The US National Snow and Ice Data Center (NSIDC) is a key locus for current studies of the Earth’s cryposphere (AKA, “science-in’ the hell out of the melting ice”). Their web site has tons of information and pointers to lots more. Among other things, there is a “Greenland and Antarctic Ice Sheet Today”, (“Follow the melt year-round with daily images & scientific analysis”)
The NSIDC also issues reports on trends and predictions.
This month the Arctic Sea Ice News and Analysis blog reported that observations indicate that “Antarctic sea ice extent sets a new record low” in 2022 [2]. In fact, it has tracked well below any measured year. (The data only extends back to 1975.) (The BBC reports that cruise ships confirm that most of the area is ice free [1].)
The sea ice is the floating ice that builds up in the southern winter and melts off in the summer. The minimum occurs at the end of the summer, i.e., about mid to late February.
However, sea ice is definitely influenced by warm water and air conditions, and also by strong winds and storms. A low extent suggests that many parts of the Antarctic coast are warmer than usual. Probably.
Sea ice does not influence mean sea level much because it is floating on the water. But it is an important driver of ocean currents. The floating ice is frozen from the surface of the sea, which leaves behind the salt in the water under the ice. This saltier water is denser and sinks, driving ocean currents. This moves heat and nutrients through the ocean.
It is important to note that the overall story is that the sea ice extent, and by implication, sea and air conditions, have been variable in the last decade. While 2021 and 2022 were record low sea ice extents, other recent years were as high as any recorded years. The overall trend line has a slope about zero.
Since we only have good data for 40 some years, we really don’t know if this variability is common or not, or what longer term trends might show. The older data we do have suggests long fluctuations occured. They also suggest that the southern ice hasn’t followed the same trends as the Arctic and Greenland. So there is a lot of uncertainty.
All the more reason to keep “following the melt”, to see if this sudden dip persists, and if so, what caused it.
- Jonathan Amos and Erwan Rivault, Antarctica sea-ice hits new record low, in BBC News – Science February 16, 2023. https://www.bbc.com/news/science-environment-64649596
- National Snow and Ice Data Center (NSIDC), Antarctic sea ice extent sets a new record low, in Arctic Sea Ice News and Analysis, February 14, 2023. https://nsidc.org/arcticseaicenews/2023/02/antarctic-sea-ice-extent-sets-a-new-record-low/
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