http://rkwok.jpl.nasa.gov/publications/Kwok.2009.GRL.pdf
When you are standing on top of a hill, the only direction you can travel is down. Satellites monitoring the Arctic came on line right at the Arctic ice peak (see the JPL graph above) after the ice age scare of the 1970s. It is therefore not surprising that the amount of ice has diminished through the period of the satellite record.
If you extrapolate linearly you will conclude that the Arctic is going to be ice free in a few years. Based on ICESat data above, you could conclude that the Arctic will be ice free before 2010. Using linear extrapolation, you can also conclude that the Matterhorn reaches sea level a short distance away.
