In Is Antarctica Melting?, NASA reports that the mass of ice in Antarctica has been declining by around a hundred cubic kilometers (24 cubic miles) annually since 2002. Furthermore, the rate at which the continent is losing ice is accelerating.

"The important message is that it is not a linear trend. A linear trend means you have the same mass loss every year. The fact that it’s above linear, this is the important idea, that ice loss is increasing with time," says Isabella Velicogna of NASA's Jet Propulsion Laboratory and the University of California, Irvine, in the NASA article.  Furthermore, the article emphasizes that this conclusion is supported by multiple threads of evidence.  "It isn't just one type of measurement," says Velicogna. "It's a series of independent measurements that are giving the same results, which makes it more robust."

Online Resources:

•  Is Antarctica Melting?, by Erick Conway, NASA / Jet Propulsion Laboratory, 12 January 2010.
• Stability of Ice Sheet Grounding Lines.  By Richard F. Katz and M. Grae Worster.  In Proceedings of the Royal Society, 13 January 2010.
• High Resolution View of Pine Island Glacier.  NASA Earth Observatory, 16 November 2001.
• From WWF:
  • 2 Degrees is Too Much: Impact of 2 degrees Celsius Global Warming on Antarctic Penguins (PDF, 1.26MB)
  • Antarctic Penguins and Sea Ice (PDF, 1.67KB)
  • Antarctic Climate Change in the 20th and 21st centuries (PDF, 34KB)