Dan­ger­ous hot zones spreading

The Prince George Citizen - - Environmen­t - Chris MOONEY

The day the yel­low clams turned black is seared in Ramón Agüero’s mem­ory.

It was the sum­mer of 1994. A few days ear­lier, he had col­lected a gen­er­ous haul, 20 buck­ets of the thin-shelled, cold-wa­ter clams, which bur­row a foot deep into the sand along a 20-km stretch of beach near Barra del Chuy, just south of the Brazil­ian bor­der. Agüero had been dig­ging up these clams since child­hood, a liveli­hood passed on for gen­er­a­tions along these shores.

But on this day, Agüero re­turned to find a dis­as­trous sight: the beach cov­ered in dead clams.

“Kilo­me­tre af­ter kilo­me­tre, as far as our eyes could see. All of them dead, rot­ten, opened up,” re­mem­bered Agüero, now 70. “They were all black, and had a fetid odor.” He wept at the sight.

The clam die-off was an alarm­ing marker of a new cli­mate era, an early sign of this coast­line’s trans­for­ma­tion. Sci­en­tists now sus­pect the event was linked to a gi­gan­tic blob of warm wa­ter ex­tend­ing from the Uruguayan coast far into the South At­lantic, a blob that has only got­ten warmer in the years since.

The mys­te­ri­ous blob cov­ers 337,000 square kilo­me­tres of ocean, an area nearly twice as big as this small coun­try. And it has been heat­ing up ex­tremely rapidly – by over 2 C – over the past cen­tury, dou­ble the global av­er­age. At its cen­tre, it’s grown even hot­ter, warm­ing by as much as 3 C, ac­cord­ing to one anal­y­sis.

The en­tire global ocean is warm­ing, but some parts are chang­ing much faster than oth­ers – and the hot spot off Uruguay is one of the fastest. It was first iden­ti­fied by sci­en­tists in 2012, but it is still poorly un­der­stood and has re­ceived vir­tu­ally no public at­ten­tion.

What re­searchers do know is that the hot zone here has driven mass die-offs of clams, dan­ger­ous ocean heat waves and al­gal blooms, and wide-rang­ing shifts in Uruguay’s fish catch.

The South At­lantic blob is part of a global trend: around the planet, enor­mous ocean cur­rents are trav­el­ing to new lo­ca­tions. As these cur­rents re­lo­cate, wa­ters are growing warmer. Sci­en­tists have found sim­i­lar hot spots along the west­ern stretches of four other oceans – the North At­lantic, the North Pa­cific, the South Pa­cific, and the In­dian.

A Washington Post anal­y­sis of mul­ti­ple tem­per­a­ture data sets found nu­mer­ous lo­ca­tions around the globe that have warmed by at least 2 C over the past cen­tury. That’s a num­ber that sci­en­tists and pol­i­cy­mak­ers have iden­ti­fied as a red line if the planet is to avoid cat­a­strophic and ir­re­versible con­se­quences. But in regions large and small, that point has al­ready been reached.

A study of data from Berke­ley Earth shows how the tem­per­a­ture av­er­age of the last five years com­pares with 1880-1899:

• The Post an­a­lyzed four data sets, and found: roughly one-tenth of the globe has al­ready warmed by more than 2 C, when the last five years are com­pared with the mid- to late 1800s. That’s more than five times the size of the United States.

• About 20 per cent of the planet has warmed by 1.5 C, a point at which sci­en­tists say the im­pacts of cli­mate change grow sig­nif­i­cantly more in­tense.

• The fastest-warm­ing zones in­clude the Arctic, much of the Mid­dle East, Europe and north­ern Asia, and key ex­panses of ocean. A large part of Canada is at 2 C or higher.

Some en­tire coun­tries, in­clud­ing Switzer­land and Kaza­khstan, have warmed by 2 C. Aus­tria has said the same about its famed Alps.

