Climate Feedback

Polar bears disappear

Cross posted from The Great Beyond

Polar_bear_under_water.jpgOn Friday, the US Geological Survey put out a press release about its new findings on polar bears and their future, and the press responded en masse: Google offers hundreds of stories filed over the weekend. The reports’ conclusion (AP | New York Times) is that diminishing sea ice is a serious problem for the bears, with two thirds of them at risk over the next fifty years – maybe more if, as the report recognises, current estimates of ice loss are too conservative. Most quoted quote: “As the sea ice goes, so goes the polar bear” — Steven Amstrup, the lead author of the new studies.

Some bear populations, such as those of Alaska, are expected to die out completely, which is naturally enough the lead in the Anchorage Daily News. If you’re a polar bear, the place you want to be is what the USGS calls the “convergent ice ecoregion” (a term that doesn’t seem to turn up in the news); this is where the currents pile up ice that can persist for years on the northern shores of the Canadian islands and down the eastern side of Greenland. You don’t want to be west of Greenland or in Baffin Bay, where the ice is seasonal ice and likely to vanish, or on the north shores of Russia and Alaska, where the currents move what ice there is away from the shore (the “divergent ice ecoregion”). Polar_bear_range_map.png

The reports are part of the process by which the US government will decide whether to put polar bears on the endangered species list (earlier Nature story). Geoffrey Lean, at the Independent, pulls the USGS report together with his paper’s investigation into polar bear hunting, which is apparently on the increase. Lean and others also bring up a meeting of religious, scientific and political leaders that’s been going on in Ilulissat , where “leaders of Christian, Shia, Sunni, Hindu, Shinto, Buddhist and Jewish religions took a boat to the tongue of the glacier for a silent prayer for the planet” while Robert Correll, chairman of the Arctic Climate Impact Assessment, warned of “a massive acceleration of the speed with which these glaciers are moving into the sea,” according to Paul Brown in the Guardian.

Meanwhile, almost all of the stories also mention the current reduced area of Arctic sea ice, which this year has already reached a record low and is expected to keep shrinking for a week or so more. The US National Snow and Ice Data Center is keeping a close eye on the situation with regular updates and a lot of interesting data, not to mention a really nice animation that shows how the ice cover evolves over many years (found via and easily seen at Steinn Sigurdsson’s Dynamics of Cats) which explains more about the convergent and divergent ecoregions than a static map ever could.

Images: Grzegorz Polak, distributed under Creative Commons license; Wikimedia

Comments

  1. Report this comment

    Willis Eschenbach said:

    The USGS Study cited above says “Future reduction of sea ice in the Arctic could result in a loss of 2/3 of the world’s polar bear population within 50 years according to a series of studies released today by the U.S. Geological Survey.”

    On the other hand, a variety of references indicate that the Arctic Ocean was ice-free in the summer during various parts of the Holocene, and that the Holocene Thermal Maximum in the Western Arctic was warmer than the present by 1° – 2°.

    The USGS projections seem wildly pessimistic, given the fact that the Polar Bears have obviously survived warmer and more ice-free periods in the past.

    w.

    REFERENCES:

    Kaufman, D.S., et al., 2004. Holocene thermal maximum in the western Arctic (0-180ºW), Quaternary Science Reviews, 23, 529-560.

    MacCracken, M.C., Luther, F.M, (eds), 1985. Projecting the climatic effects of increasing carbon dioxide. DOE/ER-0237, United States Department of Energy, Washington D.C., pp. 381.

    Overland, J.E., and Wood, K., 2003. Accounts from 19th-century Canadian Arctic Explorers’ Logs Reflect Present Climate Conditions, EOS Transactions of the American Geophysical Union, 84.

    Gard, Gunilla, 1993, Late Quaternary coccoliths at the North Pole: Evidence of ice-free conditions and rapid sedimentation in the central Arctic Ocean, Geology, vol. 21, Issue 3, p.227

  2. Report this comment

    Willis Eschenbach said:

    For the views of someone who actually works in the area, see the comments of the Government of Nunavut’s Director of Wildlife Research, Mitchell Taylor, which can be found here.

    A relevant quote from the article about the USGS report:

    “I think it’s naïve and presumptuous,” Taylor said of the report, released by U.S. Geological Survey on Friday, which warns that many of the world’s polar bears will die as sea ice vanishes due to a warming climate.

    “As the sea ice goes, so go the polar bears,” said Steve Amstrup, who led the study.

    But Taylor says that’s not the case. He points to Davis Strait, one of the southern-most roaming grounds of polar bears. According to the USGS, Davis Strait ought to be among the first places where polar bears will starve due to shrinking seasonal sea ice, which scientists say will deprive the bears of a vital platform to hunt seals.

    Yet “Davis Strait is crawling with polar bears,” Taylor said. “It’s not safe to camp there. They’re fat. The mothers have cubs. The cubs are in good shape.”

    Read the article for more.

    All the best,

    w.

  3. Report this comment

    Michael Rhodes said:

    People need to know. Chloroflourocarbon emissions are not tracked, according to the epa response to my query, since use supposed banned. These are generally 3000x more potent heat trappers than co2. Problem is Inhaled general anesthetics are cfcs and n2o, a 600x potent heat trapper. They are blown out of every operating room in the world without mitigation. Unwatched things like these, narrow vested interests against disclosure. We’re toast.

