Dr. Susan Crockford
Listed below are the info you could put into context the declare that the estimated 234 polar bears not too long ago found in SE Greenland have been dwelling ‘with out sea ice‘.
The distinctive genetic isolation of this new subpopulation makes it one of the fascinating discoveries about polar bears we’ve seen in a long time, but the media have been primed by a press launch loaded with dooms-day local weather rhetoric to focus completely on the model-predicted precarious way forward for the species, like this gem from the lead creator:
“In a way, these bears present a glimpse into how Greenland’s bears could fare beneath future local weather eventualities,” Laidre stated. “The ocean ice situations in Southeast Greenland at this time resemble what’s predicted for Northeast Greenland by late this century.”
As a consequence, the media have been making an attempt to out-do one another with essentially the most over-the-top local weather disaster headlines, see right here and right here. The authors of paper itself and a companion piece do the identical: as an alternative of specializing in the thrilling scientific implications of the genetically remoted inhabitants they found, they promote the most well-liked narrative that polar bears have a bleak future and lecture the general public (but once more) in regards to the want for limiting CO2 emissions (Laidre et al. 2022; Peacock 2022).
PERTINENT FACTS
Is that this area far south? SE Greenland will not be an especially southern habitat for polar bears: the realm of SE Greenland the place this new subpopulation of polar bears reside spans 64-60 levels N. Being beneath the Arctic Circle, it has daylight all winter lengthy, which has similarities to the realm occupied by polar bears in Davis Strait and in northern Hudson Bay and Foxe Basin (from south of Arviat in western Hudson Bay to Southampton Island (see map beneath). Western and Southern Hudson Bay polar bears have been thriving south of this latitude for hundreds of years.
Has there been an absence of vital sea ice? No. In accordance with the paper, the land-bound quick ice that the majority ringed seals use to provide start and nurse their pups in spring (April-Might) remains to be routinely accessible in SE Greenland. Polar bears want this spring ice as a result of that’s after they feed most closely on new child seals: 2/3 of their yearly consumption is consumed in these months, making spring ice essentially the most vital ice habitat for polar bear survival. In distinction, lead creator Kristin Laidre advised The Guardian [my bold]:
“What we find out about polar bears is that having sea ice for about 100 days a yr is simply method too few for bears to outlive,” she stated.”
Nonetheless, this assertion about realizing polar bears want way over 100 days of sea ice will not be true: it’s a mannequin output based mostly on assumptions, not a reality (Molnár et al. 2010, 2020).
With a couple of exceptions between 2015 and 2019, the fjords utilized by the bears (see map beneath) had substantial spring quick ice. As well as, the authors admit that some bears moved over-land between fjords, generally over lengthy distances (Laidre et al. 2022:1333 and Fig. S4), suggesting to me that if ringed seal pups weren’t accessible some years in one of many three southern-most ‘house fjords’, the bears merely moved to an adjoining one with higher feeding alternatives for a couple of months.
Does summer time looking maintain these bears? The authors assumed that summer time looking of seals from bits of glacier ice has allowed these SE Greenland bears to outlive however in actuality they noticed the bears in March and April solely. Any feedback they’ve made to the media or implied of their paper about intensive looking behaviour throughout the remainder of the yr is conjecture. It might be that bears try to hunt in the course of the summer time and fall from glacier ice however that doesn’t imply they’re routinely profitable or that prey taken at these occasions is vital to their survival.
Included within the Laidre paper are two pictures stated to have been taken in September 2016: certainly one of a bear on a contemporary seal kill and the opposite one proven beneath. The photograph of the seal kill seems to be the one concrete proof the authors have of profitable looking on the glacier ice in summer time. Though most SE Greenland bears most likely take a couple of seals within the glacial ice it might be that they’re extra like Svalbard bears, who don’t spend a lot time looking in fjords in summer time and fall regardless that each ringed seals and bearded seals are current (Hamilton et al. 2017:1060 and 1063).
At difficulty is whether or not or not any seals the bears devour over the summer time and fall signify a considerable portion of their eating regimen. The authors presume they’re however really present no information to help their assumption.
Are these bears thriving? It seems they’re. The pictures supplied by the authors point out that SE Greenland polar bears they encountered have been in wonderful situation, since I count on that if lean or ravenous bears had been seen we might have been proven footage of them. For instance, the photograph beneath supplied within the press launch, taken in March, exhibits a really fats bear on a little bit of glacier ice imbedded in quick ice: it’s as fats because the bear within the photograph taken in September copied above.
