Cli­mate panel: Oceans are in trou­ble and so are we

Re­port warns fail­ure to cut emis­sions will have dire con­se­quences

The Dallas Morning News - - FRONT PAGE - By JU­LIA ROSEN

The planet is in hot wa­ter — lit­er­ally — and that will have dire con­se­quences for hu­man­ity, warns a new United Na­tions re­port on the state of the world’s oceans and ice.

Over the next cen­tury, cli­mate change will make the oceans warmer and more acidic. Melt­ing ice sheets will drive up sea lev­els at an ac­cel­er­at­ing pace. And the pop­u­la­tion of an­i­mals in the sea could drop by as much as 15%, ac­cord­ing to the sober­ing as­sess­ment by the U.N. In­ter­gov­ern­men­tal Panel on Cli­mate Change.

“The oceans and ice are in trou­ble, so we’re all in trou­ble,” said Michael Op­pen­heimer, a cli­mate sci­en­tist at Prince­ton and a lead au­thor of the re­port.

But while some dam­age is in­evitable at this point, the re­port makes clear that so­ci­ety’s ef­forts to re­duce green­house gas emis­sions in the com­ing decades will de­ter­mine how bad things ul­ti­mately get.

It’s “the dif­fer­ence be­tween an un­man­age­able prob­lem and one that hu­mans can deal with,” Op­pen­heimer said.

The anal­y­sis, re­leased Wed­nes­day at a meet­ing of sci­en­tists and pol­i­cy­mak­ers in Monaco, fol­lows close on the heels of the U.N. Cli­mate Ac­tion Sum­mit in New York, which failed to elicit am­bi­tious com­mit­ments from the world’s big­gest pol­luters. Yet the re­port un­der­scores just how costly de­lay­ing ac­tion will be.

Thus far, the world’s oceans have been the quiet hero of the warm­ing world. They have ab­sorbed about a quar­ter of the car­bon diox­ide hu­mans have pumped into the at­mos­phere since the dawn of the in­dus­trial rev­o­lu­tion, and 90% of the re­sult­ing heat.

“But it can’t keep up,” said Ko Bar­rett, deputy ad­min­is­tra­tor for re­search at the Na­tional Oceanic and At­mo­spheric Ad­min­is­tra­tion and a vice chair of the IPCC.

The re­port il­lus­trates how cli­mate change has al­ready started to al­ter the chem­istry and cir­cu­la­tion of the oceans, and how that ex­acts a heavy toll on ma­rine ecosys­tems. Coastal com­mu­ni­ties, which will be home to a bil­lion peo­ple by 2050, are also feel­ing the im­pacts, start­ing with ris­ing seas.

Over the last cen­tury, sea level rise was pri­mar­ily driven by runoff from melt­ing moun­tain glaciers in places like Alaska and the An­des, as well as by the ex­pan­sion of sea­wa­ter as it warmed. Now, the mas­sive ice sheets in Green­land and Antarc­tica have taken over as the largest con­trib­u­tors, and they are in­creas­ing sea lev­els faster than ever.

Since 2006, sea lev­els have risen at a rate of 0.14 of an inch per year — more than dou­ble the rate over the pre­vi­ous cen­tury.

The big ques­tion will hap­pen next?

Based on new re­search since the last IPCC as­sess­ment came out in 2014, the au­thors in­creased their es­ti­mates of pro­jected fu­ture sea lev­els.

Com­pared with the turn of the 21st cen­tury, sea lev­els will in­crease about 1.5 feet by 2100 and will rise a to­tal of 3 feet by the year 2300 — if so­ci­ety rapidly re­duces green­house gases.

That will present plenty of chal­lenges, “but things will evolve slowly, giv­ing hu­mans plenty of time to plan,” Op­pen­heimer said.

On the other hand, if coun­tries fail to curb emis­sions in the next few decades, the world will see about 3 feet of sea level is: What rise by the end of the cen­tury — and much more af­ter that.

In the worst­case sce­nario, where parts of the Antarc­tic ice sheet start to col­lapse, we could be in for as much as 17 feet of sea level rise by 2300. That would prob­a­bly out­pace so­ci­ety’s abil­ity to adapt, Op­pen­heimer said.

