Keywords: Northern Hemisphere Sea Ice Extent Anomalies.png Trends in Extent Northern Hemisphere Arctic Sea Ice Ice extent anomalies are plotted as a time series of percent differences between the total extent for the month in question and the mean for that month where the mean is based on the January 1979 - December 2000 portion of the data set The trend in percent change per decade is obtained using least squares regression and a 95 confidence interval for the resulting slope is given http //nsidc org/data/seaice_index/n_plot html 2008-05 National Snow and Ice Data Center thumb left graph PD-USGov Regression analysis Statistics for Arctic sea ice melting |