Global representation of trends and variability in ice and water
mass recovered by GRACE over 15 years. The top figure, which shows trend
maps over Antarctica, Greenland and part of the Arctic, represent changes in
ice mass. The middle trend map mainly represents changes in the terrestrial
water storage, as well as large trends related to continental rebound after glacier
ice-melts over continental areas, such as Alaska, Patagonia and the Canadian Arctic.
The trends of the terrestrial water storage are partially related floods and droughts,
but also reflect, for example, long term changes in groundwater depletion by human
activity. The bottom figure shows variability in the ocean bottom pressure and are
particularly relevant for understanding these effects in in the difficult to observed
southern oceans and the Arctic Ocean. For the first two, the red represents mass
loss and blue represents mass gain. In last figure, the color scales represent
variability, with the highest variability shown in red.