Charismatic Megafauna

And they don’t come more mega than polar bears. There’s a new report out, ClimateFeedback has blogged it, so I feel duty bound to snark about it.

Skipping rapidly over the press release (note how the “will” of the title is “could” in the text) we come to the reports themselves. And how nice: there is one on model uncertainty. Which even tells you how the models they used were selected: The proposed selection criterion selects models with less than 20% error in their simulations of present-day September sea ice extent. Its probably fair enough, if not very exciting (if you want to feel skeptical look at their fig 9, which is from Stroeve).

But I was more interested in how they match polar bear survival to sea ice. For the southern Beaufort Sea (there seems to be more on this than elsewhere, because this is the US bit?), this turns out to have been done on the basis of capture-recapture studies giving results for “good” ice years 2001-3 and “bad” ice years 2004,5. That doesn’t seem like very many years to me. So clearly they are going to have to treat uncertainty carefully. The abstract sez: Deterministic models yielded estimates of population growth rate lambda under low ICE conditions in 2001-2003, ranging from 1.02 to 1.08. Under high ICE conditions in 2004-2005, estimates of lambda ranged from 0.77 to 0.90. The overall growth rate estimated from a time-invariant model was about 0.997; i.e., a 0.3% decline per year. (nb, ICE in the above is their variable for, confusingly, ice-free days; so high ICE is low ice is bad for bears. nb also ICE is about the ice in the region of the bears, so may bear little relation to overall arctic conditions).

OK, sounds good so far: but then if you look much further down at table 1 you discover that those are just for the estimates by year: eaach of which have substantially higher uncertainties (all of which come from some model which I know nothing of). So the 2001 value, which is 1.059, actually has a 90% confidence range of 0.083 to 1.093. I’m presuming the pop growth has the obvious interpretation: pop(year+1)=pop(year)*lambda, so < 1 means eventual disappearence and > 1 means eventual domination of the earths biomass. 2005 is a bit more constrained at 0.577 to 0.959.

Then the model, of course, assumes that all the variance good-bad is down to ICE. It might be, but with such a small sample of years there could easily be other things going on. So the projection assuming continuing current conditions (-0.3%/y) is so small as to be essentially constant; you need to put in future warming, hence less sea ice, to get declines. They do say The parameter estimates on which the demographic models are based have high levels of uncertainty associated with them but then proceed to wish that away. Another little caveat is that the population dependence on ICE, when projected into the future, goes far outside the range for which the model was calibrated.

There is some about the northern Beaufort Sea too. I was puzzled by the word “Harvest” keeping on popping up, until I realised it meant “killed by people” (there is a bit at the end where they make the astonishing statement “we predict that if… the harvest becomes unsustainable, the population will likely decline”. Only “likely”?). But anyway… sadly that study doesn’t produce comparable population-expansion numbers to try to compare with the previous. This study, despite having a much longer period (1971-2006) can’t such much about sea ice declines impacting the bears because in that region there always is ice, oh dear.

Conclusion: the idea that polar bears might well decline if there is less sea ice seems fairly plausible, but of these two reports one is based on such a small sample of years that it doesn’t really strengthen the “plausible” up very much; and the second doesn’t consider that sort of variation. Exactly where the ice is, is far more important than its overall extent.

[Update: as JOS says in the comments “The lawsuit is part of a bigger campaign to get the government to regulate AGW pollution” and I think thats the bottom line. I don’t like this, and I doubt its a good tactic -W]

Comments

  1. #1 Steve Bloom
    2007/09/10

    I wonder how many models will still make that 20% cut after taking this year into account. None? Maslowski publishes squat, but his informal prediction is looking better all the time.

    [Look at the graphs. You’d have to shift the centre up or down a loooooong way to exclude all models -W]

  2. #2 Alexander Ac
    2007/09/11

    It has to be acknowledged, that the polar bears also survived the interglacials in the pas (which were 2-3C warmer than today) and there was no or little ice on the North Pole. How did they survive??

