Guest essay by Dr. Susan Crockford of Polar Bear Science
Svalbard in the western Barents Sea has recently had less sea ice extent than it had in the 1980s, especially in the west and north, but this is not unprecedented.
New evidence from clams and mussels with temperature-sensitive habitat requirements confirm that warmer temperatures and less sea ice than today existed during the early Holocene period about 10.2ā9.2 thousand years ago and between 8.2 and 6.0 thousand years ago (based on radio carbon dates) around Svalbard. Barents Sea polar bears almost certainly survived those previous low-ice periods, as they are doing today, by staying close to the Franz Josef Land Archipelago in the eastern half of the region where sea ice is more persistent.
As this sea ice chart for 18 April 2018 shows, ice this month has been virtually absent from the west and north coasts of the Svalbard Archipelago, while Franz Josef Land to the east is surrounded by highly concentrated pack and land-fast ice.
From a new paper by Jan Mangerud and John Svendsen (2018) [my bold]:
Svalbard, located between 74Ā° and 81Ā°N, is the warmest place on Earth at this latitude (Drange et al., 2013). This is because of the North Atlantic Current and large-scale atmospheric circulation which transport warm water and air masses from lower latitudes northwards across the Atlantic and along the coast of Norway to Svalbard (Figure 1). Yet, during the Holocene Thermal Maximum, the climate of Svalbard was considerably warmer than at present.
The transition from Younger Dryas cold to Holocene Thermal Maximumwarm conditions took place very rapidly, according to records from nearby Greenland (Taylor et al. 1997), warming in āstepsā of about five years each over a period of about 40 years. This was at last as fast, if not faster than, recent Arctic warming between the 1980s and 2015. And since polar bears of the Barents Sea and adjacent Arctic areas appear to have survived this change to Holocence Thermal Maximumconditions, it challenges the notion that recent warming has been (or will be) too fast to allow polar bears to survive without huge changes in their present distribution (Amstrup et al. 2007).
The summer water temperature map from Mangerud and Svendsen (below) not only illustrates why western Svalbard is subject to periods of no or low sea ice in winter but why Franz Josef Land to the east (surrounded by near-zero temps (in blue), even in summer) is the perfect refugium for polar bears during low-ice years (Aars 2015; Aars et al. 2017; Andersen and Aars 2016; Barr 1985; Chernova et al. 2014; Descamps et al. 2017; Fauchald et al. 2014), see previous post here.
Franz Josef Land provides the most stable sea ice habitat for Barents Sea polar bears because it is largely beyond the influence of warm water influxes from the North Atlantic.
The schematic below from Mangerud and Svendsen shows the warm water incursions from the Atlantic flowing past the west coast of Svalbard at about 11 thousand years ago, when the Laurentide Ice Sheet still covered the eastern half of Canada and the northern US, excluding fish, seals and polar bears from most of Canadian Arctic and Hudson Bay.
Here is the abstract from Mangerud, J. and Svendsen (2018) [my bold, link added]:
āShallow marine molluscs that are today extinct close to Svalbard, because of the cold climate, are found in deposits there dating to the early Holocene. The most warmth-demanding species found, Zirfaea crispata, currently has a northern limit 1000 km farther south,indicating that August temperatures on Svalbard were 6Ā°C warmer at around 10.2ā9.2 cal. ka BP, when this species lived there. The blue mussel, Mytilus edulis, returned to Svalbard in 2004 following recent warming, and after almost 4000 years of absence, excluding a short re-appearance during the Medieval Warm Period 900 years ago. Mytilus first arrived in Svalbard at 11 cal. ka BP, indicating that the climate was then as least as warm as present. This first warm period lasted from 11 to 9 cal. ka BP and was followed by a period of lower temperatures 9ā8.2 cal. ka BP. After 8.2 cal. ka, the climate around Svalbard warmed again, and although it did not reach the same peak in temperatures as prior to 9 ka, it was nevertheless some 4Ā°C warmer than present between 8.2 and 6 cal. ka BP. Thereafter, a gradual cooling brought temperatures to the present level at about 4.5 cal. ka BP. The warm early-Holocene climate around Svalbard was driven primarily by higher insolation and greater influx of warm Atlantic Water, but feedback processes further influenced the regional climate.ā
Survival of Barents Sea polar bears during low-ice years does not require emigration to another sea ice ecoregion or even another subpopulation area. The eastern Barents Sea (located in Russian territory), as defined by the Polar Bear Specialist Group (see map below), provides ample habitat for polar bears to thrive despite extended fluctuations in seasonal sea ice cover in the western portion. Although it must be frustrating for Norwegian researchers and their colleagues to see ātheirā bears abandoning Svalbard for Franz Josef Land because of recent low ice levels, they are not witnessing a biological catastrophe.
