300 mil­lion face an­nual coast­line flood­ing by 2050

The Korea Times - - WORLD -

PARIS (AFP) — Coastal ar­eas cur­rently home to 300 mil­lion peo­ple will be vul­ner­a­ble by 2050 to flood­ing made worse by cli­mate change, no mat­ter how ag­gres­sively hu­man­ity curbs car­bon emis­sions, sci­en­tists said Tues­day.

By mid-cen­tury and be­yond, how­ever, choices made to­day will de­ter­mine whether Earth’s coast­lines re­main rec­og­niz­able to fu­ture gen­er­a­tions, they re­ported in the jour­nal Na­ture Com­mu­ni­ca­tions. De­struc­tive storm surges fu­eled by in­creas­ingly pow­er­ful cy­clones and ris­ing seas will hit Asia hard­est, ac­cord­ing to the study.

More than two-thirds of the pop­u­la­tions at risk are in China, Bangladesh, In­dia, Viet­nam, In­done­sia and Thai­land.

Us­ing a form of ar­ti­fi­cial in­tel­li­gence known as neu­ral net­works, the new re­search cor­rects ground el­e­va­tion data that has up to now vastly un­der­es­ti­mated the ex­tent to which coastal zones are sub­ject to flood­ing dur­ing high tide or ma­jor storms.

“Sea-level pro­jec­tions have not changed,” co-au­thor Ben Strauss, chief sci­en­tist and CEO of Cli­mate Cen­tral, a US-based non-profit re­search group, told AFP.

“But when we use our new el­e­va­tion data, we find far more peo­ple liv­ing in vul­ner­a­ble ar­eas that we pre­vi­ously un­der­stood.”

With the global pop­u­la­tion set to in­crease two bil­lion by 2050 and an­other bil­lion by 2100 — mostly in coastal megac­i­ties — even greater num­bers of peo­ple will be forced to adapt or move out of harm’s way. Al­ready to­day, there are more than 100 mil­lion peo­ple liv­ing be­low high tide lev­els, the study found.

Some are pro­tected by dikes and lev­ees, most are not.

Ris­ing tides, sink­ing cities

“Cli­mate change has the po­ten­tial to re­shape cities, economies, coast­lines and en­tire global re­gions within our life­time,” said lead au­thor and Cli­mate Cen­tral sci­en­tist Scott Kulp.

“As the tide­line rises higher than the ground peo­ple call home, na­tions will in­creas­ingly con­front ques­tions about whether, how much and how long coastal de­fenses can pro­tect them.”

Sev­eral fac­tors con­spire to threaten pop­u­la­tions liv­ing within a few me­ters of sea level.

One is the ex­pan­sion of wa­ter as it warms and, more re­cently, ice sheets atop Green­land and Antarc­tica that have shed more than 430 bil­lion tonnes per year over the last decade.

Since 2006, the wa­ter­line has gone up nearly four mil­lime­ters a year, a pace that could in­crease 100-fold go­ing into the 22nd cen­tury if car­bon emis­sions con­tinue un­abated, the U.N. In­ter­gov­ern­men­tal Panel for Cli­mate Change (IPCC) warned in a ma­jor re­port last month.

If global warming is capped be­low two de­grees Cel­sius — the cor­ner­stone goal of the Paris cli­mate treaty — sea level is pro­jected to rise about half-a-me­ter by 2100.

At cur­rent rates of car­bon pol­lu­tion how­ever, the in­crease would be nearly twice as much.

A sec­ond in­gre­di­ent is trop­i­cal storms — ty­phoons, cy­clones or hur­ri­canes — am­pli­fied by a warming at­mos­phere. “It doesn’t take a big rise in sea level to lead to cat­a­strophic prob­lems,” said Bruce Glavovic, a pro­fes­sor at Massey Univer­sity in New Zealand who was not in­volved in the study.

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