Field notes from a Nature Conservancy meeting

*[For those interested in slogging through it, there’s a video of our session, here. It’s not just about me. There is also some really interesting stuff from Nature Conservancy staffer Jonathon Colman and from the folks who started the conservation clearinghouse and collaboration websites and, as well as a demonstration (not altogether successful) of the emerging virtual reality conferencing technology which (when it works) might help all of us travel to conferences less often. A word of advice: skip all this and instead take a look at the Keynote lectures, by far better orators than me: Mark Tercek, Nature Conservancy CEO, Jerome Ringo, Apollo Alliance President, and CARE C.O.O. Steve Hollingworth

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107 comments on this post.
  1. John Atkeison:

    The “2°C/450 ppm numbers” points are very important.

    I was reminded when evacuating for Hurricane Gustav that sometimes you must make very important decisions about what direction to take well before the needed information is available, but the best immediately available info can be vital.

    John Atkeison
    New Orleans, LA, USA

  2. Chris Colose:

    Thanks eric

    Setting these kind of limits is practical for policy decisions, but I’m not necessarily sure what it means for climate, ecology, etc. Making the sensitivity of arctic sea ice, Greenland, biological systems, human displacement, or other things that people are interested in into a single “threshold” number is a bit of a strange concept to me. Hansen has an interesting paper on dangerous-interference, but at some point the terminology is subjective, and people need to focus on cost-benefit analysis as well as environmental concerns (like species loss) which is not easily quantified in a dollar sign. 2 C may be too high a threshold for practical application, as for instance, sea ice is currently diminishing faster than models show.

    Strictly speaking, a 3 C per 2x CO2 climate sensitivity corresponds to a 1.9 K increase at 450 ppmv if deltaT= [5.35 ln (450/280)]*(0.75 K/W/m**2), but that is also a long-term response. It says nothing about other aerosols or GHGs either which presumably should cause a positive radiative forcing over the coming century.

  3. Mark J. Fiore:

    I am an amateur climate guy who spends about three hours per day for the past 21 years, since 1987, reading all the climate news on the web and in print as I can manage.I’ve posted to RealClimate a few times.I apologize in advance if my posts are often “off thread” or off topic, but it seems that there is latitude on this rule in the blogging sphere.
    So, here goes. First, as always, thanks to the real experts and real expert commentators and bloggers at RealClimate I always learn from them.Second, I want to mention that last year sometime I posted a comment on Realclimate about the danger of the methane at the seabed floors melting and releasing gigatons of methane. Guess what? The methane releasing seastacks are now being observed.They say that if the methane is all released it has the co2 forcing equivalent of all the coal left on earth, and way more than all the current co2 in atmosphere.It will also force a “forcing feedback mechanism” that will further release all the methane from the seabed floor. If these figures are right then “I told you so”.
    Just kidding. I want to know if the experts at RC and the expert commentators who blog on RC know if this figure on seabed methane is accurate, and, if anyone can tell me if all of it will melt, because, if it does, the news stories from last year say we’re in way more trouble than we’ve thought.
    Also, the new story in the news is that the temperature rise is now expected to be 12 degrees farenheight.(sorry I haven’t figured out how to use Celcius scale yet).And the new news story is now a projected 3 feet sea level rise.
    Can anyone out there in the blogosphere tell me if they saw the same methane sea stack article I saw in the newspaper last week, and can anyone out there tell me if the 3 feet sea level rise and 12 degree Farenheight rise is accurate, so that, when the apocalypse comes, I will have managed to spend all my money in my bank accout so as not to lose it when utter and comlete anarchy takes over on planet earth.
    Despite my paltry attempts at humor, I’d really like a response. My e mail is listed below.I’m now very, very, very worried about the seabed methane seastack observations.
    Mark J. Fiore
    45 Villa Terrac
    San Francisco CA 94114

  4. Slioch:

    We used to have a Nature Conservancy Council for Scotland (part of the UK NCC) here as well, with a sound science base and respected record. But alas, it was emasculated and renamed “Scottish Natural Heritage” in the early 1990s by the UK Conservative Government (with whose prime minister, Margaret Thatcher, who came to power in 1979, you will be familiar).

    Scottish Natural Heritage almost never buys land, and doesn’t object to planning applications even for housing estates in the few remnants of ancient (old growth) woodlands that remain in Scotland. Its most recent chairman, Andrew Thin, was formerly chairman of Scotland’s second and largest national park in the Cairngorms. At the first large public meeting after its establishment in 2003, he announced that the three greatest priorities for the Cairngorms National Park were “housing, housing, housing.”

