Failed Predictions About Polar Bears

Here are 5 or the 10 failed predictions regarding Polar Bears via What’s Up With That?

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).

FAILA 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.

(…read the other five…)

Facebook Comments