Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review
Other literature type
- Publisher: Copernicus Gesellschaft Mbh
Sea ice is the central component and most sensitive indicator of the Arctic
climate system. Both the depletion and areal decline of the Arctic sea ice cover,
observed since the 1970s, have accelerated since the millennium.
While the relationship of global warming to sea ice reduction is evident and underpinned
statistically, it is the connecting mechanisms that are
explored in detail in this review.
Sea ice erodes both from the top and the bottom.
Atmospheric, oceanic and sea ice processes interact in non-linear ways on
various scales. Feedback mechanisms lead to an Arctic amplification of the
global warming system: the amplification is both supported by the ice
depletion and, at the same time, accelerates ice reduction. Knowledge
of the mechanisms of sea ice decline grew during the
1990s and deepened when the acceleration became clear in the early
2000s. Record minimum summer sea ice extents in 2002, 2005, 2007 and 2012
provide additional information on the mechanisms.
This article reviews recent progress in understanding the sea ice decline. Processes are
revisited from atmospheric, oceanic and sea ice perspectives. There is
strong evidence that decisive atmospheric changes are the major driver of
sea ice change. Feedbacks due to reduced ice concentration, surface albedo,
and ice thickness allow for additional local atmospheric and oceanic influences and
self-supporting feedbacks. Large-scale ocean influences on Arctic Ocean
hydrology and circulation are highly evident. Northward heat fluxes in the
ocean are clearly impacting the ice margins, especially in the Atlantic
sector of the Arctic. There is little indication of a direct and decisive
influence of the warming ocean on the overall sea ice cover, due to an
isolating layer of cold and fresh water underneath the sea ice.