    Sorry to be somewhat parochial, but we are sometimes tempted this side of the Atlantic to imagine that we are ahead of the US in responding to global warming and environmental destruction. Your article indicates that that is not always the case, particularly with respect to the latter.

  5. David B. Benson:

    I think Jim Hansen has overestimated what the climate system is capable of handling in the long term. I say less than 300 ppm CO2e.

  6. Chris Colose:


    Your information is not very good. Methane responses are potentially a large long-term effect and might have minor implications over comingdecades, but the world is not going to end thsi century.

    P.S.– just multiply by (5/9) to go from change in F to change in Celsius. For absolute values (not changes) you also need to add (C to F)or subtract (F to C) 32.

  7. paulina:

    Whether 2 degrees is the increase to avoid is one question and what emissions-associated radiative forcings to avoid in order to do so is another.

    As I understand it, the IPCC takes no position on the former, but if given the 2 degree target, then we need to target 450 CO2-eq.

    While there is no preordained one-to-one correspondence between CO2 concentration and CO2-eq concentration, Table 5.1 in the AR4 suggests that, for the IPCC 2007, given a 2 degree target, the CO2-alone target would be ca 350 ppm (which can be explained by the IPCC-relevant scenarios not having forcings from non-CO2 emissions continue to cancel each other).

    Is this reading correct?

    If, additionally, Hansen’s analysis shows that we actually need to target 350 CO2-eq, and we, with the IPCC, assume (if those scenarios can be called assumptions) that non-CO2-emissions forcings will not continue to cancel each other, then CO2-alone targets (whether rhetorical or not) need to be well below 350 ppm.


  8. Milan:

    You cannot produce a temperature or concentration target using science alone. You need to use science to generate the best possible predictions of the effects of different levels of temperature range, as well as the likelihood of reaching and particular level of change on the basis of any concentration. You then need to make an ethical and economic decision about how much damage you are willing to accept, as well as how much caution you should employ in the face of risk and uncertainty.

    That being said, scientists could definitely do some very useful work in clarifying the issue of choosing a stabilization pathway.

    [Response:Well said. I agree! The point is without more clarity from scientists, it is hard to do the risk assessments. Of course there *are* several papers available that attempt to provide such clarify, but there is no authoritative document.–eric

  9. Joseph O'Sullivan:

    I had a coworker who spent a summer internship doing legal work a few years back for the Nature Conservancy and she mentioned NC’s plans to do more policy work. I guess she was talking about things like this.
    With NC’s prestige and body of scientific knowledge they could make some valuable contributions.

    The Nature Conservancy has property all over the US which are great places. I would encourage people to find nearby Nature Conservancy properties and visit.

  10. Phillip Shaw:

    This is a great post. I’ve been a member of the Nature Conservancy for years and have supported their goals as well as I can with my limited resources. Eric – thank you for sharing your expertise with them. All of the RealClimate folks should be proud that it has become a benchmark for quality science blogging.

    One question . . . if the goal is 450 ppm CO2 eq, where are we today? I know that we are currently about 385 ppm CO2 but I don’t know the delta for the other GHGs.

    Thanks, Phillip

    [Response: Because of aerosols, for which the forcing is negative, we are actually at about the same CO2 ppm as we are at CO2eq. See our post on CO2e.-eric]

  11. Andrew:


    I thought methane effects were more short-term than long-term. Does not methane dissipate from the atmosphere 5-10X faster than CO2? I thought methane lingered for approximately 10 years rather than CO2’s 100 years? I realize all these numbers are inexact, but they do indicate some approximation. Why then would methane’s effects be longer-term as you indicated, rather than shorter-term?


  12. pete best:

    I thought it was all abnout the charney limit, 550 ppmv for a 3C rise (most likely) but then James Hansen comes along and talks about Earth sensitivity (real climates term in their recent post on the subject) being over many decades or even a century or two being double this limit. Hence 450 ppmv of CO2e might destroy more than we care to admit or presently know.

  13. David B. Benson:

    Phillip Shaw (10) — My amateur understanding is that it just happens to be the case that all the other forcings approximately balance out so that 385 ppm CO2 ~ 385 CO2e.

  14. Jim Eager:

    Andrew @11, but over that 10 years methane is many times more potent than CO2. And remember what methane breaks down into, namely CO2 and H2O, so it’s carbon stays in the atmosphere.

