Sea Level Climbs Three Millimetres Per Year

Over the past 12 years sea levels have risen by three millimetres per year, in the 40 years before it was only two millimetres per year. The reason for this is rising world temperatures. NASA-researchers report they can measure oceanic levels precisely by using satellites.

According to scientists the sea-level rise jeopardizes many densely populated coastal regions in the long-term, as it could significantly escalate. “We estimate about 100 million people are directly affected if the sea level rises one metre”, said Waleed Abdalati from the Goddard Space Flight Centre of NASA in Greenbelt.

Abdalati and his research colleagues measured the water level changes in the Oceans with satellites and could extrapolate eventual up- and down-movements of the mainland.

The result: In the recent 50 years the sea level increased annually by 1.8 millimetres, which is in accordance with the results of former analyses by different scientists.

Another reason for the rise of the sea level was melting ice. Satellites help to define precisely the extent of ice descending or growing, explained the scientists.

According to Eric Rignot, scientific executive of Radar Analyses at NASA’s Jet Propulsion Laboratory (JPL), modifications of ice are probably the most important factor influencing the sea level. The ice is expected to shrink much more rapidly than previously assumed.

But thawing ice doesn’t automatically mean a rise of the sea level. Particularly in the Arctic the ice is heavily declining. But as long as the ice is swimming on the water, the sea level is not changed.

Researchers from the Institute for Climate Effects in Potsdam, Germany, think that changes in the ocean streams have more dramatic consequences on the water levels than melting ice.

They analyzed a possible breakdown of the ocean circulation and found out that the sea level would rise by a metre on the coasts of the North Atlantic while it would sink in the South Atlantic.

The increase rate would accede to up to 25 millimetres per year, much more than the three millimetres investigated by NASA.

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