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Global climate change

Instability of Antarctic ice sheet makes future sea level rise estimates more uncertain

By Brett Anderson, AccuWeather senior meteorologist
12/13/2017, 5:09:43 PM

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Projecting how much the world's oceans will rise in the future has been debated for decades with a wide range of estimates.

View of the edge of the Antarctic ice sheet. From NASA

A new study from Rutgers University indicates that scientists may not know how much global sea level will rise by the end of this century until the 2060s.

The study is the first to link global and local sea-level rise projections with simulations of two major mechanisms by which climate change can affect the vast Antarctic ice sheet, according to Rutgers Today.

There are currently a wide range of forecast estimates for global sea level rise by the end of the century. These generally range from 2 feet of global-average sea-level rise to as much as 6 feet by the year 2100. Both of these estimates would still have severe consequences for low-lying coastal areas in the future.

The study is based on an Antarctic ice sheet model that simulates two pathways that can lead to ice sheet instability.

The first pathway is marine ice-sheet instability, which has been studied for many years. The second is marine ice cliff instability, which has only recently been found to be a key contributor to future sea-level change.

The Ross ice shelf in Antarctica.

The interaction between a process called "hydrofracturing" and ice-cliff collapse could cause global sea level to rise much higher (as much as 4-7 feet by the end of the century) than the IPCC's (Intergovernmental Panel on Climate Change) 2013 estimate, which under a high emissions future is likely to be between 2 to 3.5 feet by the year 2100.

Key excerpts from the Rutgers Today report.............

“We’re making progress, but we still don’t know exactly when these processes might kick in, and how fast sea level might rise if they do. The ice shelves are the key. They hold back the flow of Antarctic ice toward the ocean, so we don’t want to lose them. The problem is, they don’t last very long when they are sitting in warm water or if they are covered with summer meltwater, so keeping global temperatures in check is critical,” said Robert M. DeConto of the University of Massachusetts Amherst, a co-author of the study.

“There’s a lot of ambiguity in post-2050 projections of sea-level rise and we may have to live with that for a while,” said Robert E. Kopp, the study’s lead author and a professor in the Department of Earth and Planetary Sciences at Rutgers. “We could end up with 8 feet of sea-level rise in 2100, but we’re not likely to have clear evidence for that by 2050.”

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com


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Global climate change