北极和南极海冰的冷却效应以及海冰范围都在下降

Geophysical Research Letters, 17 July 2024

Arctic sea ice has been called the “Earth’s refrigerator,” cooling the planet by reflecting the sun’s rays. Its area (or extent) has been decreasing for several decades, but the degree to which this has impacted sea ice’s cooling effect has been debated, for example because some models have shown that cloud cover might increase as sea ice declines, potentially offsetting the loss of sea ice since clouds also reflect sunlight back into space. A study released this week however, using high-performance computational techniques together with satellite observations of total reflectivity from the 1980’s onwards, confirms not only that this cooling effect has decreased in the Arctic, but also from much more recent losses of Antarctic sea ice. In the Arctic, cooling has decreased by 17-22% between the period of 1980-88 versus 2016-2023. Surprisingly however, cooling from Antarctic sea ice has decreased measurably as well, by 9-14%; this despite the fact that Antarctic sea ice extent only began to decline around 2016, after decades of relative stability. The Arctic has warmed 3-4 times faster than the rest of the planet; and Antarctica around twice as fast. This decline in sea ice extent and reflectivity in both polar regions may be part of the reason for this more rapid polar warming, in a feedback much stronger than predicted by global climate models.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL109608