Australian researchers reported yesterday a significant and steady reduction in Antarctic sea ice over the past 50 years in a development that has implications for understanding global climate change.
Glaciologists from the Australian government's Antarctic Division said their study of cores drilled deep into the ice found a 20 percent loss of sea ice around the Antarctic in the past half-century.
The decline was more pronounced that previously believed and contrasts with satellite observations which have indicated sea ice may have increased in the past 30 years.
Mark Curran, who headed the research team, said their study of the chemical make-up of core ice dating back to 1840 provided the first long-term record of sustained decline in Antarctic ice.
"At first glance this could appear to be at odds with recent opinion that sea ice is not decreasing and may, in fact, be increasing," Curran said in a statement.
"However, what we need to take into account is that until now records have relied, to a large degree, on satellite observations since the 1970s and our work illustrates that 30 years is a very short time over which to draw any conclusions," he said.
"Detection of long-term change is masked by large fluctuations from decade to decade and it is these decadal fluctuations that have produced apparent short-term increases in the satellite data," he said.
Antarctic sea ice forms and decays each year in a cycle that plays an import role in ocean circulation, heat exchange and global climate control.
There has been concern in recent years that global warming caused by man-made "greenhouse gases" was melting the polar ice caps and could lead to the flooding of coastal areas and ocean atolls.
Scientists are still trying to determine whether the decline was a result of climate change or part of a natural cycle, Curran said.