CryoSat mission measures continuing Arctic sea ice melt

BBC : Since its launch in April 2010, the European Space Agency’s CryoSat-2 satellite has been monitoring the extent and thickness of Earth’s polar ice caps. Although the total area of ice in the Arctic has shrunk noticeably over that time period, it is the loss of volume that concerns researchers most. To calculate the volume, they use radar altimetry to measure the difference in height between the top of the ice and the water level. Knowing that about 7/8 of the ice sits below the water, researchers can then calculate the total ice volume. Because the ice was thinner than usual at the end of the winter this year, the summer volume may hit a record low even if the total ice area does not, according to Andy Shepherd of Leeds University in the UK. How much of the Arctic sea ice melt is due to global warming and how much to natural variation has yet to be determined. Data gathered by CryoSat-2 were presented this week at the European Space Agency’s Living Planet Symposium , which is being held in Edinburgh.