  15. David B. Benson:

    What happens with 2 K warming? Here is a review of Mark Lynas’s “Six Degrees” which summarizes his studies:

    What will climate change do to our planet?:

  16. Chris McGrath:

    Phillip Shaw (#10),

    The IPCC summarised the combined radiative forcing of CO2, other long-lived greenhouse gases, aerosols, and landuse changes as follows:

    “Atmospheric CO2 concentrations [reached] 379 ppm in 2005 … The direct effect of all the long-lived GHGs is substantial, with the total CO2 equivalent concentration of these gases [in 2005] estimated to be around 455 ppm CO2-eq (range: 433-477 ppm CO2-eq). The effects of aerosols and landuse changes reduce radiative forcing so that the net forcing of human activities is in the range of 311 to 435 ppm CO2-eq, with a central estimate of about 375 ppm CO2-eq.”

    See the IPCC (2007) Working Group III report at page 102, available at

  17. Chris McGrath:

    The question of what levels of greenhouse gases constitute “dangerous climate change” seems to cry out for a full post from RealClimate, rather than being treated as merely an aside here.

    The policy objective of avoiding “dangerous climate change” comes from Article 2 of the United Nations Framework Convention on Climate Change 1992 (UNFCCC), which states three qualitative criteria for what this means:

    “The ultimate objective … is to achieve … stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.”

    Considering current levels of greenhouse gases appear likely to completely alter the Arctic sea ice, it seems obvious that we have passed the threshold of radiative forcing sufficient to cause of “dangerous climate change.”

    Considering one of the world’s most sensitive ecosystems, coral reefs, stabilising greenhouse gases and aerosols around 350 ppm CO2-eq and allowing a rise in mean global temperature of 1°C appear to be the highest targets that should be set if coral reefs are to be protected from serious degradation.

    There is a discussion of the policy objectives necessary to protect Australia’s Great Barrier Reef at

    The 450 ppm CO2-eq / 2°C targets will lead to dangerous climate change. The decision by the EU and many conservation groups to focus on them is driven not by the science or close adherence to the criteria in Article 2 of the UNFCCC, but pessimistic assumptions on what is practicable and politically feasible to achieve in the real world.

  18. Marcus:

    Andrew @11: What Chris (@6) was talking about was not methane emissions, but rather methane feedbacks: eg, methane clathrates and permafrost releases. And I think he is right that researchers in the field, despite some recent results, mainly believe that these positive feedbacks will be small in comparison to anthropogenic emissions this century. Next century, all bets may be off (there’s a LOT of carbon locked up in the permafrost).

    Philip Shaw @10: Depends on what calculation you do. claims 422 CO2e using CO2 + CH4 + N2O (I calculate 430 for that same combination). One could argue we’re at 458 CO2e using the basket of 6 Kyoto gases and the Montreal gases. Or one could, as I presume David Benson (@13) has done, take the net anthropogenic forcing of about 1.6 W/m2, in which case, yes, we’d be at about 385 CO2e. Of course, if you believe that we _will_ clean up SO2 + BC + the other tailpipe emissions in the near future (none of which are stock pollutants), then we’re closer to the higher numbers than the lower numbers…

  19. Marcus:

    On targets: It has been my personal opinion for a while that all this talk of long term targets and Kyoto caps and stabilization pathways has been an unfortunate distraction from what we _should_ have done (and perhaps should still do, though we’ve lost a decade, unfortunately).

    Namely, if I were to write up a list of attributes of the ideal climate policy that Congress would pass next session it would include this:
    a) A low carbon price – either a tax, or a cap-and-trade with a low safety valve.
    b) A clear progression of upward costs of either the tax or the safety valve (5% a year or so)
    c) A clear mechanism by which, as the science and economics and international situation inform, Congress can adjust the rate up or down as needed.
    d) Appropriate mechanisms to balance the regressive nature of higher energy prices, and to compensate those states/industries most badly damaged WITHOUT subsidizing their continued existence.
    e) Incentives/tariffs/bilateral or multilateral agreements/GEF funding/whatever to encourage other international actors to follow suit in an appropriate (but not necessarily identical) way.
    f) A few additional policies to deal with areas in which the incentives don’t work right (eg, tenant/landlord issues, energy research and public transit subsidies, standards to deal with less-well characterized sources that may not work so well under economic instruments such as agricultural methane, N2O, or BC, and public information campaigns).