No one knows ex­actly where the tip­ping point lies, but sci­en­tists have al­ready seen trou­bling signs of rapid ice loss in places like Antarc­tica’s Th­waites Glacier, which alone con­tains enough wa­ter to raise sea lev­els by 2 feet.

“That is very wor­ry­ing,” said Regine Hock, a glaciol­o­gist at the Univer­sity of Alaska Fair­banks and an au­thor of the re­port. “The in­di­ca­tions are there that in­sta­bil­ity might be on its way.”

Re­gard­less of how much sea lev­els rise over the long term, they will cause prob­lems for coastal com­mu­ni­ties in the short term be­cause of in­creas­ingly dev­as­tat­ing storm surges and high tides.

By 2050, flood events that used to oc­cur only once a cen­tury will hap­pen at least once ev­ery year in many places in the world, even un­der a best­case sce­nario, ac­cord­ing to the re­port.

On top of that, hur­ri­canes will in­ten­sify, and ex­treme El Niño and La Niña events are fore­cast to hap­pen twice as of­ten by the end of the cen­tury. That’s true no mat­ter how quickly coun­tries re­duce green­house gas emis­sions.

Many of these episodes will be un­like any­thing in liv­ing mem­ory, and will re­quire com­mu­ni­ties to plan for un­prece­dented im­pacts. “If we do busi­ness as usual, we won’t be pre­pared for them,” said So­min Cheong, a hu­man ge­og­ra­pher at the Univer­sity of Kansas and an au­thor of the re­port.

The as­sess­ment also looked at how cli­mate change is af­fect­ing fish pop­u­la­tions and the com­mu­ni­ties that de­pend on them.

Warm­ing wa­ters have put many ma­rine an­i­mals on the move. One anal­y­sis found that some fish species along the West Coast could mi­grate as much as 600 miles north un­der a high­emis­sions sce­nario. Crea­tures that can’t re­lo­cate, like corals, could sim­ply be erad­i­cated.

Some an­i­mals will thrive in their new homes and oth­ers will hit dead ends, forc­ing fish­ing in­dus­tries to adapt. But on the whole, un­mit­i­gated cli­mate change will de­crease the po­ten­tial catch of global fish­eries by 20%, the re­port con­cluded.

There is no one­size­fits­all ap­proach to mak­ing coastal com­mu­ni­ties more re­silient, Cheong said, but govern­ments could help by im­prov­ing early warn­ing sys­tems for dis­as­ters, en­cour­ag­ing res­i­dents to plan for cli­mate change when they re­build, or, in some cases, con­sid­er­ing re­treat­ing al­to­gether. But there are also rea­sons to be hope­ful. The ocean holds the po­ten­tial to ac­com­plish roughly a quar­ter of the green­house gas re­duc­tions needed to meet the Paris cli­mate tar­gets, ac­cord­ing to a re­port re­leased Mon­day by the High Level Panel for a Sus­tain­able Ocean Econ­omy, a group of sci­en­tists and world lead­ers con­vened by the World Re­sources In­sti­tute.

For in­stance, sea­grass mead­ows, salt marshes and man­grove habi­tats can se­quester huge amounts of what sci­en­tists call “blue car­bon.” Pre­serv­ing and restor­ing them yields other ben­e­fits too, like buffer­ing coast­lines from storms and serv­ing as nurs­eries for eco­nom­i­cally im­por­tant fish.

Even so, there’s no es­cap­ing the grim pic­ture painted by the IPCC re­port. If cli­mate change con­tin­ues un­abated, “the con­se­quences for hu­man­ity are sweep­ing and se­vere,” Bar­rett said.

“What’s at stake is the health of ecosys­tems, wildlife and — im­por­tantly — the world we leave our chil­dren.”

Tom Copeland/the As­so­ci­ated Press

A storm surge from Hur­ri­cane Do­rian cut Cedar Is­land off from main­land North Carolina ear­lier this month. A U.N. cli­mate re­port projects that if the world fails to curb emis­sions in the next few decades, it will see a 3­foot rise in sea lev­els by the end of the cen­tury — and a rise of up to 17 feet by the year 2300.

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