December 12, 2013
ESA CryoSat Mission Confirms Antarctic Ice Loss Is On The Rise
Alan McStravick for redOrbit.com - Your Universe Online
With news out of San Francisco this week, at the autumn meeting of the American Geophysical Union (AGU), we learned scientists have incorrectly estimated the amount of ice being lost on the polar continent of Antarctica. This environmental faux pas directly affects the estimates on global sea level rise as well.
The corrected figures, a result of three years of observation by the ESA's CryoSat mission, show that the West Antarctic Ice Sheet is experiencing a loss of nearly 100 cubic miles of ice yearly. This figure is considerably more than the previous estimate which offered a related estimate of global sea level rise of over 1/10th of an inch each year between the years of 2005 and 2010. The corrected figure increases global sea level rise 15 percent above what was previously believed.
“We find that ice thinning continues to be most pronounced along fast-flowing ice streams of this sector and their tributaries, with thinning rates of between 4–8 m per year near to the grounding lines – where the ice streams lift up off the land and begin to float out over the ocean – of the Pine Island, Thwaites and Smith Glaciers,” said Dr Malcolm McMillan from the University of Leeds, UK.
Ice losses in West Antarctica stem from glaciers flowing off the continental shelf and into the Amundsen Sea. It is the melting of these ice sheets, and those on Greenland, that are recognized as the major contributor to sea level rise.
The team was able to arrive at these new figures thanks to the CryoSat mission, which was launched in 2010. It possesses a radar altimeter that is able to penetrate cloud cover and the dark of prolonged nights, both of which are characteristics of the southernmost continent.
Additionally, CryoSat is able to measure the surface height variation of ice and is able to do so in high-resolution. This, says the team, allowed them to more accurately calculate the volume of the ice observed.
The study, led by Professor Andrew Shepherd of the University of Leeds, claims the increased figures related to ice loss could very well be due to an increase in the thinning of the ice. However, they believe it is also likely CryoSat has enabled them to observe previously unseen terrain.
“Thanks to its novel instrument design and to its near-polar orbit, CryoSat allows us to survey coastal and high-latitude regions of Antarctica that were beyond the capability of previous altimeter missions, and it seems that these regions are crucial for determining the overall imbalance,” Shepherd said.
CryoSat is the next generation of Antarctic altimeter observation, building on the previous 20 years of observation by the ERS-1, ERS-2 and Envisat satellites. The ESA is already developing future satellites, as part of their Copernicus program, aimed at continual monitoring of changes in the polar ice sheets over the coming decades. The Sentinel-1 and Sentinel-3 satellite series are scheduled to launch next year.
The AGU annual fall meeting is attended annually by more than 20,000 Earth and space scientists, educators and students.