2.6 Old thick sea ice versus young thin sea ice

Due to increasing temperatures ice of all ages declines. Since 1983, 5+ year old ice has declined sharply. The Arctic cover now mainly consists of First year ice which tends to melt rapidly in summer.Newly developed estimates of sea-ice age, basin-scale sea-ice thickness, and sea-ice volume indicate thinning of the ice cover and loss of old ice types.

Figure 9: These images from September 2007 (top, left) and September 2012 (top, right) show the decline of multiyear ice since the previous record minimum extent was set in 2007. The chart at bottom shows the changes in multiyear ice from 1983 to 2012. NSIDC (National Snow and Ice Data Centre)

Find out more:

• AMAP. (2011) Snow, Water, Ice and Permafrost in the Arctic (SWIPA): Climate Change and the Cryosphere. Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway. Xii + 538pp.
• World Bank (2010) Turn down the Heat. Why a 4 degree centigrade warmer world must be avoided.