Fellow polar bear specialist Andrew Derocher, interviewed by Vox, implied that SE Greenland bears have been ‘not in superb situation‘ and never reproducing nicely. Nonetheless, the information reported within the paper don’t help this view. The authors really say [my bold]:
We discovered no variations in litter sizes between Southeast Greenland and Northeast Greenland subpopulations, which suggests comparable cub survival. Grownup feminine physique mass, an vital determinant of cub manufacturing and survival, was decrease in Southeast Greenland than in a number of different subpopulations however was much like that of Northeast Greenland bears and the Barents Sea subpopulation (fig. S26 and desk S11), each of which use glacial fjords. It’s attainable that low start charges are influenced by extremely fractured fjord and mountain habitats that scale back bear actions and impede breeding pair formation.
Laidre et al. 2022:1334
Are glacier-front habitats uncommon? The summary of the paper states, “…marine-terminating glaciers, though of restricted availability, could function beforehand unrecognized local weather refugia“. Many media shops interpreted this to imply that marine-terminating glaciers with highly-productive waters in fjords are uncommon, see right here and right here. Nonetheless, an estimated 537 marine-terminating glaciers are scattered alongside the coast of Greenland alone (Kochtitzky and Copland 2022; Meire et al. 2017) and polar bears are identified to hunt in these fjords in NE Greenland as they do in SE Greenland (Laidre et al. 2022).
Moreover, one group of researchers estimated there are a complete of 1,704 marine-terminating glaciers within the Northern Hemisphere (Kochtitzky and Copland 2022, see their Fig. 1 beneath) and solely 43 of these are not within the Arctic. Many marine-terminating glaciers additionally exist within the Canadian Arctic on Ellesmere, Devon, and Baffin Islands, the Franz Josef Land archipelago, Novaya Zemlya, and Severnaya Zemlya (in addition to alongside your entire Greenland coast and within the Svalbard archipelago). Because of this substantial glacial ice in coastal fjords, as potential sea ice ‘refugia’ habitat for seals and polar bears in a hotter world, are reasonably widespread and considerable, even when lots of the glaciers are at present retreating a bit (Choi et al. 2021; Cook dinner et al. 2019; Sommer et al. 2022).
How did they get there? I’m actually dissatisfied with the authors’ refusal to handle why the bears received trapped in SE Greenland within the first place. To me, that is essentially the most fascinating scientific query revealed by their analysis.
In my final submit, I provided the speculation that very chilly situations and intensive sea ice within the early 1800s could have created situations conducive to trapping a small variety of bears beneath 64 levels N and maintaining them there for many years (presuming that the authors’ estimate of the timing of this inhabitants spit is correct). It appears to me Laidre and colleagues didn’t need to point out the chance that intensive sea ice only some hundred years in the past might have been the trigger as a result of it might be an admission that sea ice situations can change naturally and dramatically over brief time intervals.
The one info the authors present with regard to historic local weather situations is discovered of their Supplemental Knowledge (pg. 7), the place they point out that climate data on the SE Greenland coast at 65 levels N (Tasiilaq, station 4360, 1895-present) point out the late 1800s had the coldest winters, with hotter winters within the Nineteen Twenties-Nineteen Thirties adopted by cooling, and warming once more starting within the Nineteen Eighties (citing Cappelen 2014).
Seemingly, no analysis effort was expended to analyze why bears received trapped in SE Greenland two centuries in the past and remained remoted ever since: the paper comprises no dialogue of the difficulty and even to the media, they stated primarily, “we do not know“.
Conclusion
It’s clear that these SE Greenland polar bear are not surviving with out sea ice: they’re surviving with out sea ice in the summertime and fall, simply as bears do many areas of the Arctic, together with Western and Southern Hudson Bay. These bears nonetheless have entry to seal pups on the quick ice of the fjords in spring, which is after they really want considerable prey. Actually, I contend this paper offers good further proof that sea ice in early spring, not summer time and fall, is vital to polar bear survival.
There is no such thing as a proof to help the suggestion by Ed Yong at The Atlantic that these SE Greenland bears may very well be “the final polar bears on Earth” (likened to mammoths surviving the Final Glacial Most on Wrangel Island). Apart from the truth that glacier-front habitat like that utilized by ringed seals and polar bears in SE Greenland at this time is considerable all through the Arctic at a lot larger latitudes (and thus sure to outlive a bit extra warming), the Laidre paper offers no proof that these polar bears devour extra seals in summer time and fall than bears do in open sea ice habitats.