Bottom line: Barents Sea polar bears are loyal to this region because the eastern portion has the habitat they require to thrive even when sea ice cover in the western portion essentially disappears for thousands of years at a time.
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REFERENCES
Aars, J. 2015. Research on polar bears at Norwegian Polar Institute. Online seminar (āwebinarā), January 14. pdf here.
Aars, J., Marques,T.A, Lone, K., Anderson, M., Wiig, Ć., FlĆøystad, I.M.B., Hagen, S.B. and Buckland, S.T. 2017. The number and distribution of polar bears in the western Barents Sea. Polar Research36:1. 1374125. doi:10.1080/17518369.2017.1374125
Aars, J., Marques, T.A., Buckland, S.T., Andersen, M., Belikov, S., Boltunov, A., et al. 2009. Estimating the Barents Sea polar bear subpopulation. Marine Mammal Science 25: 35-52. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1748-7692.2008.00228.x
Amstrup, S.C., Marcot, B.G. & Douglas, D.C. 2007. Forecasting the rangewide status of polar bears at selected times in the 21st century.US Geological Survey. Reston, VA. Pdf here
Amstrup, S.C., Marcot, B.G., Douglas, D.C. 2008. A Bayesian network modeling approach to forecasting the 21st century worldwide status of polar bears. Pgs. 213-268 in Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications, E.T. DeWeaver, C.M. Bitz, and L.B. Tremblay (eds.). Geophysical Monograph 180. American Geophysical Union, Washington, D.C. http://onlinelibrary.wiley.com/doi/10.1029/180GM14/summary and http://alaska.usgs.gov/science/biology/polar_bears/pubs.html
Andersen, M. & Aars, J. 2016. Barents Sea polar bears (Ursus maritimus): population biology and anthropegenic threats. Polar Research 35: 26029. https://www.tandfonline.com/doi/abs/10.3402/polar.v35.26029
Barr, S. 1995. Franz Josef Land. Oslo: Norwegian Polar Institute. ISBN
82-7666-095-9.
Chernova NV, Friedlander AM, Turchik A, Sala E. 2014. Franz Josef Land: extreme northern outpost for Arctic fishes. PeerJ 2:e692 https://doi.org/10.7717/peerj.692 https://peerj.com/articles/692/
Descamps, S., Aars, J., Fuglei, E., Kovacs, K.M., Lydersen, C., Pavlova, O., Pedersen, Ć .Ć., Ravolainen, V. and StrĆøm, H. 2017.Climate change impacts on wildlife in a High Arctic archipelago ā Svalbard, Norway. Global Change Biology 23: 490-502. doi: 10.1111/gcb.13381
Fauchald, P., Arneberg, P., Berge, J., Gerland, S., Kovacs, K.M., Reigstad, M. and Sundet, J.H. 2014. An assessment of MOSJ ā the state of the marine environment around Svalbard and Jan Mayen. Norwegian Polar Institute Report Series no. 145. Available at http://www.mosj.no/en/documents/ [accessed 15 February 2017]
Mangerud, J. and Svendsen, J.I. 2018. The Holocene Thermal Maximum around
Svalbard, Arctic North Atlantic; molluscs show early and exceptional warmth. The Holocene 28(1): 65ā83. http://journals.sagepub.com/doi/abs/10.1177/0959683617715701
Taylor, K.C., Mayewski, P.A., Alley, R.B., Brook, E.J., Gow, A.J., Grootes, P.M., Meese, D.A., Saltzman, E.S., Severinghaus, J.P., Twickler, M.S., White, J.W.C., Whitlow, S., and Zielinski, G.A. 1997.The Holocene-Younger Dryas Transition Recorded at Summit, Greenland. Science 278:825-827. http://science.sciencemag.org/content/278/5339/825
Further proof, 100%: polar bears have had it DIFFERENT in the past. Period. A lot different. They, like all migratory animals, adapt. Period.
Nice study. However, I think the 9ky polar bears survived by eating all of the penguins, and the proof is that there aren’t any penguins there anymore. See, science works both ways.
You know there was an Artic penguin?
https://www.smithsonianmag.com/smithsonian-institution/with-crush-fisherman-boot-the-last-great-auks-died-180951982/
Antarctic penguins get their name from the great auk.
Good article. More evidence that the magnitude of effects not related to anthropogenic causes are so large finding the AGW signal is perhaps futile.
Most of the fracking Holocene was warmer (with less sea ice) in the Arctic than it is today. The Little Age was probably the coldest climatic phase of the Holocene in the Northern Hemisphere. The notion that the retreat in sea ice extent since 1979 (or any time since the 1800’s) is a threat to Polar Bears is perhaps the dumbest, wrongest, goofiest tenets of the Gorebal Warming religion.
