Dr. Susan Crockford
Sea ice is nicely above current ranges for this time of 12 months within the Southern Beaufort and solely time will inform if that’s unhealthy information for polar bears. Seals want the open water that early summer season polynyas present with a purpose to feed and a few polar bears make use of the searching alternatives (Stirling and Cleator 1981; Stirling et al. 1981).
It’s been a decade since there was this little open water initially of summer season within the western North American Arctic, particularly the Southern Beaufort. It’s trying unlikely there will probably be in depth open water till nicely into July, which can lead to many fewer bears on shore in early summer season. Recall that in July 2019, NOAA workers counted 31 fats, wholesome bears onshore alongside the Alaska coast.
Previous and Current circumstances
The Cape Bathurst polynya within the Jap Beaufort Sea west of Banks Island was often distinguished in Could throughout the late Seventies (photographs under from Smith and Rigby 1981):
As you’ll be able to see, this polynya was current in basic formation at Could 15 this 12 months:
Nonetheless, by early June it had nearly totally re-frozen:
Now, on the first day of summer season, the polynya is barely simply beginning to open again up once more and the ice surrounding it’s thick multiyear ice (brown) and thick first 12 months ice >1.2m (darkish inexperienced):
The chart under exhibits there may be extra ice than regular within the Jap Beaufort (blue):
The basic CIS chart exhibits what this seems like as ice protection vs. open water:
Examine the above chart for this 12 months (above) to earlier years (under).
On or about the identical date going again in time exhibits how uncommon this case is: there hasn’t been this little open water since 2013.
References
Stirling, I. and Cleator, H. (eds). 1981. Polynyas within the Canadian Arctic. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.
Smith, M. and Rigby, B. 1981. Distribution of polynyas within the Canadian Arctic. In: Polynyas within the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 7-28. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.
Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas within the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa. Pdf of pertinent excerpts of above papers right here.
