Since 1980 scientists have used data from satellite sensors to calculate a daily measure of Arctic sea ice extent. Sea ice extent is calculated as the sum of the areas of sea ice covering the ocean where the ice concentration is greater than 15%. The graph here shows seasonal variations in sea ice extent for 2012, 2013, and the average values for the 1980s. image According to the graph, during which month does sea ice extent usually reach its maximum? During which month does the minimum extent generally occur? What can you infer about the reason for this pattern?Sea ice extent reached its lowest level to date in 2012. About how much less was the minimum extent in 2012 compared with the average minimum for the 1980s? About what percentage of the 1980s average minimum was the 2012 minimum?How does the maximum extent in 2012 compare with the average maximum for the 1980s? About what percentage of the 1980s average maximum was the 2012 maximum?What do the patterns in the maximum and minimum values suggest about how climate change may be affecting sea ice extent?How do the 2013 maximum and minimum values compare with those for 2012? What possible explanation can you suggest for the differences?