By Dr Susan J Crockford
Polar Bear Science Past and Present
Polar bear habitat for June — the last month of spring in the Arctic — is still within 2 standard deviations of the long-term average despite sea ice experts’ predictions that catastrophic declines can be expected any year now.
Oddly, the National Snow and Ice Data Center (NSIDC) employees who wrote up the sea ice summary for June felt it appropriate to bring up a recently-published prediction of impending doom for Southern Hudson Bay polar bears based on a sea ice prediction (Stroeve et al. 2024), which I covered here. The inclusion of this topic is a naked promotion of the Stroeve sea ice modelling paper which not only doesn’t fit the reality of this year’s sea ice conditions but their discussion doesn’t include a single piece of evidence that Southern Hudson Bay polar bears came off the ice earlier than usual.
Extent this year for June, at 10.9 mkm2, compared to previous years was just about exactly what it was in 2006 and slightly lower than it was last year, as the graph below shows:
Southern Hudson Bay
The NSIDC report states: “The average date for ice retreat of southern Hudson Bay ranges between mid-June to late-July, so there is typically enough ice available for polar bears to hunt ringed seal pups, a major food source for them. If the ice breaks up too early, as is the case this year, the bears are stranded on land for more of the summer and autumn season, which extends their annual fasting period.”
First of all, polar bears do not “hunt ringed seal pups” from mid-June to late July in Hudson Bay. Young seals have been weaned by that time and are out feeding in open water. The only potential prey are adult and subadult seals that may be resting on sea ice while they are moulting, but it is very rare for bears to successfully hunt these older seals since they are experienced enough to be ever-vigilant and predator-savvy. As I have pointed out countless times, polar bears may stay on the ice into July or even August if they can but it is not to hunt seals.
Moreover, there was still ice in James Bay at 18 June (see chart below), so breakup wasn’t unusually early and there was still abundant ice along the SW shore of Hudson Bay where many SH bears come off the ice.