    My reasoning is thus: We aren’t yet near the point at which we can really define what “Dangerous Anthropogenic Interference” with the Climate System might be in terms of temperature. We aren’t yet near the point where we can determine a temperature from concentration without large uncertainty. We aren’t at the point where we can make good estimates of costs of meeting emissions targets. We _DO_ know, however, that climate change is likely to be a problem, that we should start earlier rather than later, that a price signal will stimulate conservation and energy technology investment and deployment, etc.

    My speech to green groups would be: You always claim that reducing carbon emissions will be cheap. So, we shouldn’t need a large price. And isn’t a small price now better than no price? Also, you believe that climate change signals will become clearer every year. So put a little trust in our future Congresses to recognize that and increase the prices appropriately.

    My speech to industry would be: take a low, certain price now and a fairly clear path forward rather than an uncertain price (possibly large, possibly zero) in the future. Every industry person I talk to claims they hate policy uncertainty. And if you are a climate skeptic, you believe that the lack of warming should eventually become clear. So put a little trust in our future Congresses to recognize that and decrease the prices appropriately.

    But I realize I’m politically naive, and my approach would never work. Alas.

  20. Nigel Williams:

    Surely there are sufficient indications that we are already at a tipping point for dear Gia. Ignoring mans own efforts today’s climate is giving us melting glaciers, melting ice sheets, advancing desertification, rotting tundra, increased storm intensities and now dismantling calthrates.

    No point fretting about what doubling CO2 will do, or about ‘sensitivities’. We know enough to know that the time to do a U-turn is NOW! Every step forward in the business-as-usual (or worse the business-as-likely) direction merely takes us deeper down a black hole of our own creation.

    We know we have a car wreck – telling us the tail light is broken too is kinda surplus information!

  21. Marcus:

    Finally: thanks for an interesting post. I approve of Nature Conservancy’s tactics, and would love to see their reasoning and science posted in a clear blog fashion paralleling that of realclimate.

    I was impressed with this USA Today article about the Nature Conservancy and their thinking about protecting ecosystems in the face of climate change:

  22. Rod B:

    Eric, a sandbox-I question if I may. I’m not familiar with the term 450ppm “CO2 radiative equivalent.” My gut guess is that it is a concentration of all greenhouse gases normalized to CO2 concentration. Is this correct? If so what ballpark concentration would CO2 be with 450ppm CO2 radiative equivalent?

  23. Arch Stanton:

    Phillip (10),


  24. Karen Street:

    I understand it somewhat differently.

    If the GHG concentration reaches 450 ppm and stays there for a while (path matters: how long we take to get there, how long we stay there, how rapidly we reduce afterwards), there is a 50% chance that the temperature increase this century will be less than 2.0°C, and 50% that it will be larger. There is a 90% probability that the increase will be between 1°C and 3.8°C. The 5% tails go to 0.8°C and up to 5°C or warmer.

    So stabilizing at 450 ppm CO2e doesn’t guarantee that the temperature increase will stay below 2°C.

    It’s worth pointing out that International Energy Agency’s Energy Technology Perspectives ( describes the path to a median probability of a 2.4°C increase as difficult, eg, requiring unprecedented levels of cooperation. Also, the current rate of increase in GHG emissions is faster than the fossil intensive scenario in IPCC (well, it was up until very recently).

    If we want a greater than 50% chance of a 2°C cap, we need to reduce GHG emissions even faster than the ambitious and possibly expensive proposal from IEA.

    I support rapid reductions. I’m for paying what it costs, and finding ways to limit our choices, so flying and driving and etc become less attractive choices. I just raise this issue because discussions of a 2°C cap occur in the public, but I am not seeing such discussions from groups like IEA.

  25. Lynn Vincentnathan:

    Re #11 and 14, I think the real danger is the speed with which the methane hydrates and permafrost melt. If enough methane is put into the atmosphere within a 10 year frame, that could really compound and add up to a lot of warming, & also speed up the melting of the rest of the frozen methane emissions even faster.

    It seems to me that this human-induced warming episode is a much faster warming than any episode in the past.

  26. Chris Colose:

    Hi Andrew,

    I actually wasn’t referring to the atmospheric residence time of the gas (which is about 10-12 years), but rather the transition timescale for a tipping point of mass release of methane from seafloor hydrates (which Lenton et al 2008 put on the order of 100 to 100,000 years). Permafrost release (as opposed to methane on the seabed) of CO2 and CH4 is a gradual thing over this century, and that will probably be non-trivial but not the doomsday scenario as portrayed in comment #3.

