than expected.

    So, while I once hoped that peak fossil fuels would come in time to save us from ourselves, this doesn’t appear to be true. A real bummer.

  47. Bruce Tabor:

    It is slighly disconcerting that the catasrophic scenario “projects” out to 2100, while the severe and expected scenarios deal with the world in 2040. I see the logic of this approach in that the catastrophic scenario assumes natural feedbacks are engaged and it is assumed these will take some time to have an effect. Is this a reasonable assumption?

    I take it that “Severe” is basically a worst case (or near worst case) for 2040. Presumably different high-end emission and feedback scenarios will make little difference by then.

    Do you (David and others) think that climate change and particularly sea level rise have a reasonable chance of being worse than “Severe” by 2040?

    (This is partly a selfish question as I will probably be in retirement by 2040 and my kids will be having their children. It is extraordinary how little impact scenarios for 2100 have on one’s psyche! I think it partly explains the lack of political action on climate change.)

  48. Jason:

    With respect to earthquakes and volcanism.

    My limited understanding is that the break up of the largest Pleistocene ice sheets dramatically increased the frequency and severity of earthquakes and volcanic activity.

    This was due to the “reshaping” of the Earth caused by the redistribution of the ice mass. Continental plates rose under the former ice sheets and sunk along the peripheries. Oceanic plates now under the stress of a deeper water column sunk.

    The increased earthquake activity in Greenland makes me think a similar, though perhaps less dramatic, process will unfold as the remaining ice sheets melt and fragment and slip away.

    I am wondering if anything is written about these possibilities, or even if it is brought up in the report?

    On a related topic…dams bursting on ice sheets may also cause gushes of water that form large waves, possibly leading to tidal waves. So ocean levels don’t just rise slowly, like filling a bath tub, but can do so violently as large influxes with a lot of kinetic energy slosh around an ocean basin. What would matter, it would seem, is whether lakes form on Greenland and Antarctica, how high they are above sea level, and how far they might travel before hitting the ocean. Big lakes, high and far from the ocean could break out and form huge waves. Is this considered a possibility for either of the large existing ice sheets?

  49. John Mashey:

    #66 Danny:
    You asked, and I hate to see passion wasted, so:

    I’ve looked at your websites. I’ve seen your Lovelockian posts in numerous blogs (like Inkstain in May) including 9 here in RC, spread across 6 threads, such as “Start Here”.

    You insert “Polar cities” into at-best-tenuously-related threads, and then it lies there like a many-days-old fish, usually ignored.


    It doesn’t help people gain new insights, it’s not particularly actionable, and even if it were, I’d protest any of my governments spending any money on it. As city planning goes, the sketches in your website look like early storyboards for Star Wars movies, and as for seeing a big tree in a greenhouse and being told food will be grown … well, I’m not excited, much as I love trees and have grown a lot of food.

    a) Posting this in blogs that focus on:
    – scientific understanding
    – scenario modeling
    – energy/policy/economics
    – actionable ideas to solve problems
    just isn’t going to get a lot of interest.

    You might go hunt up more futurist, speculative blogs/bulletin boards.

    b) OR Why don’t you redirect your energy to writing a science-fiction book, or creating a videogame concept and selling that? Those can be compelling ways to get ideas out, if they’re well-done. Personally, I think the whole idea is pretty bogus, and I don’t need to spend another minute on it, but that’s just me.

    c) You are running a marketing campaign for an idea. When people do that, they normally set some goals, and if the campaign isn’t working, at some point they quit and try something else. Consider “I will get or by some date or I will quit this for good.”

    I have seen cases where people get on some idea, and then spend years pushing it, with minimal results, and just don’t accept that no one cares. Don’t do that. Some ideas are really worth fighting long fights for, but many aren’t.

  50. David B. Benson:

    Jason (98) — Not really. The tectonic forces responsible for major earthquakes (and also for volcanoes) are far vaster than the fairly minor contribution of adding or removing ice sheets. Such changes probably affect the exact timing of the extreme events, but are not the ultimate drivers.

    Minor earthquakes and also landslides can well be caused by quickly changing the load of water or ice. These are common when the reservior behind a large dam is being filled.