Antarctic winds patterns due to climate change are boosting sea levels
Variations in the patterns of winds around the frozen continent Antarctica, resulting from climate change, may bring rises in global sea levels, researchers say.
The increases could come from rapid melting of the ice sheets on the continent's coastlines as the winds drive warmer water up underneath them, scientists at Australia's ARC Center of Excellence for Climate System Science say.
"When we included projected Antarctic wind shifts in a detailed global ocean model, we found water up to 4 degrees Celsius (7.2 degrees F) warmer than current temperatures rose up to meet the base of the Antarctic ice shelves," lead study author Paul Spence says.
This could present a huge amount of melting just at the point where the ocean ice shelves are grounded on the Antarctic coastline, he says.
The potential huge increase in melting rates of that ice would have a direct impact on sea level increases around the globe, the researchers said.
"When we first saw the results it was quite a shock," says Spence. "It was one of the few cases where I hoped the science was wrong."
Changes in the circulation patterns of Antarctic wind have already been shown to be contributing to Australia's trend toward drier climate, the researchers added.
It may also help explain several unexplained and sudden episodes of global sea level rise in the distant geological past, they said.
Of present concern are estimates that the West Antarctic Ice Sheet by itself could add more than 10 feet to long-term sea level rises globally, say other researchers who've seen the Australian work.
"It is very plausible that the mechanism revealed by this research will push parts of the West Antarctic Ice Sheet beyond a point of no return," says University of Hawaii oceanography Professor Axel Timmerman.
Sea ice around the southern continent currently covers around 6 million square miles of ocean, the U.S. National Snow and Ice Data Center reports.
Portions of East Antarctica are likely to also be impacted by the wind-caused changes in ocean temperatures and current patterns if global warming continues, study co-author Nicolas Jourdain says.
"Dramatic rises in sea level are almost inevitable if we continue to emit greenhouse gases at the current rate," he says.
The use of supercomputers in the new study allowed the modeling of ocean currents and water temperatures at levels of detail not available in previous models, which is why they had not adequately predicted the impact of climate change on Antarctic ice, the researchers noted.