Sea levels could rise 1.3 to 2 metres by 2100

New studies have been published concluding that sea levels could rise far more rapidly than expected in coming decades. The UN’s climate science body had predicted up to a metre of sea level rise this century. But a new study led by the Potsdam Institute for Climate Impact Research for the first time, combines the two most important estimation methods for future sea level rise and yields a more robust risk range. Sea levels worldwide will likely rise by 50 to 130 centimetres by the end of this century if greenhouse gas emissions are not reduced rapidly. A second study provides the first global analysis of sea level data for the past 3,000 years. It confirms that during the past millennia the sea level has never risen nearly as fast as during the last century. Even if ambitious climate policy follows the 2015 Paris Agreement, sea levels are projected to increase by 20 to 60 centimetres by 2100.

According to a third study, published in the journal Nature, collapsing Antarctic ice sheets are expected to double sea-level rise to two metres by 2100, if carbon emissions are not cut.

Previously, only the passive melting of Antarctic ice by warmer air and seawater was considered, but the new work added active processes, such as the disintegration of huge ice cliffs.

The Guardian quoted Prof Robert DeConto, at the University of Massachusetts Amherst, who led the work: “this [doubling] could spell disaster for many low-lying cities”. He said that if global warming was not halted, the rate of sea-level rise would change from millimetres per year to centimetres a year. “At that point it becomes about retreat [from cities], not engineering of defences.”

“Many coastal cities are growing fast as populations rise, and analysis by World Bank and OECD staff has shown that global flood damage could cost them $1 trillion a year by 2050 unless action is taken. The cities most at risk in richer nations include Miami, Boston and Nagoya, while cities in China, Vietnam, Bangladesh and Ivory Coast are among those most in danger in less wealthy countries.”

“The new research follows other recent studies warning of the possibility of ice sheet collapse in Antarctica and suggesting huge sea-level rises. But the new work suggests that major rises are possible within the lifetimes of today’s children, not over centuries.”

Compiled by Reinhold Pape from press releases. Links: https://www.pik-potsdam.de/news/press-releases/sea-level-rise-too-big-to..., https://www.pik-potsdam.de/news/press-releases/sea-level-rise-past-and-f...