Susan Crockford
Sea ice experts at the US National Snow and Ice Data Center just confirmed my suspicion that the huge area of open water in eastern Hudson Bay during May this year was caused by winds, not ice melt. In other words, it’s a rare occurrence but not a sign of extra-early sea ice melt caused by global warming.
Money quote: “Unusual strong and persistent winds from the east caused the low extent.”
May sea ice Hudson Bay
From the NSIDC report (June 4), a NASA image of Hudson Bay taken 26 May 2024:
The graph below is from the same report, showing the “unprecedented” (since 1979 only) nature of this wind-driven event:
The Canadian Ice Service shows this in regional context for the first week of June in their stage of development chart (i.e. ice thickness, where medium green is 70-120 cm thick, dark green 120-200 cm or more):
Even pessimistic polar bear specialist Andrew Derocher admitted last week that Western Hudson Bay polar bears are largely unaffected by the open water on the bay since they are concentrated in the western half of the bay. The bears do this most years in late spring, in fact, even when there is more ice available. Derocher’s tracking maps for 31 May 2024 and 1 June 2019 are below:
Even by today, 9 June, there is still ice in the western half of James Bay and Hudson Bay:
May Arctic sea ice
Overall, however, the NSIDC report also showed that sea ice for May was about what it has been since 2004 (with some variation), with the average this year at 12.78 mkm2:
Sea ice extent at 1 June 2024 shown below:
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Do the bears really need the sea ice?
Yes, during the spring seal whelping season when they hunt 70-85% of their annual caloric intake. Just looked it up specific to Hudson Bay. Depends on the seal species a bit, but the peak whelping months are March, April, May. So sea ice not needed now in mid June.
“Yes, during the spring seal whelping season…”
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Sounds more like the bears need the seals more than the sea ice. I’m guessing the seals haul out on the ice to have their pups because if they hauled out on the beach, the bears would really have a field day.
The seals need the ice, not the bears.
Ringed seals’ whelping dens are on shore fast ice.
Polar bears in some areas eat baby seals when adult seals come ashore to give birth, and some open water is needed near shore for that. In Hudson Bay, which is far from the southern seas in which the seals live during winter, there are probably not many seals, so polar bears there will eat mostly fish.
For a polar bear to find fish, there has to be some open water, but an ice floe or the edge of pack ice provides a convenient place for the bear to rest while waiting for an unsuspecting fish, without the bear having to waste energy swimming. During summer, when Hudson Bay is mostly open water, the polar bears go ashore to hunt on land, or fish in rivers.
The polar bears use the sea ice as a springboard when it is convenient for them, but they also need some open water for access to food. If Hudson Bay remained frozen year-round, the polar bears would starve.
“Polar bears in some areas eat baby seals when adult seals come ashore to give birth, and some open water is needed near shore for that.”
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And the seals need some open water for what, to get away from the bears? So the adults flee into the water and the bears get the pups. If the adult seals didn’t have open water near by, they would be lunch for the bears, not the pups.
Sort of the Hudson Bay version of a polynya.
Even with this large open area, Arctic sea ice extent yesterday was still above the 2011-20 average for that date.
The media will attribute this to Arctic amplification.
There will be those that claim the increased wind is due to CO2.
When does seal whelping season end? If it is after the polyna formed, it should not affect bears.
See above. Depends a bit on seal species, but for Hudson Bay all species whelp March-April-May according to Canada.
I do not see data for wind speed, average or gusts.
Near Ellensburg, WA — famous for winds — today the highest gust was 40 mph.
50 mph is rare, but the continuity of above 25 is no fun.
Anyway, my question is what sort of wind is necessary to break up an ice cover
and clear 1/3 of Hudson Bay?
Great question. So I just researched it out of personal curiosity.
NSIDC says HB polynya was caused by ‘unusually strong and persistent easterlies’ not seen since satellite records began in 1979. True; Susan said that. Not very quantitative—NSIDC should do better.
Went to Saskatchewan Province Hudson Bay weather reports. Peak easterlies for May ranged from 23-35 mph (steady, not higher gusts) at 2 meters. OK strong days long peaks caused by per Sask HB weather map an unusual Ehigh/lowW weather system configuration. What about average?
Found weatherspark.com for Hudson Bay for May. Average MAY windspeed only about 5.7mph. and 40% of the month was easterlies—aha, by the low average the only direction with strong winds in May. Rest of the month inference from average essentially no wind at all from any other direction.
23-35mph easterlies about 40% of the month is what done it.
Well done.
I’m now averaging 32, with gusts of 45 and 46.
If I had any ice, it would be blown to Idaho.
The polar bears will be fine so long as they aren’t over hunted.
The only thing keeping black bears from being as common as deer in southern New England is hunting.
What if there was little ice in Hudson Bay? Think of the economic benefits of that vast sea if it had a mild climate. So we should not want that to happen because of ANY wildlife? Screw the wildlife- they’ll survive. Coyotes are now common in downtown Bah-stin. Eagles are abundant now in New England.
If Hudson Bay is totally full of sea ice.. the Hudson Bay PBs can’t get at their major food source.
Ice-sea boundary is absolutely important.
If Hudson Bay is totally full of sea ice.. the Hudson Bay PBs can’t get at their major food source.
Ice-sea boundary is absolutely important.
Don’t tell them there is wind there. They’ll have the place full of windmills.
Hmmm…. Windmills on icebergs does solve a host of problems.
Unfortunately one cannot wifi much power.