NASA sees un­avoid­able sea level rise ahead


Sea lev­els are ris­ing around the world, and the latest satel­lite data sug­gests that 1 me­ter (3 feet) or more is un­avoid­able in the next 100-200 years, NASA sci­en­tists said Wed­nes­day.

Ice sheets in Green­land and Antarc­tica are melt­ing faster than ever, and oceans are warm­ing and ex­pand­ing much more rapidly than they have in years past.

Ris­ing seas will have “pro­found im­pacts” around the world, said Michael Freilich, di­rec­tor of NASA’s Earth Science Di­vi­sion.

“More than 150 mil­lion peo­ple, most of them in Asia, live within one me­ter of present sea level,” he said.

Low-ly­ing U.S. states such as Florida are at risk of dis­ap­pear­ing, as are some of the world’s ma­jor cities such as Sin­ga­pore and Tokyo.

“It may en­tirely elim­i­nate some Pa­cific is­land na­tions,” he said.

There is no doubt that global coast­lines will look very dif­fer­ent in years to come, U.S. space agency ex­perts told re­porters on a con­fer­ence call to dis­cuss the latest data on sea level rise.

“Right now we have com­mit­ted to prob­a­bly more than 3 feet (1 me­ter) of sea level rise, just based on the warm­ing we have had so far,” said Steve Nerem of the Univer­sity of Colorado, Boul­der and leader of NASA’s sea level rise team.

“It will very likely get worse in the fu­ture,” he told re­porters.

“The big­gest un­cer­tainty is pre­dict­ing how quickly the po­lar ice sheets will melt.”

Melt­ing Faster

The last ma­jor pre­dic­tions were made in 2013 by the United Na­tions In­ter­gov­ern­men­tal Panel on Cli­mate Change (IPCC).

Based on a con­sen­sus of in­ter­na­tional re­searchers, the IPCC said global sea lev­els would likely rise from 0.3 to 1 me­ters by the end of the cen­tury.

Nerem said the latest satel­lite data sug­gests the higher end of that range is more likely.

NASA’s pre­dic­tions are based on a se­ries of al­time­ters that mea­sure ocean height from space. NASA and French space agency CNES be­gan launch­ing satel­lites to mea­sure sea level in 1992.

“The in­stru­ments are so sen­si­tive that if they were mounted on a com­mer­cial jet­liner fly­ing at 1,200 me­ters (40,000 feet) they could de­tect the bump caused by a dime ly­ing flat on the ground,” Freilich said.

The world’s oceans have risen an av­er­age of al­most 7.6 cen­time­ters (3 inches) since 1992, with some lo­ca­tions ris­ing more than 23 cen­time­ters ( 9 inches) due to nat­u­ral vari­a­tion, ac­cord­ing to these in­stru­ments, known as Topex/Po­sei­don, and its suc­ces­sors, Jason-1 and Jason-2, NASA said.

Much of the ex­tra wa­ter is com­ing from melt­ing ice and glaciers. Sci­en­tists are par­tic­u­larly con­cerned about the Green­land ice sheet, which shed an av­er­age of 303 gi­ga­tons of ice a year over the past decade.

Also, the Antarc­tic ice sheet has lost an av­er­age of 118 gi­ga­tons a year.

“One of the things we have learned is that the ice sheets are melt­ing faster than we had pre­vi­ously sus­pected,” said Josh Wil­lis, oceanog­ra­pher at NASA’s Jet Propul­sion Lab­o­ra­tory in Pasadena, Cal­i­for­nia.

“Some­time in the next 20 years we will prob­a­bly see faster than av­er­age sea level rise, so we have to be pre­pared.”

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