  27. Asteroid Miner:

    “its method of protecting land: buying it. Neither free-market boosters (if there are there any remaining) nor lefty environmentalists have any trouble with this.”
    Wrong. It is a class warfare issue. The Nature Conservancy is denying habitat for humanity. Housing for humans IS an issue. Poor people, and that includes new graduates with jobs, are made homeless or inadequately housed by the Nature Conservancy. Nobody has the foresight to build cities on the badlands so that housing can be built in a place where the Nature Conservancy isn’t interested. Then again, there is no place where the Nature Conservancy isn’t interested. Nobody has the foresight to create factories and jobs in the badlands. Nobody is doing planning at that level. The Nature Conservancy would find some reason why we shouldn’t build houses in a lifeless place, like on the moon. The Nature Conservancy is just a means of excluding everybody who earns less than some threshold, like $250,000/year, and a means of raising the price of land so that the wealthy can increase their profits.

    Cities are built upside down: The buildings are where the parks should be and the parks are where the buildings should be. Look at San Jose, CA or Vancouver or Anchorage. The city is next to the sea level and the mountain tops are uninhabited. The cities should be on the mountain tops where sea level rise will not affect them. History has put cities in the farmland. The cities should be at higher altitude where the soil is untillable, but where we live is dictated by history and the Nature Conservancy.

    Global warming makes the Nature Conservancy’s efforts useless anyway. Polar bears, for example, should be counted as extinct already because global warming will surely make them extinct. For every one species the Nature Conservancy and the Endangered Species Act saves, a thousand go extinct because of global warming. The Nature Conservancy is the epitome of impracticality. The Nature Conservancy will die when Homo Sapiens goes extinct in a century or 2. The Nature Conservancy may as well not exist now. It should be disbanded or re-organized to concentrate its efforts exclusively on global warming. The Nature Conservancy should sell all the land it owns now and buy up coal mines to prevent the mining of coal because burning coal to make electricity is the thing that will make Homo Sapiens extinct.

    I have also heard about methane escaping from the Arctic ocean and from melting permafrost. I saw pictures of snow seemingly on fire because of methane escaping from tundra. I didn’t keep the reference, but a NASA or other science web zine seems a likely place to find it. Since this huge positive feedback has begun, I have heard nothing from RealClimate on how this changes everything, or even confirmation or denial from RealClimate. If this positive feedback is unstoppable, the methane alone makes The Nature Conservancy already irrelevant. Natural positive feedbacks already in action mean that the present 380 ppm CO2 is already past the threshold beyond which we humans can control the climate and prevent our own extinction. Yet RealClimate ignores this issue and continues to talk about 450 ppm equivalent or more as the threshold. Why?

  28. Thomas:

    (3,6) I tend more towards Chris’ position here. We need to numerically evaluate the expected rate of any potential Methane release. Presumably methane hydrate decomposition requires the thermal pulse (from a delta T of climate change) to diffuse downwards through water/mud, and in the permafrost case permafrost. Beyond the top couple of meters, isn’t the timescale of thermal diffusion too long for a significant volume of methane hydrates to be involved? (Note this is a question, not an assertion, real data, and real numbers, and some simulation must be performed to make decent predictions). In any case, it is my observation that the number of laymen who are frightened of a runaway methane-hydrate release triggered by climate change is not a trivial number. Perhaps RC should do a post on what is known about this subject. Otherwise the considerable angst generated by the information vacuum will persist.

  29. don:

    I wouldn’t worry to much about methane, it’s been warmer during previous interglacials and the polar bears did just fine.

  30. Hank Roberts:

    Published: October 18, 2008

    WASHINGTON (AP) — The Interior Department has advanced a proposal that would ease restrictions on dumping mountaintop mining waste near rivers and streams, modifying protections that have been in place, though often circumvented, for a quarter-century.

    The department’s Office of Surface Mining issued a final environmental analysis Friday on the proposed rule change, which has been under consideration for four years. It has been a priority of the surface mining industry.

    30 days to comment.

  31. GlenFergus:

    Maybe a pendant on the CO2E thing ought ot notice another little AGW misaprehension which is repeated here, vis, “ecosystem change with … changes in precipitation”. What matters to tallgrass prairie, as to vegetation everywhere away from the wettest regions, is soil moisture – not precipitation.

