25 years of satellite data shows global sea level surging at faster rate

In the paper, a team of climate researchers shows evidence that global sea levels are rising at an accelerating rate. If the rate of change continues it could cause massive trouble for coastal cities.

Feb 14, 2018 09:45 IST
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As per a new assessment based on 25 years of satellite data, the global sea level is not rising at a steady rate; it is accelerating a little every year.

The study was done by researchers at the University of Colorado at Boulder in the US which was published in the journal PNAS.

Highlights of the study

The study measured that the sea level rate is increasing by about 0.08 millimeters per year (mm/year).
That could mean an annual rate of sea level rise of 10 mm/year, or even more, by 2100.

This acceleration is mainly driven by rapid melting in Antarctica and Greenland which has the potential to double the total sea level rise by 2100 as compared to projections that assume a constant rate to more than 60 cm instead of about 30.

The study highlighted that if the oceans keep on to growing at this pace, sea level will rise 65cm by 2100. Hence, it could be enough to cause noteworthy trouble for coastal cities.

Why this acceleration?

In Earth’s atmosphere, growing concentrations of greenhouse gases increase the temperature of air and water, which causes sea level to rise in two ways.

First, warmer water expands, and this “thermal expansion” of the oceans has contributed about half of the 7cm of global mean sea level rise over the last two and half decades.
Second, melting land ice flows into the ocean, also increasing sea level across the globe.

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How the findings reported?

These increases were measured using satellite altimeter measurements since 1992, including the US/European TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 satellite missions.

La NINA and El NINO and (the opposing phases of the El Nino Southern Oscillation, or ENSO) influence ocean temperature and global precipitation patterns.

The study group had used climate models to account for the volcanic effects and other datasets to determine the ENSO effects, ultimately uncovering the underlying sea-level rate and acceleration over the last quarter century.

They also used data from the Grace Satellite gravity mission to determine that the acceleration is largely being driven by melting ice in Greenland and Antarctica.

The study says that the satellite records can play the important role in validating climate model projections.
It also shows how climate models are important in interpreting satellite records, such as in this study where it allows the study group to estimate the background effects of the 1991 eruption of Mount Pinatubo on global sea level.


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