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Sea Level Could Rise from 0.75 to 1.9 Meters This Century

Sea Level Could Rise from 0.75 to 1.9 Meters This Century

A new scientific study warns that sea level could rise much faster than previously expected.

By the year 2100, global sea level could rise between 75 and 190 centimetres, according to a paper published in the Proceedings of the National Academy of Sciences.

The authors, Martin Vermeer of Helsinki University of Technology in Finland and Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research in Germany, based their analysis on measurements of sea level and temperature taken over the past 130 years. In those data they identified a strong link between the rate of sea level rise and global temperature.

"Since 1990 sea level has been rising at 3.4 millimetres per year, twice as fast as on average over the 20th Century," says Stefan Rahmstorf. Even if that rate just remained steady, this would already lead to 34 centimetres rise in the 21st century. "But the data show us clearly: the warmer it gets, the faster sea level rises. If we want to prevent a galloping sea level rise, we should stop global warming as soon as possible," adds Rahmstorf.

The link between the rate of sea level rise and global temperature was originally proposed by Rahmstorf in an article in the journal Science in 2007.

The new study refines this idea. It adds a second term to the equation in order to capture the short-term response of sea level, leading to greater physical realism as well as a much greater precision. Vermeer and Rahmstorf also added the latest data sets, including satellite measurements up to 2008 and a correction for water storage in man-made reservoirs, which overall lowers global sea level by 3 centimetres.

Their results show that even for a relatively low greenhouse gas emissions scenario with just 2 degrees Celsius warming over the 21st century, sea level is likely to rise by more than one meter.

Their highest scenario, with over 4 degrees Celsius warming over the 21st century, would lead to over 1.4 meters of sea level rise by 2100. When the full set of emissions scenarios and estimated uncertainties are considered, waters may rise by anything between 75 centimetres and 1.9 metres by the year 2100 - consistent with another recent estimate of an upper limit of 2 metres, based on consideration of ice sheet dynamics.


"Inundated areas (blue) in lower Manhattan (New York) in a statistically typical one-hundred year storm event based on the present sea level. A sea-level rise of 1 metre would result in storm surges of this height approximately every four years. (Credit: Source: Rosenzweig and Solecki, 2001; data based on USGS, U.S. Army Corps of Engineers, Marquise McGraw, NASA GISS)"

Source: Potsdam Institute for Climate Impact Research

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