Last week’s media coverage made me realize that James Hansen’s testimony to a US Senate committee in 1988 provided well-timed answer to a vexatious problem facing polar bear biologist Ian Stirling. Thirty years ago, Stirling was struggling to understand why polar bear productivity in Western Hudson Bay had dropped. He was ripe for the suggestion from Hansen (and his follow-up paper) that human-caused global warming could be the explanation. An interview with Stirling and colleague Andrew Derocher published in 2016 helps connect the dots.
Many bears were in poor condition in the fall of 1983 (Calvert et al. 1986:19, 24; Ramsay and Stirling 1988). In general, the 1980s saw weights of bears decline and cub mortality increase, with a marked increase in the loss of whole litters over what had been documented in the 1960s and 1970s (Derocher and Stirling 1992, 1995).
Until Hansen and climate change came along, density-dependent effects (such as the number of bears out-pacing food supply) were seen as the most likely explanation. But sea ice decline blamed on human-caused global warming was suddenly a new possibility that Stirling soon embraced (Stirling and Derocher 1993). By the late 1990s, sea ice coverage on Hudson Bay had indeed declined but the correlation with polar bear productivity produced a weak trend that was not statistically significant (Stirling et al. 1999).
The 1999 Stirling paper did not provide scientific evidence to explain the 1980s decline in productivity as much as it presented a novel scapegoat to blame when a more plausible explanation could not be made.
Bottom line: Global warming could not have been the proximate cause of the productivity changes in WH polar bears documented during the 1980s but Stirling spent the next two and a half decades vigorously pushing climate change as the cause of all polar bear ills. Continue reading
Posted in Conservation Status, Life History, Population, Sea ice habitat
Tagged body condition, climate change, decline, density-dependent response, global warming, Hansen, natality, polar bear, productivity, sea ice, Stirling, survival
In case you missed it — or missed the significance of it — polar bear specialist Mitch Taylor correctly pointed out in his recent essay (a response to the New York Times article that appeared Tuesday (10 April) about the Harvey et al. (2018) BioScience paper) that the IUCN Polar Bear Specialist Group have given up using computer models of future sea ice extent based on rising CO2 levels supported by the IPCC.
Their latest assessment (Regehr et al. 2016) does not link polar bear survival models to climate modeled forecasts of Arctic sea ice decline but rather to an assumption that declines already documented will continue in linear fashion over this century.
This means that CO2 emissions blamed on human fossil fuel use is no longer directly tied to the predicted future decline of polar bear numbers: IUCN polar bear specialists simply assume that sea ice will continue to decline in a linear fashion with no cause attributed to that decline except the broad assumption that anthropogenic climate change is to blame for Arctic sea ice declines since 1979.
No wonder former USGS polar bear biologist Steve Amstrup never refers to this IUCN PBSG study: he and the organization that now employs him, Polar Bears International, are still firmly wedded to the concept that CO2 is the sea ice control knob.
Posted in Advocacy, Conservation Status, Sea ice habitat
Tagged Amstrup, climate models, CO2, decline, general circulation models, IPCC, Mitch Taylor, PBSG, polar bear, predictions, Regehr, sea ice, survival
There is no evidence that slightly less winter sea ice than the average since 1979 has had any negative impact on polar bear health or survival: the difference is simply not biologically meaningful to Arctic animals.
Polar bear on winter sea ice around the yearly maximum in the Beaufort Sea, 2010 (March 21).
NASA’s 23 March 2018 announcement regarding the Arctic sea ice maximum this year:
“Sea ice in the Arctic grew to its annual maximum extent last week, and joined 2015, 2016 and 2017 as the four lowest maximum extents on record, according to scientists at the NASA-supported National Snow and Ice Data Center (NSIDC) and NASA.”
Except, what they don’t tell you is that 2006 had almost the same extent as 2018 and 2006 wasn’t far behind according to the official, averaged data presented at NSIDC’s Arctic Sea Ice News & Analysis:
Current conditions at the winter maximum (at 17 March 2018, from NSIDC Masie, extent measured at 14.7 mkm2, using software able to discern more ice than used for the figures in Table 1), shown below: Continue reading
Posted in Sea ice habitat
Tagged Arctic, climate change, global warming, health, maximum, melting, NASA, polar bear, sea ice, survival, warm, winter
Polar bear specialists Andrew Derocher and Steven Amstrup recently spent inordinate energy trying to refute the opinion piece I’d written for the Financial Post in celebration of International Polar Bear Day last month, ignoring my fully referenced State of the Polar Bear Report for 2017 that was released the same day (Crockford 2018) and the scientific manuscript I’d posted last year at PeerJ Preprints (Crockford 2017).
Their responses use misdirection and strawman arguments to make points. Such an approach would not work with the scientific community in a public review of my paper at PeerJ, but it’s perfect spin for the self-proclaimed “fact-checking” organization called Climate Feedback. The result is a wildly ineffective rebuttal of my scientific conclusion that Amstrup’s 2007 polar bear survival model has failed miserably.
This is Part 2 of my expose, see Part 1 here.
Posted in Conservation Status, Population, Sea ice habitat, Summary
Tagged Amstrup, bearded seal, Beaufort, Chukchi Sea, Climate Feedback, damage control, Derocher, ESA, fact checker, failed predictions, ice-free, observations, polar bear, predictions, ringed seal, sea ice, spin, spring, Stirling, summer, survival, thick ice, threatened
In conjunction with the launch of my State of the Polar Bear Report in Toronto next week, Benny Peiser (from the Global Warming Policy Foundation) and I will be participating in a coffee house discussion about polar bear conservation and survival issues on the evening of Tuesday, 27 February 2018 at 8:30 pm.