  4. Report this comment

    Willis Eschenbach said:

    Michael, thanks for your post. You seem to be laboring under some misconceptions. Actually, chlorofluorocarbon emissions are tracked. You can find them here.

    In addition, chlorofluorocarbon levels in the atmosphere are tracked, and are available here.

    Regarding the use of CFCs in anaesthesia, this reference says:

    Inhalation anaesthetic agents belong to the partially-

    substituted chloro-fluoro-carbons (CFCs) which have a short

    life time in the atmosphere of only 2 to 6years and which are

    said to have no more than highest 5% of the ozone-damaging

    potency of the fully-substituted CFCs used in industry. The

    annual production of about 5000tons of volatile anaesthetic

    agents represents only about 1% in quantity of the annual

    production of fully-substituted CFCs.

    Finally, N2O is also tracked, data is available here

    While these gases may or may not be dangerous in the atmosphere, the idea that we don’t monitor them either in or out of the operating room because of some kind of conspiracy is simply not true.

    All the best,

    w.

  5. Report this comment

    Swati Singh said:

    Polar bears should be put under endangered list, as their number is less and they are endemic to polar regions. Now with the anthropogenic climate change and resultant melting of polar ice sheet, we are degrading the natural habitat of the polar bear.

    Thus we should take up steps to protect this specie. Also Polar bear is a charasmatic species so if funding can be raised for these, along with them many other species of the habitat, like fishes etc. could be protected as well.

    So without wasting any time further, we should try to protect these charasmatic species, The Polar Bear.

  6. Report this comment

    Willis Eschenbach said:

    Swati, thank you for your contribution. Unfortunately, your facts are incorrect. Polar bears are not decreasing in numbers. Nor are they threatened by warming — the Arctic has been ice-free several times in the last 10,000 years, and the bears survived quite well. Please read the citations I posted above, which confirm these facts.

    There is a fairly long list of species on the planet which actually are threatened, and it is very important that we do what we can to save them. But polar bears, despite being charismatic, are not on that list.

    Best regards,

    w.

  7. Report this comment

    SteveSadlov said:

    Here is the good and sad news story to go with this. The good news is that polar bears are highly adaptable. The sad news is that, like all other bears, polar bears are highly adaptable. The predictable and truly sad spiral of bear – human interaction, which, for bears who are no longer living in undisturbed wild fashion, is a given, is of course seen as well in the case of polar bears. No matter what has happened and will happen with the sea ice, the facts regarding the presence of human development in the polar bear range are what they are. The inevitable has been happening ever since then, and, will continue. It is a sort of late Holocene parasitic relationship. I make no value judgment about this. I simply report.

  8. Report this comment

    Peter J. said:

    Whenever overly aggressive style crops up, a good practice is to check the references. Time consuming as it is…

    Kaufman et al states that the HTM was 1.6 (+/- 0.8) deg warmer than today. He also explains that the Arctic Ocean was quite different as the sea level was substantially lower than today, resulting in a shift of appr. 700 km of the shorelines. Low sea level in turn was due to the extensive ice volume in the Greenland and Laurentian glaciers, the Laurentian disappearing only thousands of years after the maximum. HTM was for that reason a phased affair, lasting several thousands of years, different parts of the Arctic experiencing their maximums at different times.

    I can not find any statement concerning a totally ice free Arctic Ocean.

  9. Report this comment

    Maurizio Morabito said:

    I have to protest against the highly-misleading title of this blog. Polar bears may be “going to disappear” but there is absolutely no indication that they are disappearing in the present tense as indicated by the title

  10. Report this comment

    SMJ said:

    Re: Willis Eschenbach’s post of September 18

    Some other points from Taylor in the cited article found at: http://www.nunatsiaq.com/archives/2007/709/70914/news/nunavut/70914_498.html that I thought interesting.

    While he [taylor quoted by the reporter] agrees that seals are essential food for bears as they fatten up during the spring and summer months – seal blubber makes up half of the bears’ energy intake – he also suspects bears will be able to supplement their diet with other foods, such as walrus.

    Taylor goes on to list other possible terrestrial food sources and hunting techniques not requiring sea ice, but I’m not convinced that they would make up that 50 % energy intake. He thinks that bears may adapt to floating in the water, decoying seals into thinking the bear is a chunk of ice for instance.

    The Walrus probably is capable of surviving the pack ice’s demise, but the current Atlantic population has never apparently recovered from hunting. A quick look at one source lists the Davis Straight walrus population at a few hundred. That same brief search indicated that injured or juvenile walrus are the only ones the bears are likely to be able to pray upon.

    He also questions the claim that the papers used to support the position of the USGS on polar bears have been peer reviewed. “The first time I saw them was when I downloaded them today,” he said.

    Taylor made a 12 point response to the original petition to list the bears as Threatened under the Endangered Species Act. (It’s summarized by the US fish and wildlife Service at paragraph 8) here: http://alaska.fws.gov/fisheries/mmm/polarbear/pdf/Summary%20of%20Comments%20from%20the%20Public_90_Day_Finding.pdf). For someone nostril deep in the issue, to be associated with the lack of peer review claim is specious. Does he have to download everything before it passes muster?

    He’s had a lot of play on the heartland, etc web sites.

  11. Report this comment

    Willis Eschenbach said:

    SMJ, thanks for your post. Unfortunately, the link in your last paragraph doesn’t work. Perhaps you could re-post it?

    Thanks,

    w.

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