Global warming could increase sea levels by 21 feet, scientists warn

posted by DAISY in Climate Change

Rising sea levels due to global warming could be much higher than previously thought, swamping coastal areas such as southern Florida and putting Washington D.C. under water, according to a new study.

If the West Antarctic Ice Sheet were to collapse, current estimates by the Intergovernmental Panel on Climate Change put sea levels at 16.5 feet. However, researchers from the University of Oregon and the University of Toronto have predicted that the sea level rise could reach 21 feet. In Europe, sea levels could rise by 18 feet.

The report, which will be published in Science on Friday, explains that when the original estimate was made, several significant factors were not taken into account, including the gravitational pull of the huge ice sheet on the surrounding water, which would be lost if the ice were to melt.

“A study was done more than 30 years ago pointing out this gravitational effect, but for some reason it became virtually ignored,” said Peter Clark, a professor of geosciences at Oregon State University. “People forgot about it when developing their sea level projections for the future.”

The melting of the ice sheet would have other effects too. According to the study, the removal of the weight of the ice would shift the rotational axis of the Earth by about a third of a mile, which would also alter sea levels.

With all this taken into account, sea levels would decrease around Antarctica, while rising in the Northern Hemisphere.

“If this did happen, there would also be many other impacts that go far beyond sea level increase, including much higher rates of coastal erosion, greater damage from major storm events, problems with ground water salinization, and other issues,” said Clark.

“And there could be correlated impacts on other glaciers and ice sheets in coastal areas that could tend to destabilize them as well.”

It is not yet clear how long it may take for the West Antarctic Ice Sheet to melt completely.

"These same effects apply to any amount of melting that may occur from West Antarctica,” Clark said. “So many coastal areas need to plan for greater sea level rise than they may have expected.”

Meanwhile there is also concern over the fate of Antarctica's marine life, as global warming means predators from warmer seas are moving into Antarctic waters, threatening established ecosystems.

See images and video showing effects of rising sea levels here.
Source: University of Oregon