Mark Serreze: Arctic Amplification and Changing Precipitation
Geography Distinguished Professor Mark Serreze and colleagues published a in the journal “The Cryosphere” on Arctic Amplification (AA) - the much stronger observed warming of the Arctic compared to the globe as a whole. Serreze concludes that one of the most important processes driving Arctic Amplification is summertime loss of the Arctic’s sea ice cover. More melt of the sea ice cover in summer exposes ever larger dark open water areas which pick up the sun’s energy. As summer fades into winter and the sun sets in the Arctic, the extra heat gained by the ocean is released upward to the atmosphere. This is why Arctic Amplification is most strongly expressed in autumn, and along the Russian coast that has seen the largest summer ice losses. These areas have warmed by more than 2K per year, or 8-10 degrees Kelvin over the period 1980-2024 (Figure xx). An important contributor to Arctic Amplification is that the Arctic atmosphere is characterized by a strong temperature inversion, which inhibits mixing, focusing the heating near the surfaces. However, Arctic Amplification is also changing the Arctic atmosphere to make it less stable. Research on Arctic Amplification ties in with research led by former graduate student Zaria Cast in another paper published in “The Cryosphere” on how warming is starting to change the Arctic from a snowfall to a rainfall dominated region. As Arctic temperatures continue to rise, precipitation increases, and more and more of that precipitation falls as snow will fall as rain. It is well known that rain on snow events in the Arctic, which are increasing in frequency, have severe consequences for traditional reindeer herding when hard icy crusts form that inhibit grazing. There are well recorded cases where tens of thousands of reindeer have died following a rain on sow event.
Figure: The change in Arctic temperatures in degrees (Kelvin) per year during autumn over the period 1980 through 2024.
