Monitoring and Observations
Changes in sea ice conditions are best demonstrated by the rate of melting over time. A composite record of Arctic ice demonstrates that the floes’ retreat began around 1900, experiencing more rapid melting beginning within the past 50 years. Satellite study of sea ice began in 1979, and became a much more reliable measure of ice melt and polar climate change. In comparison to the extended record, the sea-ice extent in the polar region by September 2007 was only half the recorded mass that had been estimated to exist within the 1950-1970 period.
The volume of ice hit an all-time low in September of 2012, when the ice was determined to cover only 24% of the Arctic Ocean, offsetting the previous low of 29% in 2007. Future predictions cast that summer sea ice might disappear altogether as soon as 2020. During the warmest years, like the winter of 2005-2006, sea ice is observed to reach a winter maximum extent that is smaller than in the years before or after. The summer minimum Arctic ice extent for 2010 was the third lowest over the period of satellite observations of the polar ice.
Read more about this topic: Sea Ice
Famous quotes containing the word observations:
“The natural historian is not a fisherman who prays for cloudy days and good luck merely; but as fishing has been styled “a contemplative man’s recreation,” introducing him profitably to woods and water, so the fruit of the naturalist’s observations is not in new genera or species, but in new contemplations still, and science is only a more contemplative man’s recreation.”
—Henry David Thoreau (1817–1862)