    [I did wonder about throwing that into the pot but decided not to. I’m not sure they were 2-3 globally – probably only in the poles? It is an argument against getting over excited. Perhaps they migrated S a bit? -W]

    Off-topic

    a funny think: Al Gore vs. Vaclav Klaus…
    http://motls.blogspot.com/2007/09/klaus-vs-gore-newspaper-ads.html

  3. #3 crandles
    2007/09/11

    Don’t understand Williams ‘look at the graphs’ answer. Red actual line is below 12 of 13 models. Cryosphere has over a 25% decline in minimum sea ice area this year; NSIDC has around 20% for ice extent. Reading the text around Williams quote on page 8, they are using over 50% ice cover for ice extent instead of the usual 15%. (I presume this makes sense as they are interested in ice sufficiently thick to support weight of a polar bear.) If you also restrict to the relevant area, you could arrive at a completely different figure. The following might help:

    [Look at fig 12. You’d have to push the obs a lo(oo)ng way down to get to having none of the models within +/- 20% -W]

    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/recent365.anom.region.11.html

    That might suggest a 50% decline of 2007 over 2006.

    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20050910.jpg
    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20060910.jpg
    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20070910.jpg

    Are you still confident that 20% is a ‘loooooong’ way in view of the 2007 ice extent?

    Ten of 13 models passed the 20% test. I would have thought a more interesting test might be on rate of decline. Do all 13 models underestimate the rate of decline? Should and are the models adjusted to reflect the ensemble underestimate of the rate of decline?

    [10 of 13? of 20 -W]

    If lambda is from year to year as you suggest then 0.577 to 0.959 for 2005 looks very scarily low to me. Could lambda be over the average generation rather than year?

    Is that 0.083 meant to be 0.83? If not I don’t know what to make of .083 being lower than .577. If it is .83, 0.577 to 0.959 looks quite different to 0.83 to 1.093.

    [No, its 0.083 -W]

    I agree 2001 to 2005 is not many years and there could be other effects than ice cover. A sensible prior is going to take information about how far bears roam looking for food and the extent to which the ice is used as a base to extend hunting range. With a knowledgable prior, 5 years data does not look likely to be able to firm up the prior much. It might be capable of contradicting reduced ice causes fewer polar bears but it hasn’t. If the data is close to the expectation it might do little to change the prior. William, what do you think should be the reaction/headline to these studies?

    a) Study finds nothing of interest.
    or
    b) Study provide no evidence to contradict view that ice reduction will lower Polar Bear populations and a little evidence to support it.
    or
    c) Shortage of data means we need to complain about needing more studies before reaching any conclusions
    or
    d) The difference between lambda of 0.577 to 0.959 for bad ice years and 0.83 to 1.093 for good years is a sufficiently significant result to say it tends to confirm the view that retreating ice will harm polar bear populations.

    or something else

    [I think I’d go with a merge of all of a-c. And its 0.083 in d (the report is online). I would have liked the reactions to these studies to report what is known about polar bear population changes and what causes them.

    How about thinking another way… why are these studies being publicised? Is it (a) to draw attention to the research so that more will be funded in future? (b) just a helpful newstory to fill out the presses? (c) to help push a green agenda? (d) to provide the public with useful info?

    I know, (d) is wildly over optimistic, but I can’t help hoping -W]
    -W]

  4. #4 crandles
    2007/09/11

    By ‘migrated S a bit’ do you mean stay close to shore? (Water hunting seems important to polar bears.) If the last interglacial was slow to arrive the bears may have leant to stick close to the shore. If we are getting a more rapid disappearance of ice is it less likely they will adapt? I cannot figure out how you would expect a study to tell us the answers to these sorts of questions in advance; the only relevant study being of what happens in the next few years or decades. That doesn’t help the senate make its decisions.

    [Please don’t think I’m tryin g to claim to know much about polar bears. I’m just reading the study. That the bears didn’t disappear during the Eemian is evidence of something. And of course I should have said “N a bit” not “S” – too used to the SH. For all I know, the SB bears disappeared during the Eemian, leaving only the northern most bears (would there be any palaeo evidence one way or another? I wonder). Suppose that happened in 50 years… would that be a porblem?

