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Photograph of researchers on the NASA-funded ICESCAPE mission—Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environmen in July 2011.

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Sea Ice and Ocean Summary

Section Coordinator: Andrey Proshutinsky

Woods Hole Oceanographic Institution, MA, USA

November 9, 2011

Sea ice and ocean observations over the past decade (2001-2011) suggest that the Arctic Ocean climate has reached a new state with characteristics different than those observed previously. The new ocean climate is characterized by less sea ice (both extent and thickness) and a warmer and fresher upper ocean than in 1979-2000. The persistence of these changes is having a measureable impact on Arctic marine and terrestrial ecosystems (see the essays on Marine Ecosystems and Terrestrial Ecosystems).

An anticyclonic (clockwise) wind-driven circulation regime has dominated the Arctic Ocean for at least 14 years (1997-2011), in contrast to the typical 5-8 year pattern of anticylonic/cyclonic circulation shifts observed from 1948-1996. Under the recent persistent anticyclonic circulation regime with relatively warm air temperatures (see the essay on Temperature and Clouds) the summer extent of the sea ice cover has been at least 15-20% below the 1979-2000 average. The decline in total sea ice extent has been accompanied by an unprecedented loss of old, thick multiyear ice. Melting sea ice has released additional fresh water into the upper ocean. Influenced by strong anticyclonic winds, fresh water has accumulated in the Beaufort Gyre region, where the fresh water content has increased by approximately 5,000 km3 relative to 1970s climatology. The loss of sea ice has also resulted in the warming of the upper ocean and ocean expansion, leading to an increase in the rate of sea level rise.

In the Bering Sea, aragonite undersaturation, i.e., acidification, throughout the water column is causing seasonal CaCO3 mineral suppression in some areas. The effects of ocean acidification in the Chukchi Sea, induced by the uptake of anthropogenic CO2 over the last century, are amplified by high rates of summertime phytoplankton primary production, which leads to increased seawater pCO2 and decreased pH of sub-surface waters, which become more corrosive to CaCO3.

 

Photograph of researchers on the NASA-funded ICESCAPE mission—Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environmen in July 2011. NASA photograph by Kathryn Hansen. By NASA Goddard Space Flight Center from Greenbelt, MD, USA (Ponds on the Ocean Uploaded by PDTillman) [CC-BY-2.0 (www.creativecommons.org/licenses/by/2.0)], via Wikimedia Commons.