Author: Carolyn Gramling / Source: Science News
Sea level rise over the next century won’t get a feared boost from Antarctic ice cliffs crumbling into the ocean like dominoes, a new study suggests.
The finding, published February 7 in Nature, is based on a new statistical analysis showing that such a rapid collapse of marine ice cliffs in Antarctica was extremely unlikely to have happened in the past, even during some of Earth’s warmest episodes over the last 3 million years.
The study, by climate scientist Tamsin Edwards of King’s College London and colleagues, counters a controversial hypothesis that suggests that rising greenhouse gas emissions could destabilize those cliffs and help send sea levels surging by over 2.1 meters by 2100. That figure is nearly double some sea level rise projections for the end of the century.
How quickly human-caused global warming is causing the great ice sheets covering Greenland and Antarctica to melt into the sea is one of the most urgent questions related to future sea level rise.
Some scientists fear that melting could speed up dramatically sometime in the future, thanks to a possible feedback loop known as marine ice-cliff instability, or MICI. The hypothesis was described by geoscientist Robert DeConto of the University of Massachusetts Amherst and paleoclimatologist David Pollard of Penn State in a 2016 study in Nature. Using computer simulations of the mechanical and structural properties of ice, the researchers suggested that ice cliffs at the edges of glaciers that jut into the sea are a dramatically underestimated source of future sea level rise (SN: 4/30/16, p. 13).
“Ice that flows into the ocean essentially always ends in a cliff,” DeConto says. “Basic physics tells us that very tall cliffs, extending 100 meters or more above the water surface, will begin to produce stresses in the ice that can exceed its strength.” When that happens, the ice breaks, or calves, and giant blocks of ice tumble into the sea. The collapse of such cliffs would then create new cliffs behind them that would tumble as well, in a kind of domino effect.
…
The post Collapsing ice cliffs may not contribute to sea level rise appeared first on FeedBox.