The fact that multiyear sea ice got thinner between 2018 and 2021 as documented by a new study, is ultimately good news for polar bears: less multiyear ice compared to first year ice is better for all marine mammals in the Arctic. Polar bears and seals, for example, are dependent on the seasonal ice that forms every winter (Atwood et al. 2016; Durner et al. 2009). Multiyear ice is simply too thick for any purpose except as a summer refuge for polar bears (for which land will do just as well) and a platform for maternity dens over the winter, for which thick first year ice will often do just as well (Anderson et al. 2012; Rode et al. 2018).
According to the press release for the new paper (Kacimi and Kwok 2022):
– End-of-season Arctic multiyear sea ice is about 1.5 feet thinner in 2021 than in 2019
– Arctic Ocean sea ice lost one-third of its volume in the past 18 years
– New pan-Arctic snow depth suggests previous estimates of sea ice thickness may have been overestimated
The authors of the paper also emphasized that there had been ‘negligible’ changes in first-year ice over the same period, so it’s only multiyear ice that’s changing.
But don’t forget that old multiyear ice can be very thick indeed: 2-4 metres, sometimes quite a bit thicker, as is the ice north of Greenland which can be up to 20 metres thick.
Sea ice thickness and sea ice age are not the same thing, but sea ice age provides a proxy for thickness. A study published in 2007 found a dramatic change in the age of sea ice in the central Arctic Basin since the mid-1980s. In 1987, 57 percent of the ice pack was at least five years old, and a quarter of that ice was at least nine years old. By 2007, only 7 percent of the ice pack was at least five years old, and virtually none of the ice was at least nine years old (Maslanik et al, 2007). Multiyear ice coverage actually increased between March 2013 and March 2014, thanks to more ice surviving the summer melt season than had survived in the record-breaking summer of 2012. But overall, multiyear sea ice continues to decline in the Arctic (Perovich et al. 2014).
Areas in the central Canadian Arctic where multiyear ice has been largely replace by first year ice in recent years (such as M’Clintock Channel and Kane Basin) have seen polar bear population numbers grow.
References
Andersen, M., Derocher, A.E., Wiig, Ø. and Aars, J. 2012. Polar bear (Ursus maritimus) maternity den distribution in Svalbard, Norway. Polar Biology 35:499-508.
Atwood, T. C., Marcot, B.G., Douglas, D.C., et al. 2016. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears. Ecosphere 7(6):e01370. Doi: 10.1002/ecs2.1370
Durner, G.M., Douglas, D.C., Nielson, R.M., Amstrup, S.C., McDonald, T.L., et al. 2009. Predicting 21st-century polar bear habitat distribution from global climate models. Ecology Monographs 79: 25–58.
Kacimi, S. and Kwok, R. 2022. Arctic snow depth, ice thickness, and volume from ICESat-2 and CryoSat-2: 2018–2021. Geophysical Research Letters 49(5): e2021GL097448. https://doi.org/10.1029/2021GL097448
Rode, K.D., Olsen, J., Eggett, D., et al. 2018. Den phenology and reproductive success of polar bears in a
changing climate. Journal of Mammalogy 99(1):16-26. https://doi.org/10.1093/jmammal/gyx181
Too many of the murderous buggers around these days, time for a cull.
Didn’t the DMI change its method of measuring Arctic Sea Ice at the backend of last year?
“– End-of-season Arctic multiyear sea ice is about 1.5 feet thinner in 2021 than in 2019
– Arctic Ocean sea ice lost one-third of its volume in the past 18 years
– New pan-Arctic snow depth suggests previous estimates of sea ice thickness may have been overestimated”
And so what? Looking at ice core records over the long past shows extraordinary fluctuations and variations. There are NO horizontal lines in this or any data. Peak ice in the Arctic is when temperatures in the lower latitudes are already on they way up to Summer maximums and minimum ice is when temperatures in the lower latitudes are already on they down up to Winter minimums. Multi-year ice in the Arctic is never that old because of the amount of ice that is pushed out of the Arctic basin. Either way I’m sure the Polar Bears will figure out what to do whatever the ice does.
Well if the multiyear ice is getting thinner that’s not good news for the ice cap or planet, is it?
Meanwhile:
In the south, Antarctic sea ice recently reached its late-summer minimum, dropping below all previous minimum ice extents in the satellite record… . For the first time since the satellite record began in 1979, extent fell below 2 million square kilometers (772,000 square miles), reaching a minimum extent of 1.92 million square kilometers (741,000 square miles) on February 25.
NSIDC
Cold air masses from the north are reaching the western US again.
Prior to DMI tampering with the data last autumn, Arctic sea ice had got thicker in 2021:
https://notalotofpeopleknowthat.wordpress.com/2021/12/10/sea-ice-data-tampering-at-dmi/
If this trend continues, the arctic will be ice-free by 2013. Oh wait…
After all these years, Alarmists have never found a better icon than polar bears for pushing their narrative, and they are still being shamelessly used on kids. One photo of a polar bear “stranded” on an ice floe is enough to elicit great sobbing and wailing in kids about their “sad” situation, and how it’s all our fault because Climate Change.
More hungry polar bears will hunt seals. That’s good news for the polar bears but probably not good news for the seals. 😉
As the ice is growing in area they had to make it thinner.
It is all so corrupt.
the claim that they know how thick the ice is is false.
I have a question I would like opinion on. A prominent New Zealand main stream media source, Newshub, has published an article in which climate scientists are saying temperatures in East Antarctica are 40 degrees C above normal for this time of year. They are currently at -10C. When they are normally -50C.
Yeah, what?
At the moment it is early autumn in Antarctica. Surely -50C would be the depths of winter?
Any ideas on this?
If we could only warm the planet we could thin the ice ourselves. Eventually we could get rid of most of the bears and grow grapes for wine. But, sadly, it appears our activities have little to no effect on the climate, despite the most narcissistic of men wishing otherwise.
Why is the ice getting thinner ? Is it getting warmer. ?