Polar Ice-Caps & Sea-Level Rise

Scott Church
Climate Change 2001, Chap. 11: Changes in Sea-Level
Intergovernmental Panel on Climate Change, Working Group I
This is the chapter from the IPCC’s year 2001 Third Annual Report (TAR) that dealt with sea-level rise due to global warming. It is one of the most thorough compilations available regarding the state of knowledge on this subject as of that year. Apart from a few recent advances regarding polar ice-caps, most of its contents are still current.
Measurements of Time-Variable Gravity Show Mass Loss in Antarctica
Velicgna, I. and J. Wahr. 2006. Science, 311, (5768), pp. 1754 – 1756. DOI: 10.1126/science.1123785
This study used data from the Gravity Recovery and Climate Experiment (GRACE) satellites to determine mass variations of the Antarctic ice sheet during 2002–2005. The result is significant because the GRACE platform detects variations in total mass directly via their gravitational impacts, and as such its measurements are not subject to any of the noise sources or incomplete coverage area problems that affect most other studies. Velicgna and Wahr found a significant net mass loss for the Antarctic region which translates directly into rising sea-levels. Their results are in good agreement with those obtained by most other studies of the region.
Antarctic Climate Change During the Last 50 Years
Turner et al. 2005. Int. J. Climatol. 25, pp. 279–294. DOI: 10.1002/joc.1130
This study from a team led by John Turner of the British Antarctic Survey used data from the Reference Antarctic Data for Environmental Research (READER) project to investigate trends in monthly mean near-surface temperature, mean sea-level pressure (MSLP) and wind speed for the Antarctic continent over the last 50 years. The data came from a network of 19 stations at different locations where long-term records are available. They found major increases in warming during this period on the Antarctic Peninsula and slight cooling around the continental rim, consistent with activity of the Southern Hemisphere annular mode (SAM), which has been shifting Antarctic surface warming toward the Peninsula in recent decades.
Recent dramatic thinning of largest West Antarctic ice stream triggered by oceans
Payne et al. 2004. Geophys. Res. Lett. 31, (L23401), DOI: 10.1029/2004GL021284
A growing body of evidence suggests that the Pine Island Glacier, which is the primary drainage path for the West Antarctic Ice Sheet (WAIS) is changing on decadal or shorter timescales. This model-based study suggests that these changes are being driven by the surrounding ocean. A warmer ocean can contribute to melting on the underside of glaciers at their point of contact with the ground (or basal melting). This in turn can lubricate the glacier’s underside and speed up its rate of movement and eventually make it unstable. As global warming is known to be affecting the oceans here and around the world, these results add to the body of evidence suggesting that instability of the WAIS and other ice sheets around the world may be accelerating in unexpected ways. If so, this raises the possibility of sudden and possibly even catastrophic sea-level changes during the coming century that are not on the horizon today.
Antarctic Heating and Cooling Trends
NASA Goddard Institute for Space Studies
These links show color plots of surface temperature trends for the Antarctic continent from 1982 to 2004 as measured by the Advanced Very High Resolution Radiometer (AVHRR) package on NOAA’s Polar Orbiting Environmental Satellite (POES) series and supplemented with other in-situ surface temperature measurements. They reflect a warming in the surrounding ocean and coastal rim and a cooling of the Antarctic interior, both of which are expected from the net impacts of global warming, ozone depletion and resulting changes in the Southern Annular Mode (SAM) and oceanic currents circumventing the South Pole. One of these impacts that is likely contributing to the interior cooling is an increase in snowfall due to rising oceanic temperatures and atmospheric moisture content in the surrounding ocean.
The Greenland Ice


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