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Climate science: More variable sea levels in a warmer ocean

Communications Earth&Environment

August 21, 2020

Seasonal to interannual sea level variability could increase by 4 to 10% in locations around the globe as the upper oceans warm by 2 ºC by the end of the century — regardless of whether ocean temperatures become more variable — suggests a paper published in Communications Earth & Environment.

High variability in coastal sea levels, in addition to rising mean sea levels, is already leading to flooding and erosion. Sea level rise is partly caused by seawater expanding as it warms. This thermal expansion is stronger at higher water temperatures. This means that a fluctuation in temperature of, for example, 5 ºC between seasons will lead to a larger difference in seawater volume for future warmer oceans.

Matthew Widlansky and colleagues used an ensemble of climate model simulations to calculate the effect of stronger thermal expansion at late-21st century ocean temperatures for locations around the world. They find that the tendency for increased sea level variability is 3 to 4% in Jakarta, Mumbai, Manila and Lagos, and 8% in New York City. Variability increases along many coasts, especially at higher latitudes where ocean warming is expected to reach down to greater depths.

doi: 10.1038/s43247-020-0008-8

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