    Specifically, it is the depth, duration and frequency of soil moisture deficit which tends to determine vegetation communities. And as climate scientists well know, soil moisture is a complex temporal function of both precipitation and evapotranspiration. AGW may well decrease the former in the midwest (or markedly alter its temporal distribution), but it is virtually certain to increase the latter. As a first approximation, potential evapotranspiration is a direct function of mean temperature. In Australia, we’re realising that changes on both sides of the soil moisture equation are important to increasing aridity.

    [Response: A very good point. Of course the Nature Conservancy folks know this too; I was just giving an example of the kind of thing they need to think about, that motivates their concern about climate change. But my example would have been better had I simply said soil moisture, as you point out. Thanks for adding that.–eric]

  32. Chris Colose:

    don (29),

    I’ve seen this argument used by Bob Carter. From what I understand, polar bears as we know it evolved after 120kya so no previous interglacial would really provide a decent analog to a continued rise in CO2 over this century. Didn’t Cecilia Bitz and others project a seasonally free arctic sea ice at 2040? Again, no biologist, but everything I read shows that polar bears depend heavily on year-round ice. And the arctic ecosystem is changing on many levels– not just the polar bear


  33. TomRooney:

    #29. Molecular clock data show a rather messy and very rapid speciation event for polar bears, and I am not sure they were around (or that they persisted) during the Pleistocene interglacials. You may be correct, but you certainly do not make a strong argument.

  34. TomRooney:

    #29. The polar bear represents a recent speciation event, and the extant lineage may not have existed during prior to the final glacial event during the Pleistocene.

  35. John C:

    Not sure if this is a relevant post for this question ….. can anyone tell me how much of the T rise between an ice age and an interglacial period is due to the CO2 forcing alone (ie. without other feedbacks – which were happening anyway). How much global T rise does an increase in CO2 from 180ppm to 280ppm give ? On its own. All I have is the commonly quoted number of 1 degree F for every doubling of CO2 (without additional feedbacks). So the 180 to 280 ppm CO2 increase should contribute about half a degree F ? Give or take – is this roughly correct ?

  36. John Wilson:

    Clearly, the 2°C/450 ppm numbers have completely permeated the policy-advocacy realm. Yet while they are arguably derivable from the IPCC reports, it is actually not clear to what extent the larger scientific community really believes these are the right numbers. There simply has not been a process to evaluate this that compares in depth and breadth with the IPCC. A new and much more comprehensive analysis, by a much greater group of scientists, would be valuable at this juncture.

    YES! The IPCC has previously convened special workgroups to tackle important issues. This is strongly needed, there is much confusion out there on what the IPCC has and has not said.

  37. SecularAnimist:

    Asteroid Miner wrote: “Poor people, and that includes new graduates with jobs, are made homeless or inadequately housed by the Nature Conservancy.”

    What in the world are you talking about? Got specifics? Evidence? Anything?

  38. Guy:

    I’m glad the subject of targets has been raised again (having gone on about it for months I would say that, I suppose!) Eric’s call for a new scientific analysis is welcome, but how can this be arranged with all due haste? Copenhagen 2009 is now only 14 months away, and I guess the community can’t just dump it on their conference on day one. But they do need more to go on – as many here have said, there is literally a world of difference between a very hard 450ppm target that won’t do what is required, and a very very very hard 350ppm target that hopefully will.

    This question – surely – is the most pressing that Real Climate can engage in.

  39. Jim Eager:

    Re don @29: “I wouldn’t worry to much about methane, it’s been warmer during previous interglacials and the polar bears did just fine.”

    But how did our agriculture, coastal cities, ports, refineries and other infrastructure do during previous interglacials?

    Oh, right, there weren’t any.

  40. Jim Galasyn:

    Last year, I delivered my State of the Oceans presentation to the Nature Conservancy branch in Seattle. They showed me one of their planning maps for the Puget Sound, and I was very impressed. They have a sophisticated rugosity model, and the use this to plan their habitat buys. Made me want to do computer modeling for them!

  41. Jim Galasyn:

    Don, the polar bear species is, at most, 200,000 years old, which means it has seen only one interglacial. Like humans.

  42. Chris Colose:

    After comment #10 and the response, I should retract my comment in post #2 on “It says nothing about other aerosols or GHGs either which presumably should cause a positive radiative forcing over the coming century.” I was not thinking of the equivalent– live and learn.

