Coastal challengesWarming Oceans Could Drive Antarctic Ice Sheet Collapse, Sea Level Rise
In the U.S., four out of ten people live in populous coastal areas, making them vulnerable to the effects of rising seas. Seventy percent of the world’s largest cities are located near a coast. Globally, by 2010, seas had already risen about 10 inches above their average levels in pre-industrial times. A new study suggests the Western Antarctic Ice Sheet is less stable than researchers once thought, and that its collapse would accelerate sea level rise.
A new study suggests the Western Antarctic Ice Sheet is less stable than researchers once thought. As in the past, its collapse in the future is likely.
The finding is based in part on the results of a paper published in Nature, co-led by University of Wisconsin–Madison atmospheric scientist Feng He and Oregon State University’s Peter Clark, which looks back at the last two time periods in which the planet transitioned from a glacial state, when ice sheets covered large swaths of the globe, into an interglacial state, such as the one we are in now.
The goal of the study, he says, was to better understand what contributes to rising sea levels. This has challenged researchers because of the large amount of uncertainty involved in understanding the contributions made by the melting of the Greenland and Antarctic ice sheets.
“Essentially, we just don’t know how fast they are going to melt, whether the marine-based Antarctic ice sheet will collapse, or how quickly it will happen – whether it’s 100 years or 1,000 years,” says He, associate scientist in the Center for Climatic Research at the Nelson Institute for Environmental Studies. “By 2200, there is a possibility of 7.5-meter sea level rise when accounting for the instability of the western and eastern Antarctic Ice Sheet.”
Wisconsin says that overall, the study found that warming below the surface of the planet’s oceans is a significant contributor to ice sheet melt, particularly in the Antarctic, where a large portion of the ice sheet exists under the water.
During the last two transitions from glacial into interglacial periods, that warming was largely driven by the disruption of a process known as the Atlantic Meridional Overturning Circulation (AMOC), akin to an oceanic conveyor belt that carries warm waters northward and cold waters south.
Sub-surface warming, also referred to as oceanic forcing, was likely responsible for the collapse of the Western Antarctic Ice sheet during Earth’s last interglacial period going back 125,000 years, which led to three meters of sea level rise. Overall, seas rose by up to nine meters, or nearly 30 feet, during the last interglacial period.
“Even right now, observations show that 50 percent of the mass loss from the Antarctic Ice Sheet is from subsurface ocean forcing,” he says.
