11 August 2006
Antarctic Snowfall Snafu Derails Climate Models
by Kate Melville
An improved method of measuring Antarctic snowfall has revealed that previous records showing an increase in precipitation are not accurate, even over a half-century. In the August 10 edition of Science magazine, researchers explain that their analysis of ice cores and snow pits revealed that precipitation levels in the Antarctic have in fact remained steady. The upshot of the study is that models assessing climate-change may need to be revised, as they can no longer be deemed accurate.
The multinational Antarctic team comprised 16 researchers who wanted to amass snowfall data going back 50 years to the International Geophysical Year (IGY). The data taken from the IGY is regarded as the first real study of the Antarctic, which has been ongoing ever since. This time around, however, the team found that their data contradicted computer models used to calculate global climate change, where most predict an increase in precipitation as atmospheric temperatures increase.
"There were no statistically significant trends in snowfall accumulation over the past five decades, including recent years for which global mean temperatures have been warmest," said lead author Andrew Monaghan, a research associate with Ohio State University's Byrd Polar Research Center.
During the expedition, the team used data from ice core samples, networks of snow stakes and meteorological observations. Not satisfied with this data alone, the team also included ice core records from the International Trans-Antarctic Scientific Expedition (ITASE), another multinational research program that began in 1990 in order to reconstruct the continent's climate history. The latest team's voracious accumulation of data coupled with a thorough analysis provides the most accurate study to-date of the West Antarctic Ice Sheet (WAIS) and the thicker East Antarctic Ice Sheet (EAIS).
Recent observations of the WAIS, a marine ice sheet with a base below sea level, show that vast quantities of ice are melting at a faster rate than previously recorded. Many observers consider this and an increase in calving icebergs along the Antarctic's margins to be evidence of global warming. The team's findings also counter climate-change skeptics who consider a thickening of Antarctica's enormous ice sheets has stemmed the gradual rise in global sea levels.
The new study shows that current climate-change models need to be revamped if scientists are to have a more accurate representation of Antarctic weather patterns. "The year-to-year and decadal variability of the snowfall is so large that it makes it nearly impossible to distinguish trends that might be related to climate change from even a 50-year record," said Monaghan.
Source: National Science Foundation