NCAR - Rain, Not Snow; Open Water, Not Ice; An Entirely New Arctic Emerging Rapidly
The effects of global warming in the Arctic are so severe that the region is shifting to a different climate, one characterized less by ice and snow and more by open water and rain, scientists said Monday. Already, they said, sea ice in the Arctic has declined so much that even an extremely cold year would not result in as much ice as was typical decades ago. Two other characteristics of the region’s climate, seasonal air temperatures and the number of days of rain instead of snow, are shifting in the same way, the researchers said.
The Arctic is among the parts of the world most influenced by climate change, with sharply rising temperatures, thawing permafrost and other effects in addition to shrinking sea ice. The study, by Laura Landrum and Marika M. Holland of the National Center for Atmospheric Research in Boulder, Colo., is an effort to put what is occurring in the region in context.
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Using years of observational data from the region and computer models, the researchers found that sea ice is already in a new climate, in effect: The extent of ice in recent years is consistently less than what would be expected in even the worst year for ice in the mid-20th century. Arctic sea ice has declined by about 12 percent per decade since satellite measurements began in the late 1970s, and the 13 lowest sea-ice years have all occurred since 2007. This year is expected to be a record or near-record low for ice extent, which will be determined by the end of this month as the summer melt period ends.
For fall and winter air temperatures and rain vs. snow days, the simulations found that the transition to a new climate is occurring more slowly, with the shift expected to be complete by the middle of the century. Overall, Dr. Landrum said, “We are beginning to get to the point where we can no longer know what to expect.”
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https://www.nytimes.com/2020/09/14/climate/arctic-changing-climate.html