Fracking? Wasn’t that invented recently (in geological terms)?
Ohhh…you meant, like, “effing”. Someone’s been watching Battlestar Galactica…
rip
That was a fracking long time ago… Way back in the Pleistocene, when I was in college… LOL!
Oh, you’re missing out then! My 15 yr old daughter and I are watching the early 2000’s remake together, and it’s one of the best shows we’ve ever watched. Truly fantastic!
I tried watching the remake… I was actually looking forward to it… But I just couldn’t get into it. Maybe I just didn’t give it enough of a chance… Maybe it was the fact that when I watched the original series, I was in college, we drank lots of beer, and reenacted the battle scenes by flipping bottle caps at one another… š
How did the Polar Bears handle those hot Russian summers of the Early Holocene?
David Middleton
They handled those hot Russian summers by lounging around on the rocky shoreline getting āfat nā sassyā because those 5,000 years of hot Russian summers (9K to 4K BP) were surely the ābest-test-of-timesā ever endured by the Polar Bear populations.
The Polar Bears just lay snoozing on the beaches waiting for their dinners to be served to them ā¦ā¦. when the female seals came ashore to birth their pups.
As a matter of fact Franz Josefs Land was also warmer than now during the Holocene optimum. A reindeer population existed there, which indicates that there were considerable ice-free and vegetated areas. This population went extinct about 1,300 years ago, during the cold interval between the Roman and Medieval Warm Period.
I’d like to add another thing going for the polar bear: There was probably easier prey for stone age hunters that tasted better. Have there been any “kill strike” bone damage in skeletons of polar bear from stone age hunters? If confronted by larger groups of hunters, they probably stayed close enough to the water to slip away. They are tough animals, not doomed to the fate of other mega fauna.
Most people are too smart to hunt Polar Bears. Their remains are very rare in archaeological deposits – with one notable exception. A stone age people living in the New Siberian Islands during the Holocene optimum apparently hunted them systematically:
https://polarbearscience.com/2013/02/18/the-ancient-polar-bear-hunters-of-zhokhov-island-siberia/
That area has been completely uninhabited since the climate started deteriorating about 4000 years ago.
See https://polarbearscience.files.wordpress.com/2012/11/ancient-polar-bear-remains_crockford-20123.pdf
I thought you couldn’t use radio-carbon dating for things found in the seas?
You can, but you have to apply a (fairly small) correction which of course increases uncertainty a bit.
Poley bears are pretty intelligent mammals ranging over a large habitat. You’d have to be nearly as intelligent as a climate scientist to think they couldn’t adapt to some really quite modest changes.
Susan, keep it up! What a compelling article on the resilience of this magnificent animal. The polar bear is known to be able to swim 600 – 800 km. Now why does one suppose this creature has this capability? Because he needs it, if I may be permitted to answer a rhetorical question.
As a geologist, nearly all our science’s evidence is forensic in character and based on logic, so to a geologist this reads like an ancient manuscript, layers of rock and what’s in them are the pages of this manuscript.
Moreover, in this type of evidence, a good geologist’s training and experience sees so much more than just the evidence of the polar bear’s adaptability. What of the astounding response to environment of Svalbard’s returning long lost mussel, Mytilus edulis and companion SHALLOW WATER molluscs! This makes the polar bear’s aquatics seem commonplace. Do biologists see the magnificent adventure and ballet of the biosphere over time that I do in this? Not only does a creature employ his capabilities to survive in a region, but others wait patiently for millennia at the boundaries of their range to venture in when changes in environment permit.
Let me end with my favorite validation of the geologist’s methods. On similar forms of evidence as in this article, the Eocene Epoch (55Mybp – 33Mybp) was deduced to have been a globally warm time, much warmer than today. A few years ago, chunks of redwood trees were found by miners at the Ekati Diamond Mine at the Arctic Circle at a depth of 300m in the mine. These were actual red wood with the sugary seams of sap preserved and dated at 53Mybp!!
https://www.google.com/amp/s/amp.livescience.com/23374-fossil-forest-redwood-diamond-mine.html
It breaks my heart to see what harm has wilfully been done to to the reputation of science to serve Philistine interests.
Oh my! The redwoods have disappeared from the region around Lac de Gras! What a failure on the part of Save the Redwoods and other similar NGOs. I suppose that it was due to the chilling effect of all of that nasty man-made liquid CO2 freezing everything. But wait, there were no hominids way back then. So what might have been the cause, natural variation? But natural variation doesn’t exist. Just ask any Climate Scientistā¢.
