Seas of the world have risen 3 inches since 1992

August 27, 2015 | Environment
Greenland: the glaciers are melting fast | Photo: NASA/NordForsk

The National Aeronautics and Space Administration (NASA) has revealed that the seas of the world have risen three inches (eight centimeters) since 1992. Data suggests that the sea level will likely increase by one meter or more in the next 100-200 years.

The satellite measurements from NASA and its partners concluded that about one-third of sea-level rise is caused by the expansion of warm ocean water, one-third is due to ice loss from the Greenland and Antarctic ice sheets, and the remaining third results from melting mountain glaciers.

"Given what we know now about how the ocean expands as it warms and how ice sheets and glaciers are adding water to the seas, it's pretty certain we are locked into at least 3 feet [0.9 meters] of sea-level rise, and probably more. But we don't know whether it will happen within a century or somewhat longer," explains Steve Nerem, a member of the Sea Level Change Team.

There are multiple regional differences in sea-level rise due to the effects of ocean currents and natural cycles such as the Pacific Decadal Oscillation. But, as these natural cycles wax and wane, they can have major impacts on local coastlines.

"Sea level along the west coast of the United States has actually fallen over the past 20 years because long-term natural cycles there are hiding the impact of global warming," adds Josh Willis, an oceanographer at NASA.

"However, there are signs this pattern is changing. We can expect accelerated rates of sea-level rise along this coast over the next decade as the region recovers from its temporary sea level 'deficit.'"

Antarctica's contribution to sea-level rise is much smaller than that of Greenland, but according to scientists, this could change in the upcoming century.

Although East Antarctica's massive ice sheet appears to be stable, a recent study found two deep troughs under a major glacier that could draw warm ocean water to the base of the glacier, causing it to melt.