Guest essay by Dr. Susan Crockford
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 studyconducted 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 thatthere 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 havecontinued 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 increasingbecause 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.
Prediction 8. Western Hudson Bay (WHB) polar bears can be used to predict how bears living in Foxe Basin, and Davis Strait are doing because these are all similar ‘sea ice ecoregions’, says the Circumpolar Action Plan for future research proposed by Dag Vongraven and colleagues in 2012.
FAIL – WHB bears not only have variable breakup and freeze-up dates to contend with but also face occasional years with thick spring ice and springs with either very thick or very thin snow cover that strongly affects the availability of their ringed seal prey. Davis Strait bears, on the other hand, face some variability in sea ice conditions but have access to a super-abundant supply of harp seal prey in spring. With WHB polar bears by far the more vulnerable to decline from natural variations in sea ice and prey availability than Davis Strait bears, the plan to treat these two regions as equivalent is a farce and totally undermines the proposed Circumpolar Action Plan.
Prediction 9. Continued late formation of fall sea ice off Svalbard in the Barents Sea will devastate polar bears that traditionally den in this region.
FAIL – Preliminary results from the latest population count of Svalbard area polar bears showed a 42% increase over the estimate for 2004, despite very late ice formation in the fall of 2013 around maternity denning areas. Other research has shown that bears move back and forth readily between Svalbard, Norway and Franz Josef Land, Russia (which so far has always had sea ice by late fall). This means that Svalbard bears have been able to adapt easily to recent low ice conditions.
FAIL – Sea ice at September has been variable since 2007 but there has been no declining trend, a pattern sea ice experts admit may continue for 10 years or more beyond 2014 even if declining sea ice predictions are true (Swart and colleagues, 2015). In other words, CO2 levels have not been the control knob for polar bear health.
Polar bears are not fragile canaries in an Arctic climate-change coal mine but resilient and adaptable predators remarkably suited to their highly variable habitat.
Here’s a summary of what the 2015 Red List assessment (Wiig et al. 2015) said:
The previous status of ‘Vulnerable’ was upheld but no projections were made beyond 2050. They said there is only a 70% chancethat numbers will decline by 30% over the next 35 years, which is only slightly higher than a 50:50. It also means there is a 30% chance that the numbers WILL NOT decline by 30% over the next 35 years.It stated explicitly that the risk of a population decline of 80% or greater by 2050 is virtually zero (pg. 16).
In other words, the status of ‘Vulnerable’ is based only on apossible decline in population numbers, despite their current high numbers, and there is no imminent risk of extinction. The current population trend is stated as UNKNOWN.
Read her entire essay here