Gary,
Puh-lease! You expect us to believe this carp? Everyone knows Canadian redwoods don’t grow inside mines!
Now, African redwoods, on the other hand…
rip
If trees don’t grow inside mines, how did they get all that coal in there?
Duh, it’s clearly abiotic…
rip
ripshin,
What do you mean? An African or European redwood?
(Paraphrased from one of the best movies of all time.)
Haha…thank goodness somebody got it!
rip
A real Asian member of the subfamily Sequoioideae:
https://en.wikipedia.org/wiki/Metasequoia_glyptostroboides
Of course there was less habitat. During the Holocene Maximum, the Siberian Taiga forests were 200 km further north than they are today, demonstrating hiw much warmer ir was then.
This i creased temperature was not caused by CO2, it was caused by increased orbital obliquity. Since we have low orbital eccentricity at present, high latitude summer warming is currently controlled by obliquity rather than precession. Which is why the Holocene is a longer interglacial than normal (just like 400 k years ago). (Milankovitch insolation comprises both precession and obliquity together.)
Holocene temperatures are actually proportional to orbital obliquity, rather than CO2. CO2 merely follows temperature due to oceanic outgassing. During other ice ages, interglacial temperatures are normally influenced more by precession.
The previous interglacial, the Eemian (MIS 5), lasted 16,000 years, so the Holocene has a long way to go yet to equal that one. The Eemian was also a lot hotter.
But the two interglacials before it were shorter (MIS 7) than or about the same (MIS 9) as the Holocene so far.
The one before those two (MIS 11) however lasted even longer than the Eemian.
The UK was certainly warmer around 6000 years ago.
Because people living on the west coast of Scotland around that time were able to use Hazelnuts as a food supply. Which suggests that at the time the climate was at least as mild as southern England is now.
Everyone seems to miss the simple fact that it is much easier for the Polar bears to catch the seals on land rather than have to go miles out on the ice for lunch….. less ice is actually their preference…only people seem to assume that less ice = less polar = less polar bears….
Of course, seals will preferentially have their young where there is a protective ice pack. The seals will move with the ice, the bears will move to find lunch, everything will be as it is supposed to be. If the environmentalists count bears where there is no ice, they will find a muchly reduced bear population, and blog the world about it.
Keep up the good work Susan.
“First they ignore you, then they laugh at you, then they fight you, then you win.”
perhaps we should consider updating the famous misquote:
“First they smear you, then they try to get you fired, then they try to isolate you, then they avoid debating with you, then they try to confuse the issue in a sea of jargon, then they apply for more funding … then again this might not be such a snappy quote.
But it is a testament to your good science, hard work and tenacity that the past resilience, and present good prospects for Polar Bears are accepted as obvious facts now, and thus their use in AGW scare stories is counter productive.
Jay,
Thanks.
I concur.
Dr. Crockford has been an honest scientist for a number or – probably, very many – years.
I applaud her honesty – and her integrity and persistence.
I do not know if the opposition is political or discriminatory – or some combination.
But that opposition seems ill-focussed.
I like being polite!!
Auto
For all those interested, the article by prof. Mangerud in available (no paywall) on ResearchGate at this adress:
https://www.researchgate.net/publication/318291909_The_Holocene_Thermal_Maximum_around_Svalbard_Arctic_North_Atlantic_molluscs_show_early_and_exceptional_warmth
Also from ResearchGate, similar findings about the Holocene Climate Optimum can be found in this report from Italian professor Orombelli:
“8800 years of high-altitude vegetation and climate history at the Rutor Glacier forefield, Italian Alps. Evidence of middle Holocene timberline rise and glacier contraction”
From the abstract:
“Pollen-stratigraphic evidence of a primary plant succession highlights a lag beween local deglaciation and the first reliable 14C age. The radiocarbon chronology points to a prolonged phase of glacier contraction between 8.8 and 3.7 ka cal BP. Even later the glacier remained within its LIA limits. Between 8.4 and 4 ka cal BP MAT-inferred TJuly fluctuated near 12.4 Ā°C, ca. 3.1 Ā°C higher than today. During this period, a Pinus cembra forest belt grew at 2600m asl with an upper limit of tree groves placed 434 Ā± 310m above the current open forest limit. This Holocene phase of thermal maximum ended between 3.98 and 3.51 Ā± 70 ka cal BP and with a substantial rearrangement of forest composition; temperature reconstruction shows a decrease of 1.8 Ā°C”
Link:
https://www.researchgate.net/publication/323150842_8800_years_of_high-altitude_vegetation_and_climate_history_at_the_Rutor_Glacier_forefield_Italian_Alps_Evidence_of_middle_Holocene_timberline_rise_and_glacier_contraction