Changes... in Alaska


You found / read an article this week about President Obama's visit to Alaska.

Water exercise

One way that we'll put the changes in Alaska into context is to look at another kind of "rate of change": This time, the rate of change of "water storage".

The graphs below are from the GRACE satellites (a joint operation of NASA and the German space agency). They use gravity to measure changes in water stored (WS or TWS="total water storage") over the years.

The satellite data has been gridded, such that one graph represents the change in water storage in a 1${}^o$ latitude by 1${}^o$ longitude area (a "pixel" on the Google Earch image we'll see next week). A "1 cm" increase means that the change in gravity was the same as adding 1 cm of water over the whole 1${}^o$ by 1${}^o$ area. The satellite can't tell if the water stored is in the soil, in rivers and lakes, or in sub-surface aquifers (reservoirs) of water.

Here's an archive of trends in TWS for a variety of locations in the world

Image credits: NBC News