If you’re in town, come and celebrate International Polar Bear Day with a frank discussion about polar bear science.
I am very much looking forward to meeting the public at this evening discussion and to chat with media representatives and colleagues at the press luncheon in the early afternoon. Journalist/opinion writer Terry Corcoran recently billed the luncheon as part of a Polar Bear Battle since conservation organization Polar Bears International (where biologist Steven Amstrup, co-author of the Harvey et al. Bioscience paper and developer of the failed 2007 polar bear survival model, is employed as chief scientist) is holding a gala fundraiser dinner the same night, just a block away.
In addition to Benny Peiser from GWPF, a number of familiar names will be at the State of the Polar Bear launch and press luncheon, including Terry Corcoran, Larry Soloman, Joe Oliver and Conrad Black (all journalist/opinion writers at the Financial Post and/or National Post), journalist/writer Donna Laframboise who blogs at No Frakking Consensus, as well as science colleagues Chris Essex, Ross McKitrick, and Steve McIntyre of Climate Audit fame. Details below.
Posted in Advocacy, Conservation Status, Population, Summary
Tagged conservation, facts, Green Beanery, international, models, Polar Bear Day, report, science, survival, unbiased
The really significant content of a new paper being heavily-hyped by the media1 is what wasn’t said rather than what the authors discovered about metabolic rates and weight maintenance of a small sample of nine Southern Beaufort Sea bears in 2014 to 2016 (Pagano et al. 2018; Whiteman 2018).
This paper does not document starving or dying bears but merely found some (5/9) that lost weight when they should have been gaining, given that early April is the start of the ringed seal pupping season (Smith 1987) and the intensive spring feeding period for polar bears (Stirling et al. 1981).
The question is, why were Southern Beaufort Sea polar bears off Prudhoe Bay (see map of the study area below), still hunting and capturing only adult and subadult ringed seals from sea ice leads when newborn ringed seal pups and their mothers should have been plentiful and relatively easily available in their birth lairs on the sea ice (see below)?
“Using video collar data, we documented bears’ hunting behavior and foraging success. Bears used sit-and-wait tactics to hunt seals 90% of the time, and stalking comprised the remaining 10% of hunts (movies S1 to S4) (19). Bears that successfully killed and ate adult or subadult ringed seals either gained or maintained body mass, whereas bears that only scavenged or showed no evidence of eating lost mass.”
There was no discussion in the paper of ringed seal birth lairs, or sea ice conditions at the time of the study, but several mentions about what might happen in the future to sea ice and potential consequences for polar bears. The press release did the same.
However, as you’ll see by the sea ice thickness maps below, there may be good reason for the lack of ringed seal lairs, and a general lack of seals except at the nearshore lead that forms because of tidal action: the ice just a bit further offshore ice looks too thick for a good crop of ringed seals in all three years of the study. This is reminiscent of conditions that occurred with devastating results in the mid-1970s and mid-2000s (Burns et al. 1975; Cherry et al. 2009; Harwood et al. 2012, 2015; Pilfold et al. 2012; Stirling 2002, Stirling et al. 1987). Those events affected primarily bears in the eastern half of the Southern Beaufort and were almost certainly responsible for the recorded decline in SB bear numbers in the 2001-2010 survey (Bromaghin et al. 2015; Crockford 2017; Crockford and Geist 2018).
It seems very odd to me that Pagano and colleagues suggested no reasons for the unexpectedly poor showing of polar bear hunting success during their study except a bit of hand-waving about higher-than-we-thought metabolic rates in the bears. For years, I’ve worried that the inevitable next episodes of thick Southern Beaufort spring ice would cause problems for polar bears and seals but we wouldn’t know it because whatever effects were documented would be blamed on reduced summer ice: I suspect that time may have come.
Figure 1 from Pagano et al. 2018 cropped to show only the study area off Alaska.
Posted in Advocacy, Conservation Status, Sea ice habitat
Tagged Beaufort Sea, climate change, global warming, polar bear, sea ice, starving, struggling, survival, threatened, trouble, USGS, wasting, worse than we thought
There is still a huge swath of highly concentrated thick first year ice (>1.2m) over most of Hudson Bay this week (19 June 2017) and even in the NW quadrant (the closest proxy we have for Western Hudson Bay), the weekly graph shows levels are greater than 2016, when WHB bears came off the ice in good condition about mid-July. All of which indicates 2017 won’t be an early sea ice breakup year for WHB polar bears.
There is thick first year ice (>1.2m, dark green) in patches along the west coast in the north and south. Thick first year ice also extends into Hudson Strait and Baffin Bay, with some medium first year ice (0.7-1.2m thick, bright green) along the central and southern coasts of WHB. Note the red triangles incorporated into the thick ice of Hudson Strait in the chart above: those are icebergs from Greenland and/or Baffin Island glaciers. A similar phenomenon has been noted this year off northern Newfoundland, where very thick glacier ice became mixed with thick first year pack ice and were compacted against the shore by storm winds to create patches of sea ice 5-8 m thick.
Compare the above to what the ice looked like last year at this time (2016 20 June, below). There is more open water in the east this year (where few WHB bears would likely venture anyway) but less open water around Churchill and Wapusk National Park to the south than there was in 2016:
We won’t know for several more weeks if most WHB bears will come ashore at about the same time as last year (early to mid-July) or whether they will be in as good condition as they were last year (because winter conditions may not have been similar).
But so far, sea ice conditions are not looking as dire as the weekly “departure from normal” chart (below, 19 June 2017) might suggest (all that “less than normal” red and pink, oh no!!):
Posted in Conservation Status, Life History, Sea ice habitat
Tagged breakup, concentration, early breakup, extinction, habitat, ice charts, observations, polar bear, predictions, sea ice, survival, trends