    As to who gets to make the “endangered” decision – fair enough. Various indigenes have permits to “harvest” bears at the moment, though they don’t use them all up. Presumably endangered status might affect that. What else would it do? -W]

  5. #5 Thomas Palm
    2007/09/11

    Alexander, according to Wikipedia:
    “According to both fossil and DNA evidence, the polar bear diverged from the brown bear roughly 200 thousand years ago; fossils show that between 10 and 20 thousand years ago the polar bear’s molar teeth changed significantly from those of the brown bear”
    It is a young species, and the survival in much warmer conditions is uncertain. OTOH, maybe it is a easy change from a brown bear so that a similar species will appear again if conditions get colder in the far future.

    [Very interesting point, thank you. Via the wiki “some experts disagree” tag I found http://www.ff.org/centers/csspp/pdf/200701_taylor.pdf, which (despite being hosted by ff) seems reasonable. It makes the “eemian” point rather forcefully -W]

  6. #6 crandles
    2007/09/11

    I don’t know much abour bears either. I was looking at figure 9 (as directed?) instead of figure 12. The 13 models came from figure 9 while there are 20 model for figure 12. The abstract indicates it is 20% of present day ice extent. Figure 12 does not appear to cover present day conditions. I don’t have as much time as you to read it all and maybe figure 12 is the relevant figure.

    [Present day is a vague phrase. They mean 1950-95 avg I think -W]

  7. #7 Magnus W
    2007/09/11

    And we (humans) claim big areas of land so moving and adapting for animals this days seams to be quite a different story form the “grate old days”…

    [In general yes. Up in the arctic, perhaps not -W]

  8. #8 Mangus W
    2007/09/11

    Hay! I almost live in the arctic… ;)

    [Lucky you! -W]

    When the (if) ice goes… they better go elsewhere?

    [Depends on whose viewpoint you’re taking. If you’re a polar bear, it would be nice to have somewhere to go where you can live. If you’re… an economist trying to do a cost-benefit analysis of GW, then you need to balance possibly dying polar bears against people emitting CO2. We could, of course, dump them all in zoos. And if it came to it, we probably would, so there is no question of the species dying out (I’m presuming they breed in captivity). Not that that would be quite the same as having them live wild. Perhaps it would be easier to dump food onto them, if they run out of ice to catch seals on. I’m being devils advocate, you understand -W]

  9. #9 James Hrynyshyn
    2007/09/11

    Sorry William, but the case is pretty darn clear. Bears eat mostly seals; seals need ice to bear young; less ice –> fewer seals –> fewer polar bears. It’s that simple.

    [No, its certainly not that simple. It depends a lot on where the ice is. You could lose all the ice in the central arctic and have little effect on the bears. This appears to be why the NB bears aren’t suffering at all, so far -W]

    Thomas is right: polar bears are a very young species, but that’s irrelevant. The bears survive interglacials because so does the ice. Take that ice away and the bears are toast. The evidence from western Hudson Bay, where the bears are doing very poorly, should serve as a window on the future for the other populations.

    [You seem to be missing the point. The bears have survived one interglacial, the eemian. How did they do this, if the T was +2, and if +2 will be a disaster?

    As for WH, try http://www.ff.org/centers/csspp/pdf/200701_taylor.pdf – in fact, if you have any kind of inside perspective, I’d be interested -W]

    I am perplexed by the reluctance of so many observers to pay heed to the rapidly disappearing north polar ice.

  10. #10 Joseph O'Sullivan
    2007/09/11

    The studies are being published and publicized most likely in response to all the attention that the polar bear issue is getting. Even Senators McCain and Lieberman publicly endorsed the lawsuit. When influential senators get involved, agencies notice.

    About the paper on the ff site, the author makes some good points, some bad. First, the Center for Biological Diversity’s petition is a legal document not a scientific paper, so it will by definition be one-sided. Second he states that the petition does not look at the entire population, but under the Endangered Species Act the focus is on the US population, not the global population.

