Harveylives
11-15-2003, 01:07 PM
New research reveals 50-year sustained Antarctic ice decline
Agence France-Presse
Sydney, November 14
This 1993 photo shows a glaciologist removing a core ice to study the chemical make-up of its body dating back to 1840, and to provide the first long-term record of sustained decline in Antarctic ice (Photo: AFP)
Australian researchers reported on Friday a significant and steady reduction in Antarctic sea ice over the past 50 years in a development with 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 per cent loss of sea ice around the Antarctica 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.
A glaciologist (far left) walks past research equipment in Law Dome Camp, Antartica (Photo: AFP)
"This latest research, from the top 150 metres of the Law Dome ice core extends our knowledge back to 1840 and explains why satellite trends are confusing.
"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 a crucial role in ocean circulation, heat exchange and global climate control.
There has been growing 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 low lying coastal areas and ocean atolls.
For Curran's study, the results of which were published on Friday in the journal Science, scientists measured levels of Methane Sulphonic Acid -- an atmospheric aerosol produced as a result of phytoplankton activity at the surface of ocean waters -- in the 160 years of core samples.
Phytoplankton are single-cell plants that form a major food source for species such as krill and whales and their activity in the Southern Ocean is closely linked to sea ice distribution.
"What we can say with data obtained from the ice core is that between 1841 and 1950 there was very little change, but there is a marked decline in sea ice distribution since 1950 of around 20 per cent," Curran said.
Scientists are still trying to determine whether the decline was a result of climate change or part of a natural cycle, he said.
Agence France-Presse
Sydney, November 14
This 1993 photo shows a glaciologist removing a core ice to study the chemical make-up of its body dating back to 1840, and to provide the first long-term record of sustained decline in Antarctic ice (Photo: AFP)
Australian researchers reported on Friday a significant and steady reduction in Antarctic sea ice over the past 50 years in a development with 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 per cent loss of sea ice around the Antarctica 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.
A glaciologist (far left) walks past research equipment in Law Dome Camp, Antartica (Photo: AFP)
"This latest research, from the top 150 metres of the Law Dome ice core extends our knowledge back to 1840 and explains why satellite trends are confusing.
"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 a crucial role in ocean circulation, heat exchange and global climate control.
There has been growing 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 low lying coastal areas and ocean atolls.
For Curran's study, the results of which were published on Friday in the journal Science, scientists measured levels of Methane Sulphonic Acid -- an atmospheric aerosol produced as a result of phytoplankton activity at the surface of ocean waters -- in the 160 years of core samples.
Phytoplankton are single-cell plants that form a major food source for species such as krill and whales and their activity in the Southern Ocean is closely linked to sea ice distribution.
"What we can say with data obtained from the ice core is that between 1841 and 1950 there was very little change, but there is a marked decline in sea ice distribution since 1950 of around 20 per cent," Curran said.
Scientists are still trying to determine whether the decline was a result of climate change or part of a natural cycle, he said.