Grim predictions of the imminent demise of polar bears – their “harsh prophetic reality” as it’s been called – have been touted since at least 2001. But such depressing prophesies have so widely missed the mark they can now be said to have failed.
While polar bears may be negatively affected by declines in sea ice sometime in the future, so far there is no convincing evidence that any unnatural harm has come to them. Indeed, global population size (described by officials as a “tentative guess“) appears to have grown slightly over this time, as the maximum estimated number was 28,370 in 1993 (Wiig and colleagues 1995; range 21,470-28,370) but rose to 31,000 in 2015 (Wiig and colleagues 2015, [pdf here] aka 2015 IUCN Red List assessment; range 20,000-31,000).
These ominous prophesies have been promoted primarily by Ian Stirling, Steven Amstrup, Andrew Derocher and a few other IUCN Polar Bear Specialist Group (PBSG) members but ironically, it’s data collected by their colleagues that’s refuted their message of doom.
Here are the predictions (in no particular order, references at the end):
Prediction 1. Western Hudson Bay (WHB) polar bear numbers will continue to decline beyond 2004 due to ever-earlier breakup and ever-later freeze-up of sea ice.
FAIL – An aerial survey conducted by Seth Stapleton and colleagues (2014) in 2011 produced an estimate of about 1030 bears and their report stated:
“This figure is similar to a 2004 mark–recapture estimate but higher than projections indicating declining abundance since then.”
This 1030 figure is the one being used by the IUCN PBSG and Environment Canada for WHB, as a limited mark-recapture study conducted the same year (Lunn and colleagues 2014) did not survey the entire WHB region and therefore not comparable to the 2004 count.
Prediction 2. Breakup of sea ice in Western Hudson Bay (WHB) will come progressively earlier and freeze-up dates progressively later (after 1999), as CO2 levels from burning fossil fuel increase global temperatures.
FAIL – Researchers Nick Lunn and colleagues (2014) determined that there has been no trend in breakup or freeze-up dates between 2001 and 2010. While no analyses of breakup or freeze-up dates for WHB since 2010 have been published, this pattern seems to have continued to at least 2015.
Prediction 3. Chukchi Sea polar bears will be the most harmed by summer sea ice declines because they experience some of the largest sea ice losses of any subpopulation (and thus, the longest open-water season each year).
FAIL – A recent study of Chukchi bears (2008-2011) found them in better condition than they were in the 1980s when summer open-water seasons were short – indeed, only Foxe Basin bears were fatter than Chukchi bears. They were also reproducing well (Rode et al. 2010, 2013, 2014), with some females raising litters of triplets (see lead photo), a rare sight outside Western Hudson Bay.
Prediction 4. Cannibalism will increase as summer sea ice extent declines worsen.
FAIL – Cannibalism is a natural phenomenon in polar bears and none of the few incidents reported recently have involved obviously thin or starving polar bears (even the most recent example, filmed in mid-August 2015 in Baffin Bay when sea ice levels in the region were high), despite the fact that 2012 recorded the lowest summer ice extent since 1979. Incidents of cannibalism cannot be said to be increasing because there is no scientific baseline to which recent occurrences can be compared.
Prediction 5. Drowning deaths of polar bears will increase as summer sea ice continues to decline (driven home by a high-profile incident in 2004).
FAIL – There have been no further confirmed reports of polar bear drowning deaths associated with extensive open water swimming since that contentious 2004 event, even though the two lowest extents of summer sea ice have occurred since then (2007 and 2012). A more rigorous study of swimming prowess found polar bears, including cubs, are capable of successfully making long-distance swims. Indeed, challenging open-water swims don’t happen only in summer: in late March 2015, a polar bear swam through open water from the pack ice off Newfoundland to the Hibernia oil platform well offshore.
Prediction 6. There will be more and more problems onshore in summer with starving polar bears because of reduced sea ice.
FAIL – There have been more problem bears in summer over the last few years in Western Hudson Bay as well as other regions but few of those bears were shown to be thin or starving. A well-publicized attack occurred in Churchill in the fall of 2013 but was not associated with an especially early break-up of sea ice nor a late freeze-up. Incidents last summer in the Kara Sea (Russia) involved bears in good condition. Polar bears are potentially dangerous no matter what their condition but death by starvation of young or old bears (or injured ones) are natural events that occur often, not evidence of declining sea ice.
Prediction 7. Southern Beaufort Sea polar bears can be used to predict how bears living in the Chukchi Sea and the Barents Sea are doing because they are similar ‘sea ice ecoregions’, says the Circumpolar Action Plan for future research proposed by Dag Vongraven and colleagues in 2012.
FAIL – Recent research has shown that Chukchi Sea bears actually fared better with the long open-water seasons of the late 2000s than in the short seasons of the 1980s. In contrast, Southern Beaufort Sea bears have suffered profoundly from periodic episodes of thick spring ice (every 10 years or so since the 1960s), a phenomenon that is unique to that region. In fact, sea ice conditions for Chukchi Sea and Southern Beaufort bears could hardly be more different. With Southern Beaufort bears the more vulnerable to decline from natural variations in sea ice, the plan to treat these two regions as equivalent is a farce and totally undermines the Circumpolar Action Plan proposed by the IUCN PBSG.