London: By the dawn of this millennium, the West Antarctic ice sheet is likely to collapse and the global sea level may rise by nearly four meters, suggests a new study.
Researchers have said that the impact of rising CO2 levels in the Earth``s atmosphere will cause unstoppable effects to the climate for at least the next 1000 years.
The study, which is based on best-case, ``zero-emissions`` scenarios, is the first full climate model simulation to make predictions out to 1000 years from now.
"We created ``what if`` scenarios," said Shawn Marshall of the University of Calgary, as saying.
"What if we completely stopped using fossil fuels and put no more CO2 in the atmosphere? How long would it then take to reverse current climate change trends and will things first become worse?" he said.
The research team explored zero-emissions scenarios beginning in 2010 and in 2100.
The Northern Hemisphere fares better than the south in the computer simulations, with patterns of climate change reversing within the 1000-year timeframe in places like Canada.
At the same time parts of North Africa experience desertification as land dries out by up to 30 percent, and ocean warming of up to five degree Celsius off of Antarctica is likely to trigger widespread collapse of the West Antarctic ice sheet, a region the size of the Canadian prairies.
According to the researchers one reason for the variability between the North and South is the slow movement of ocean water from the North Atlantic into the South Atlantic.
"The global ocean and parts of the Southern Hemisphere have much more inertia, such that change occurs more slowly.
"The inertia in intermediate and deep ocean currents driving into the Southern Atlantic means those oceans are only now beginning to warm as a result of CO2 emissions from the last century. The simulation showed that warming will continue rather than stop or reverse on the 1000-year time scale," said Marshall.
Wind currents in the Southern Hemisphere may also have an impact. Marshall said that winds in the global south tend to strengthen and stay strong without reversing.
"This increases the mixing in the ocean, bringing more heat from the atmosphere down and warming the ocean,” he added.
The study was published in the journal Nature Geoscience.