    Third is about the Arctic being ice free during the eemian, I am assuming that this is correct at least for the summers. This brings up a few questions. How many polar bears survived? If a small population survived this would show that the bears barely made it through the eemian. The effects of such a population reduction can sometimes be discovered by using genetic analysis (in cheetahs for example), but I don’t know if this has been done with polar bears. In ecology things are difficult to predict. Just because the bears survived before does not mean they will survive again. For one the ecosystem effects of overfishing and the direct hunting of polar bears obviously were not factors in the eemian. Considering that the eemian was 100k+ years ago the traits that allowed polar bears to survive ice-free conditions may no longer exist. I am also assuming the current rate of climate change is greater than what occurred during the eemian. The faster the change, the less likely a species is to survive.

    Finally, he seems to push the defense of hunting and seems to cast the environmental groups as working for animal rights. In the US there is a difference in what environmental groups and animal-rights groups work for. Most US environmental groups reject much of what animal right groups endorse and reject the extreme tactics they sometimes use. In the political arena some of this confusion is intentionally encouraged and is similar to the way that some accuse research scientists of advancing environmental/leftist political agenda. The goal of the lawsuit is not just to stop the hunting of a cute furry animal.

    The lawsuit is part of a bigger campaign to get the government to regulate AGW pollution. This lawsuit, along with the Center for Biological Diversity’s ESA suit over corals and its lawsuit to get CO2 listed as a pollutant under the Clean Water Act because of acidification, are not being done to get effective action under these laws. In the coral case NOAA states accurately that the US has no system to regulate greenhouse gases. The goal is to get public attention and to force the government to create a framework to address AGW. Lawsuits have been a very valuable tool for environmental groups. The agencies will have to adapt current laws to address AGW, but this will be difficult. Congress seeing this might intervene and will hopefully pass legislation that effectively addresses AGW.

  11. #11 Magnus W
    2007/09/11

    Well since I almost live in the arctic and we don’t have ice all the year and no polar bears live here I think it’s a pretty big chance that they will get extinct if the ice goes… I mean there are rumours about polar bears roaming the streets but that probably where before the Eemain. And I wouldn’t count on the Zoos with all the crazy animal rights groups forming… or… hmm

  12. #12 Hank Roberts
    2007/09/11

    > The bears have survived one interglacial, the eemian.
    > How did they do this, if the T was +2,

    Rate of change, William. Same applies to all species.

    Rapid advancement of spring in the High Arctic.
    Current Biology, Volume 17, Issue 12, Pages R449-R451
    T. Høye, E. Post, H. Meltofte, N. Schmidt, M. Forchhammer
    http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VRT-4P0MSG0-8&_user=10&_coverDate=06%2F19%2F2007&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b3932203d0f828f3e5a9531022e9ac93#

    [Maybe, but then people need to modify their arguments. At the moment the argument is ice-free-summer-arctic => polar-bear-extinction. You’re saying that is wrong – that they can adapt -W]

  13. #13 Bruno
    2007/09/11

    The section of the USGS report on Hudson Bay cites Gagnon & Gough (2005), but does not utilize G&G “East-West Symmetry in Longterm Trends of Landfast Ice Thickness in the Hudson Bay Region, Canada” 32 Climate Research 177-186 (2006). The authors, according to the abstract, analyzed Canadian Ice Service records for 13 stations around HB going back to 1963. “Statistically significant thickening of the ice cover over time was detected on the western side of HB while a slight thinning lacking statistical significance occurred on the eastern side.” The thickening “correlated to earlier freeze-up due to negative temperature trends in autumn.” “The results are in contrast to projections from GCMs and to the reduction in sea-ice extent observed in other regions of the Arctic.”

    An Endangered Species listing for the PB will have no direct effect on Inuit hunting, but will stop Americans from returning with trophies (bear rugs, etc.), and so will make less attractive American sport hunting on Canadian soil. If there are fewer buyers for the excess Inuit hunting “tags,” so the theory goes, fewer polar bears will be killed.

