We are very pleased to welcome Dr. Hailong Wang of the Pacific Northwest National Laboratory as part of the CLASP Seminar Series.

Dr. Wang will give a lecture titled "Understanding causes and effects of surface albedo reduction in the Arctic."

Abstract: Since the early 1980s, the Arctic has warmed 2-3 times faster than the global mean, a feature often called Arctic amplification. As the Arctic warms, the retreat of snow and ice together with the associated feedbacks is known to be an important reason for Arctic amplification. According to our feedback estimates from historical climate model simulations and reanalysis data sets, much of the Arctic amplification of warming can be attributed to the surface albedo feedback. Satellite observations reveal a 1% per decade absolute reduction in the Arctic mean surface albedo in spring and summer during 1982-2014. We used results from a global climate model and multiple reanalysis data sets to unravel the causes of this decreasing trend. We found that reductions of terrestrial snow cover, snow cover fraction over sea ice, and sea ice extent appear to contribute equally to the Arctic albedo decline. Further analysis of the global model results showed that the decrease in snow cover fraction is primarily driven by the increase in surface air temperature, followed by declining snowfall. Although the total precipitation has increased as the Arctic warms in the recent decades, Arctic snowfall has decreased substantially in all the analyzed data sets. It is well known that the presence of light-absorbing soot can significantly darken the snow and ice surface, but soot has been decreasing in the past decades over the Arctic, indicating that soot heating has not been the driver of changes in the Arctic snow cover, ice cover, and surface albedo since the 1980s.

Please join us!