简体中文
A new research by New Zealand scientists out Tuesday shows that global warming could cause sea levels to rise by "tens of meters" in coming centuries if greenhouse gas emissions continue to increase.
Victoria University researchers found the Southern Ocean sea ice belt -- a protective fringe of frozen ocean water around Antarctica's ice sheet -- was susceptible to ocean warming and could affect the stability of the world's largest ice sheet.
The study contributed to a long-standing "ice-age mystery," resolving how exactly the Earth's orbit around the sun contributed to natural ice-age cycles, Dr. Robert McKay said in a statement.
"It sheds new light on how natural climate processes can dramatically amplify ice sheet responses to relatively small changes in energy that were provided by changes in Earth's orbit," said McKay.
"As we have seen repeatedly in geological records, these ice sheets are highly sensitive to changes in the energy they receive, and are capable of driving global sea level changes by many tens of meters."
Current emissions of large quantities of greenhouse gases provided a far greater amount of energy than the orbits alone would, and at an unprecedented rate.
"Changes from global warming and any future reduction of the ice belt may have profound effects on the stability of the giant East Antarctic ice sheet, because its major parts sit below present day sea level and if melted would total more than 20 meters of increased sea level," he said.
The researchers examined iceberg remains from between 2.2 million and 4.3 million years ago in a remote region offshore from the East Antarctic ice sheet, and found that prior to 2.5 million years ago, when atmospheric carbon dioxide levels were at the same high level as today, the East Antarctic ice sheet melt was widespread.
It left the Southern Ocean was too warm to support a large protective sea ice belt during the summer months, and this allowed wind-driven ocean currents to penetrate deep into the south and melt the marine margins of the East Antarctic ice sheets.
Due to these factors, there was strong potential for widespread ice loss and sea level rise worldwide in the coming centuries, unless carbon dioxide levels were significantly reduced, said McKay.