    What the advocates overlook is that by asserting a US governmental interest in protecting the polar bear, the listing would provide Bush with a pretext for invading Canada, protecting from slaughter the helpless bears whose death warrants are signed by the oppressive regime of the Canadian and Nunavut governments.

  14. #14 Juanita
    2007/09/11

    Re. this comment…

    [If you’re… an economist trying to do a cost-benefit analysis of GW, then you need to balance possibly dying polar bears against people emitting CO2. We could, of course, dump them all in zoos. And if it came to it, we probably would, so there is no question of the species dying out (I’m presuming they breed in captivity). Not that that would be quite the same as having them live wild. Perhaps it would be easier to dump food onto them, if they run out of ice to catch seals on. I’m being devils advocate, you understand -W]

    …you may have just been playing devil’s advocate, but the ‘choice’ of dumping a species into a zoo vs. cutting CO2 emissions has probably been a serious thought in some people’s minds. Because bears ARE so charismatic, it’s easy to forget that this story isn’t just about them. The loss of sea ice has the potential to directly affect a wide array of other species, including humans (such as Inuit hunters that still rely on subsistence hunting), multiple seal species, walruses, multiple fish species, and the plankton community that supports the entire marine food chain of the Arctic. Then, there are the indirect effects of the loss of the bears themselves; artic foxes, for example, rely heavily on carrion left by bears (who tend to selectively eat the fat of their prey and leave the rest). And of course, Aboriginal communities–who have precious few economic opportunities as it is–use the bears as food for themselves and their dogs, and can make a living selling pelts and running hunting tours.

    Having said all this, I’m not convinced that extinction of polar bears is a certainty. Furthermore, other threats such as tourism, pollution, loss of denning habitat (yes, even in the Arctic) and other factors may be as important as the loss of sea ice. But even the more conservative estimate of a 30% decline in global bear populations (IUCN/SSC Polar Bear specialist group–http://pbsg.npolar.no/) could have wide reaching impacts in the Arctic. Trying to halt the loss of sea ice is as good a place to start as any.

  15. #15 Dano
    2007/09/11

    What Joseph O’Sullivan said.

    Human impacts on and fragmentation of ecosystems were nearly non-existent in the Eemian, and genetic flow since then makes conditions hard – if not impossible – to compare.

    We can’t unsh*t that big of a bed.

    Best,

    D

  16. #16 Hank Roberts
    2007/09/11

    > You’re saying that is wrong – that they can adapt -W]

    No, I’m saying look at the rate of change — species living adapt (selection pressure works) up to some rate of change, beyond which those plants or animals quit having grandchildren and the population dies out. When change isn’t global, some populations survive.

    The question is whether the rate of change now (what would you say, 100x previous events?) is beyond what natural selection can deal with — whether any species in the food chain that has polar bears as top predator will drop out completely and not be replaced.

    You’re in a position to know a lot more about what’s changing than we are, I know there’s work being done on how the reduction in sea ice changes the algae and plankton that are the primary producers everything else feeds on. I don’t know how much has been finished and published. Anyone at your place have any info to share?

    Losing the top predator can also wreck the food chain below it, that was Aldo Leopold’s insight long ago, and it’s held up as humans have carried out the experiment repeatedly. That’s one reason to worry about ‘charismatic megafauna’ — food chains work both up and down.

    http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1641%2F0006-3568%282005%29055%5B0613%3ALWAPAL%5D2.0.CO%3B2

  17. #17 Eli Rabett
    2007/09/11

    Sorry William, polar bears are plain, outright scary megafauna. If one ever gets you out in the open you are dinner.

  18. #18 Joseph O'Sullivan
    2007/09/12

    Eli Rabett is correct, polar bears in fact are very scary. Polar bear researchers are very, very brave people.

    About 30 years ago in NY City a teenager broke into the Prospect Park Zoo and decided to swim with the polar bears. The police found out and when they arrived they saw the bears eating, really playing tug of war with what was left of the teen. The police reacting in a understandably way shot and killed the bears.

    Polar bears are cute and furry and that is the aspect that gets played up in the media and by environmental groups. In politics image is often more important than reality.