  43. David B. Benson:

    Chris Colose (32) — According to Wikipedia

    According to both fossil and DNA evidence, the polar bear diverged from the brown bear, Ursus arctos, roughly 200,000 years ago.

    which implies polar bears survived

    “Less Ice In Arctic Ocean 6000-7000 Years Ago”:

    and presumably even less during the Eemian interglacial.

    [Response: Guys, I’m not claiming expertise on polar bears, which I don’t have. But the comparison with the last interglacial, and the Eemian, is not necessarily at all relevant. In neither of these past times did it get warm as fast as is happening now. Rates matter, usually more than magnitudes. In any event, we may well be heading for warmer-than-Eemian in the long term–eric]

  44. Chris Colose:

    David (43), thanks

    I just did a bit of research out of curiosity. I’m not well read in polar bear evolution here, but I think whoever wrote the wiki article misread the reference. Reference 14 in the wiki article says, “polar bears are thought to have originated from a segment of the Siberian populations of brown bears (Ursus arctos) which was isolated during the glacial advanced of the mid-pleistocene.”

    A more thorough and recent document says, “It has been proposed that polar bears are believed to have originated from a group of grizzly bears (Ursus arctos) which became isolated during the glacial periods of the mid-Pleistocene approximately 200,000 – 250,000 years
    ago (Talbot and Shields 1996b).”

    and also,

    “Based on the relatively few specimens of polar bears in the fossil history Kurten (1964) estimated that polar bears may have evolved as recently as 70,000 to 100,000 years ago….Age models based on molecular studies of evolutionary relationships among extant species of bears differ considerably as to the divergence time of polar bears from grizzly bears. Wayne et al. (1991) suggested this happened 70,000 – 100,000 yrs ago while Yu et al. (2004) concluded this might have happened 100,000 – 150,000 yrs ago.”

    I read this as geographic isolation began ~200 kya and actual “polar bears” evolved ~100 kya, presumably there would be quite a long time for speciation to occur. I don’t really know how significant the distinction is when it comes to the dependance on sea ice, but the report also divides polar bears into 19 populations, which would be different back in the last interglacial. I suppose various populations would be effected differently by sea-ice losses, depending on nearby landmass.

    The main point is I still doubt the last interglacial is an appropriate paleoclimate-paleobiological proxy for how modern polar bears will fare, especially as we approach later in the century. I don’t doubt that there was less sea ice in the mid-Holocene a few thousand years ago because of more summer sunshine (how do you get a good sea ice extent proxy though?), but we don’t know how polar bears were effected or adapted back then.

  45. Sekerob:

    Well, one magnificent difference… There were no ~6.74 billion homo sapiens sapiens to encroach on their habitat and areas of retreat, nor were any other Arctic regulars under threat that the PB was living off. Any recent counts on Bow heads e.g.

    Was 6-7 thousand years ago not a period when the last mammoths died out? Was 6-7 thousand years ago, half way from the last main glacial period, the climate fully stabilized? Was it then not when the Oceans rose or finished their rise to cause for instance the Black Sea to go from sweet to salt? Then is not now me thinketh.

  46. Sekerob:

    Bow heads live of what? The PB did not live specifically of Bow heads of course. Will there this time around develop dead-zones in the Arctic Ocean due men’s contribution to the water quality?

  47. Ed:

    Regarding polar bears, when the earth warms they will evolve very rapidly into another new subspecies of brown bear that will survive on the diet available to them at that time. They’ll have do less swimming amongst the ice for fish and will spend more time digging for grubs. The ones that don’t adapt… well that’s evolution!

  48. Dill Weed:

    He’s back….

    An open letter from The Viscount Monckton of Brenchley to Senator John McCain about Climate Science and Policy

    Too bad he’s courting the wrong candidate

  49. Barton Paul Levenson:

    John C writes:

    How much global T rise does an increase in CO2 from 180ppm to 280ppm give ?

    Myhre et al. 1998 give the radiative forcing equation for CO2 in the 1-1,440 ppmv range as

    RF = 5.35 ln (C / Co)

    where C and Co are final and beginning values in ppmv. 5.35 ln (280 / 180) is about 2.36, so the extra radiative forcing would be 2.36 watts per square meter. With a climate sensitivity of 0.75 K/W/m2 this yields a change in temperature of 1.8 K.

  50. Jason:

    Mark Fiore…(Comment #3)…You are one of my favorite cartoonists of all time.