Disappearing Sea Ice

“Sea ice has become the canary in the coal mine of global climate change.”

The news is sobering.  Arctic summer sea ice is receding faster than previously projected and is expected to virtually disappear before mid-century. Sea ice in the Arctic has decreased dramatically since the late 1970s, particularly in summer and autumn. Ice thickness decreased by more than 50% from 1958-1976 to 2003-2008, and the percentage of the March ice cover made up of thicker ice (ice that has survived a summer melt season) decreased from 75% in the mid-1980s to 45% in 2011. Ice loss increases Arctic warming by replacing white, reflective ice with dark water that absorbs more energy from the sun.

The result drives further warming and more ice melt. (See time lapse video story of sea ice melt https://climate.nasa.gov/vital-signs/arctic-sea-ice/)

Impacts in Alaska?

Dramatic reductions in sea ice are transforming everything from the impacts of storms, to access to subsistence resources and the fate of walrus. Sea ice is a powerful driver of ocean ecosystems and coastal environments.  The impact of changes in sea ice ripple through the entire marine ecosystem, as well as opening the area to greater ship access and increasing coastal erosion.

Changes in sea ice alone are having profound effects on sea surface temperatures and on the totality of the marine ecosystem.  The underside of sea ice supports large colonies of algae.  When the ice melts in the spring, algae falls into the water column, providing nutrients that drive primary production – phytoplankton, zooplankton – the food that in turn supports fish, seals, whales and walruses.

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