  19. #19 ChrisC
    2007/09/12

    Polar bears are the worlds largest land carnivore.

    Whether or not polar bears are “scary” or “cute” is irrelevant to the discussion about the threats to the species as a result of the loss of sea ice.

  20. #20 Thomas
    2007/09/12

    Without knowing how polar bears survived the Eemian and how similar they even were to the polar bears of today we can’t use that fact to state that they will survive in the future. Not only do polar bears have to cope with extremely rapid climate change, but they have to compete with human hunters, fragmentation of ecosystems, probably more resource extraction in the Arctic as it gets more suitable for humans leading to more pollution etc. Their future look bleak, unless their charismatic nature make us keep them alive through artificial breathing while the ecosystem around them collapses.

    [I’m not saying that proves they *will* survive – its just a piece of evidence suggesting they may. Artificial respiration on polar bears would be very brave indeed :-). From what I can tell from the docs, hunting isnt a major factor any more -W]

  21. #21 crandles
    2007/09/12

    Migrate N a bit looks like a euphemism to me. There is no land north of Alaska. If the route to more northly areas involves going through areas that are already at their polar bear population limit you may really be hinting at US polar bears dying out.

    Is the 2007 ice observations bad news not only for polar bears but also this campaign to get the government to regulate AGW pollution?

    The obs suggest the summer ice will be gone from at least north of Alaska well within 30 years and AGW pollution regulation is not going to make any difference in that timeframe.

  22. #22 SMJ
    2007/09/12

    Re: the habitat implications.

    Brown and Polar Bear produce fertile hybrids and their habitats marginally overlap. In one area where that occurs, North of Alaska’s Brooks Range, the terrestrial Brown (Grizzly) Bears are legally hunted – as they are in almost all areas of the state – but not preferentially, their size being habitat limited. Individual Brownie ranges average 300 sq mi (775 sq km) north of the Brooks. In interior areas to either side of the Alaska Range the extent of ranges varies from 15 to 23 sq mi (39 to 60 sq km), and goes to as low as 1 sq mi (2-3 sq km) in especially favorable costal habitat. The weight of specimens approximately doubles from North to South. The big sothern ones have access to fat and protein from the sea (Salmon).

    The marine adapted Polar Bear is a bit larger than the largest Brownie.

  23. #23 Brian Schmidt
    2007/09/13

    O’Sullivan:

    “under the Endangered Species Act the focus is on the US population, not the global population.”

    He’s right (or right enough for these purposes, anyway). It doesn’t matter for the ESA listing purposes that some bears might survive in Canada or Greenland; it’s enough that the US populations are in danger.

    William:

    “I’m not saying that proves they *will* survive – its just a piece of evidence suggesting they may.”

    The ESA doesn’t require absolute proof of certain extinction in order to apply and require species protection – a credible threat is sufficient, and actually a credible threat to no more than a substantial portion of the species’ range is sufficient. Same holds true about the evidence of a decline – it doesn’t have to be perfect evidence if it demonstrates a credible threat.

    Finally a subject I know something about…

    [I’m not really that interested in the ESA protection, but in whether the bears are actually threatened or not. For that, the Eemian is obviously relevant. It would be interesting to know if any of the pro-there-is-a-problem side address it -W]

  24. #24 Joseph O'Sullivan
    2007/09/13

    This how the CBD handled the Eemian question:

    “Polar bears were well developed as a separate species by the beginning of the Eemian interglacial around 125,000 years ago (Stirling 1998). The oldest known polar bear fossil, collected in London, is less than 100,000 years old (Stirling 1998). Analysis of this fossil indicates that this polar bear, like many other Pleistocene era-species, was significantly larger than the modern animal (Stirling 1998; Amstrup 2003).

