Antarctic Ice Melt

Antarctica is losing ice mass while gaining ice extent. This is a confusing point to some. There are a few keys that can help us understand what this means in the context of global warming.

Land ice is different than sea ice. Antarctica is losing ice as illustrated below in the ice mass chart from the GRACE satellite.

Antarctic Ice Mass Loss [manual update]

Source: http://www.nasa.gov/topics/earth/features/20100108_Is_Antarctica_Melting.html

Antarctic Ice Extent Increase [updates annually]

Source: http://nsidc.org/data/seaice_index/

The sea ice-extent is increasing as expected also. Context is important here. While it is warming in the Southern Hemisphere (SH), there are other things happening as well. It remains cold during winter which allows ice extent to grown each winter. Summers are warmer so ice mass loss results from that.

Warmer oceans increase atmospheric moisture which adds to the ice extent around Antarctica. 

Models and studies hypothesized in the 70's and 80's that this would occur, so the observations are in line with the expectations and the results are reasonable.

So, in SH winter, ice extent can grow more than usual, while in summer the overall observations satellite observations show that ice mass is being lost.

With more snow precipitation in Antarctica one might expect that the ice mass would grow as well, but at this time the ice discharge rates are not showing overall ice mass increase. A warmer world seems to translate to more snow but faster loss of that snow in the summer.

The Arctic, in the Northern Hemisphere (NH) acts in the opposite direction regarding ice extent, and is also losing ice mass. The main reason that the NH is not gaining ice extent like Antarctica is the Northern or Polar Amplification Effect. This is due to the fact that the NH is mostly land, while the SH is mostly water and ice. So the two hemispheres behave quite differently.

Arctic Ice Extent [updates annually]

Source: http://nsidc.org/data/seaice_index/

Arctic and Antarctic climate:

• http://arctic.atmos.uiuc.edu/cryosphere/
• The Arctic Climate Impact Assessment
• The Arctic Climate Impact Assessment II
• The Arctic Climate Impact Assessment III
• http://www.realclimate.org/index.php/archives/2009/01/state-of-antarctica-red-or-blue
• Will spring 2005 be a bad one for Arctic ozone? () ()
• 2005 Record Arctic Ozone Loss
• Retreating Glacier Fronts on the Antarctic Peninsula over the Past Half-Century () ()
• 650,000 years of greenhouse gas concentrations () ()
• Polar Amplification
• The Greenland Ice
• How much future sea level rise? More evidence from models and ice sheet observations.
• Significant Warming of the Antarctic Winter Troposphere
• More on the Arctic
• Sea level in the Arctic
• Ice Sheets and Sea Level Rise: Model Failure is the Key Issue
• The Copenhagen Consensus
• Is Antarctic climate changing?
• Historical climatology in Greenland
• Not just ice albedo () ()
• Arctic Sea Ice decline in the 21st Century () ()
• Making sense of Greenland's ice
• Arctic sea ice watch
• New rule for high profile papers
• ¿La Antártida está fría? Si, ya lo sabíamos ()
• Sifones, frentes glaciares y la aceleración de los glaciares exteriores de Groenlandia ()
• North Pole notes
• Ice Shelf Instability
• North Pole notes (continued)
• ¿Cuanto subirá el nivel del mar? () ()
• On straw men and Greenland: Tad Pfeffer Responds
• What links the retreat of Jakobshavn Isbrae, Wilkins Ice Shelf and the Petermann Glacier?