UC San Diego

Arctic sea ice loss continues to serve as a strong gauge of climate change. It is the component of the Earth system that is responding most visibly and rapidly to a warming climate. The implications of a shrinking sea ice cover include changes in physical processes like deep water formation and the reflection of solar radiation, and alterations to the way of live for humans and animals that depend on the ice in their daily lives. Here I evaluate long term trends in sea ice coverage in the Greenland Sea and Irminger Basin from 1979 to 2018. While in the Arctic Basin the recession of summer sea ice is more pronounced, it is shown that in the Greenland Sea the declining winter sea ice maximum is more pronounced than the summertime reduction. The strongest signature of this robust trend is the disappearance in 2004 of a sea ice feature called the Odden Ice Tongue that is characterized by local freezing and ice formation and to a lesser extent by the advection of sea ice. A budget constructed from sea ice concentration and velocity estimates from the National Snow and Ice Data Center, and sea ice thickness estimates from the University of Washington’s Pan-Arctic Ice Ocean Modeling and Assimilation System indicates that the area of sea ice transported into the Greenland Sea from the Arctic has gone largely unchanged since measurements began in late 1978. Despite this, the volume of sea ice flowing out of the Arctic has decreased 11% when compared to the 1979-2004 mean due to a significant thinning of sea ice.

In the last 15 years the average winter buildup of sea ice volume in the Greenland Sea is 16% smaller than the same winter accumulation from 1979 to 2004. The volume of sea ice that is advected into the Greenland Sea, from Fram Strait, is approximately twice as large as the change in volume of sea ice in the area over the course of a typical winter, indicating that half of the advected sea ice melts over the course of the winter.