There is no evidence that slightly less winter sea ice than the average since 1979 has had any negative impact on polar bear health or survival: the difference is simply not biologically meaningful to Arctic animals.
Polar bear on winter sea ice around the yearly maximum in the Beaufort Sea, 2010 (March 21).
NASA’s 23 March 2018 announcement regarding the Arctic sea ice maximum this year:
“Sea ice in the Arctic grew to its annual maximum extent last week, and joined 2015, 2016 and 2017 as the four lowest maximum extents on record, according to scientists at the NASA-supported National Snow and Ice Data Center (NSIDC) and NASA.”
Except, what they don’t tell you is that 2006 had almost the same extent as 2018 and 2006 wasn’t far behind according to the official, averaged data presented at NSIDC’s Arctic Sea Ice News & Analysis:
Current conditions at the winter maximum (at 17 March 2018, from NSIDC Masie, extent measured at 14.7 mkm2, using software able to discern more ice than used for the figures in Table 1), shown below: Continue reading
Posted in Sea ice habitat
Tagged Arctic, climate change, global warming, health, maximum, melting, NASA, polar bear, sea ice, survival, warm, winter
Here’s a polar bear habitat update for early March: some folks are wringing their hands over the relatively extent of ice this season but ice maps show that as far as polar bear habitat is concerned, conditions are not materially different this year from what they were in 2006 or 2017. There is still plenty of late winter sea ice for polar bears needing a platform from which to hunt Arctic seals, which in some areas will have already begun giving birth to their fat furry pups (harp seals first, other species later).
The MASIE map for 5 March 2018 (Day 64) shows ice extent at 14.5 mkm2:
Posted in Life History, Sea ice habitat
Tagged extent, habitat, hunt, March, maximum, platform, polar bear, sea ice, seals, winter
Never mind that the sea ice maximum this year came almost a month later than last year (and close to latest since 1979) – and was lower by only .02 – the US National Sea Ice Data Center (NSIDC) today trumpeted a new record low. What this means to polar bears, if anything, remains to be seen.
2015: maximum set February 25 (day 56), at 14.54 mkm2
2016: maximum set March 24 (day 84), at 14.52 mkm2
[The difference in area? Smaller than the Islands of the Bahamas]
Latest maximum extent (since 1979) occurred in 2010 on April 2 (Day 92).
The average date for maximum extent is March 12.
I note, however, that given the lateness of the winter sea ice surge meant that the amount of ice present at 24 March 2016 (see NSIDC Interactive) was more than was present on the same date in 2006, 2007 and 2015.
Clearly, there was plenty enough sea ice in the spring of those years for most polar bears to hunt seals successfully and put on the weight they needed to survive the summer fast ahead. I see no reason to expect 2016 to be different.