Lastly, the failure of the authors to handle essentially the most fascinating scientific query of all is an enormous let-down, particularly since they selected to publish this analysis forward of a inhabitants measurement estimate for East Greenland, which is a long time overdue. They spent loads of effort tying this phenomenon of an remoted subpopulation dwelling amongst melting glaciers to future world warming however seemingly none trying to find why the bears received trapped in SE Greenland within the first place. Have they no scientific curiosity? Or did they push it apart in deference to the world warming narrative as a result of it should at all times take priority? Both possibility is an actual loss for science.
Footnote: The precise inhabitants measurement estimate cited within the opening line of this submit (234, for 2016-2017) is supplied solely within the Supplemental Knowledge (pg. 26): within the paper and press launch, the authors say “a couple of hundred”.
References
Cappelen, J. (Editor) 2014. Greenland – DMI Historic Local weather Knowledge Assortment 1784–2013. Technical Report 14-04, Danish Meteorological Institute. https://www.dmi.dk/fileadmin/user_upload/Rapporter/TR/2014/tr14-04.pdf.
Choi, Y., Morlighem, M., Rignot, E. et al. 2021. Ice dynamics will stay a main driver of Greenland ice sheet mass loss over the following century. Nature Communications Earth & Atmosphere 2: 26. Open entry https://doi.org/10.1038/s43247-021-00092-z
Cook dinner, A.J., Copland, L., Noel, B.P., et al. 2019. Atmospheric forcing of fast marine-terminating glacier retreat within the Canadian Arctic Archipelago. Science Advances 5(3):eaau8507. DOI:10.1126/sciadv.aau8507
Hamilton, C.D., Kovacs, Ok.M., Ims, R.A., Aars, J. and Lydersen, C. 2017. An Arctic predator–prey system in flux: local weather change impacts on coastal house use by polar bears and ringed seals. Journal of Animal Ecology 86:1054–1064.
Kochtitzky, W. and Copland, L. 2022. Retreat of Northern Hemisphere Marine-Terminating Glaciers, 2000–2020. Geophysical Analysis Letters 49(3):e2021GL096501. https://doi.org/10.1029/2021GL096501
Laidre, Ok.L., Supple, M.A., Born, E.W., et al. 2022. Glacial ice helps a definite and undocumented polar bear subpopulation persisting in late twenty first century sea-ice situations. Science 376 (6599): 1333-1338. https://www.science.org/doi/10.1126/science.abq5267
Peacock, E. 2022. A brand new polar bear inhabitants: Can the worldwide conservation settlement shield these bears? Science 376(6599):1267-1268. https://www.science.org/doi/10.1126/science.abq5267
Mauritzen, M., Derocher, A.E. and Wiig, Ø. 2001. House-use methods of feminine polar bears in a dynamic sea ice habitat. Canadian Journal of Zoology 79:1704-1713. http://www.nrcresearchpress.com/doi/abs/10.1139/z01-126#.U0spVlda9lo
Mauritzen, M., Derocher, A.E., Wiig, Ø., Belikov, S.E., Boltunov, A.N., Hansen, E. and Garner, G.W. 2002. Utilizing satellite tv for pc telemetry to outline spatial inhabitants construction in polar bears within the Norwegian and western Russian Arctic. Journal of Utilized Ecology 39:79-90. http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2664.2002.00690.x/summary
Meire, L., Mortensen, J., Meire, P., et al. 2017. Marine-terminating glaciers maintain excessive productiveness in Greenland fjords. International Change Biology 23:5344-5357. Open entry https://doi.org/10.1111/gcb.13801
Molnár, P.Ok., Bitz, C.M., Holland, M.M., Kay, J.E., Penk, S.R. and Amstrup, S.C. 2020. Fasting season size units temporal limits for world polar bear persistence. Nature Local weather Change 10:732-738. https://doi.org/10.1038/s41558-020-0818-9
Molnár, P.Ok., Derocher, A.E., Theimann, G., and Lewis, M.A. 2010. Predicting survival, replica and abundance of polar bears beneath local weather change. Organic Conservation 143:1612-1622. http://www.math.ualberta.ca/~mlewis/Publicationspercent202010/Molnar-Derocher-Thiemann-Lewis.pdf
Sommer, C., Seehaus, T., Glazovsky, A. and Braun, M.H. 2022. Elevated glacier mass loss within the Russian Excessive Arctic (2010–2017). The Cryosphere 16:35-42. https://doi.org/10.5194/tc-16-35-2022
