Page 377 - Laboratory Manual in Physical Geology
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September 1979 0 500 1000 1500 2000 2500 km
0 500 1000 1500 miles
Russia Arctic
Sea Ice Greenland
Ice Sheet
Alaska
Canada
Canada
September 2012
Russia Arctic
Sea Ice Greenland
Ice Sheet
Alaska
Canada
Canada
FIGURE 13.16 Extent of Arctic Sea Ice: 1979 and 2012. Sea ice covers essentially all of the Arctic Ocean in winter months, but it melts
back to a minimum thickness and extent by the end of summer (September). These NASA satellite images reveal the minimum extent of Arctic
sea ice at times 33 years apart. Dark blue areas are ocean; gray areas are mountain glaciers and the Greenland Ice Sheet. White and light blue
areas are the Arctic sea ice.
Glaciers and the Dynamic Cryosphere ■ 345