    The polar bear may have evolved during the Saalian glaciation when ice covered the Arctic Ocean and seals became a more readily available year-round and particularly rich source of food (Stirling 1998). During the Saalian glaciation, more of the land surface of Europe was covered with ice then ever before, and ice fronts would have separated brown bears, dependent on terrestrial resources, from the bears evolving to exploit the new ice and marine niche (Stirling 1998). Over time, the polar bear expanded its range to its current circumpolar distribution (Stirling 1998). Because the polar bear’s primary habitat is the surface of the sea ice, rather then terrestrial habitat, it is classified as a marine mammal (Amstrup 2003).”
    http://www.biologicaldiversity.org/swcbd/species/polarbear/petition.pdf

    The Fish and Wildlife Service from an earlier report said this:

    “While all bear species have shown adaptability in coping with their surroundings and environment, polar bears are highly specialized for life in the Arctic marine environment. Polar bears exhibit low reproductive rates with long generational spans. These factors make facultative adaptation by polar bears to significantly reduced ice coverage scenarios unlikely. The effects of the Eemian or Sangamon interglacial period (warming period) around 131,000BP on the Arctic marine ecosystem and polar bears are unknown. Due to their long generation time and the current greater speed of global warming, it seems unlikely that polar bear will be able to adapt to the current warming trend in the Arctic. If climatic trends continue polar bears may become extirpated from most of their range within 100 years.”
    http://alaska.fws.gov/fisheries/mmm/polarbear/pdf/Polar_Bear_%20Status_Assessment.pdf

  25. #25 Eli Rabett
    2007/09/13

    The issue of whether polar bears are scary, have you for lunch, megafauna or charismatic is one of framing, of which this thread is a good example. By framing the bears as being charismatic, William is trying to emphasize his view that protecting them is an irrational response to what he sees as a not very great threat of extinction. As usual in these things the real issue is fairly complex brought out in the last few posts. Eli, OTOH, while not sure if they could move on to land, knows that if they had to give up their seal on ice diet they would busy themselves decimating other cute creatures including him. This means, with all the folks moving from Florida to Labrador, the bears would be ruthlessly hunted out.

    [This is getting a bit weird. Bears are clearly charismatic. If you get close to them they are also scary, but few do that. I am *not* asserting that protecting them is irrational, if they are threatened with extinction. I *am* asserting that the evidence that they are threatened is not good so far.

    If they really were threatened, a possible Lomborgian reply is that it wouldn’t take too much to keep them fed with seals brought in for the purpose, were that necessary (and clearly they aren’t going to go extinct, because there are enough in zoos). Yes I know that offends against the purity-of-the-wilderness stuff, but if the goal is not to b*gg*r around with nature then – ta da – you don’t need the bears arguement at all. Just the sea ice melt, or the temperature change, is enough.

    But it isn’t enough, we need the bears too. Which tells you a lot about the real nature of the argument -W]

  26. #26 Chip Knappenberger
    2007/09/13

    You don’t need to go all the way back to the Eemian to find an extended (multi-millennial) period of time when the Arctic was largely warmer than present. The early-to-mid Holocene should suffice. And the polar bears survived then too (obviously). Pages 3-6 of this report have a good description of polar bears and past Arctic climates.

    -Chip

    [Your source is rubbish (though that doesn’t mean its all wrong, of course) but also rather prolix. Where does it give the details of polar bears surving warmth in the holocene? http://en.wikipedia.org/wiki/Image:Holocene_Temperature_Variations.png suggests that holocene temperatures have not been, on average, warmer than now. Which datasets are you thinking of? -W]

  27. #27 Chip Knappenberger
    2007/09/13

    William,

    Page 4 of the report I linked to contains a section on the mid-Holocene warmth (including references to MacDonald (2000) and the IPCC AR4) in the Arctic. As best as I can tell, the wikipedia figure that you pointed to is a global temperature history? Or is it Arctic-specific?

    [The wiki figure contains a pile of different records, as it says. IPCC: thanks. I hadn’t seen that before. Since we’re 0.8 above pre-ind, the orange is “only” +1 over today, so is arguably not so useful for assessing future +3-4 oC type increases. There is a bit of red there, but who knows how extensive? So I think the Eemian is a better “test” -W]

    -Chip

    PS. See here for more global warming/polar bear opinions.

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