The per­cent­age of the globe that has ex­ceeded 2 C varies depend­ing on the time pe­ri­ods con­sid­ered. Over the past five years, eight to 11 per­cent of the globe crossed the thresh­old, The Post found, while over the past 10 years, the fig­ures drop slightly to be­tween five­and nine per cent. Con­sid­er­ing just the past five years in­creases the area by roughly 40 per cent.

These hot spots are the scenes of a crit­i­cal ac­cel­er­a­tion, places where geo­phys­i­cal pro­cesses are am­pli­fy­ing the gen­eral warm­ing trend. They un­veil which parts of the Earth will suf­fer the largest changes.

Ex­treme warm­ing is help­ing to fuel wild­fires in Alaska, shrink glaciers in the Alps and melt per­mafrost across Canada’s North­west Ter­ri­to­ries. It is al­ter­ing marine ecosys­tems and up­end­ing the lives of fish­er­men who de­pend on them, from Africa to South Amer­ica to Asia.

It is mak­ing al­ready hot places in the Mid­dle East un­bear­able for out­door work­ers and al­ter­ing forests, lakes and rivers in the United States. It has thawed the win­ters of New Eng­land and trans­formed the sum­mers of Siberia.

Over the past five years, Earth has passed a sig­nif­i­cant thresh­old. The planet is now more than 1 C warmer than it was in the mid- to late 1800s, be­fore in­dus­tri­al­iza­tion spread across the world.

The Post’s anal­y­sis re­lied upon four sep­a­rate tem­per­a­ture records from the U.S. gov­ern­ment and sci­en­tific re­searchers. Vari­a­tions in the data sets them­selves, and how they were an­a­lyzed, pro­duce some­what dif­fer­ent as­sess­ments of the ex­tent of the planet that has warmed by 2C.

Be­cause the Earth goes through a num­ber of nat­u­ral cy­cles, cli­mate sci­en­tists con­sider long pe­ri­ods, of mul­ti­ple years, to an­a­lyze tem­per­a­ture change. The Post’s anal­y­sis con­sid­ered two “prein­dus­trial” pe­ri­ods – the 50 years from 1850 to 1899 and the 20 years from 1880 to 1899.

It also con­sid­ered two end pe­ri­ods, the past five years and the past 10, which were com­pared with the two prein­dus­trial pe­ri­ods to de­ter­mine the amount of warm­ing that has taken place.

The past five years are by far the hottest – and dis­play the most nu­mer­ous and ex­pan­sive 2C hot spots. And while five years may be a brief pe­riod in cli­matic terms, 2019 is al­ready fol­low­ing the same ul­tra­warm path­way.

Bar­ring some dra­matic event like a ma­jor vol­canic erup­tion – which can cause tem­po­rary global cool­ing by spew­ing ash that blocks the sun – sci­en­tists ex­pect this to con­tinue and steadily worsen.

“We’re not go­ing to re­ally cool down much in the fu­ture, so the last five years are in­dica­tive of the new nor­mal,” said Zeke Haus­fa­ther, a re­searcher with Berke­ley Earth, which pro­duces one of the data sets The Post an­a­lyzed.

While the global data sets do not agree about what is hap­pen­ing to every stretch of the Earth, they show un­mis­tak­able pat­terns.

For in­stance, an in­trigu­ing group of ocean hot spots ap­pears again and again. One cause? The trop­ics are ex­pand­ing.

Strad­dling the equa­tor, the trop­ics are al­ready hot be­cause they re­ceive the most sun­light. As the sun hits the trop­ics, enor­mous columns of air rise sky­ward and then out­ward. But as green­house gases trap more heat, those columns of air are pushed farther to­ward the north and south poles.

Air that rises in the trop­ics falls back down over the mid­dle lat­i­tudes. With a warm­ing planet, though, the air is fall­ing in dif­fer­ent places.

One re­gion where that air sinks is the South At­lantic Ocean, where the trop­i­cal ex­pan­sion has led to a south­ward shift in the lo­ca­tion of a gi­gan­tic coun­ter­clock­wise cir­cu­la­tion of winds. These winds, in turn, drive key ocean cur­rents, in­clud­ing a warm, salty, 100-kmwide stream called the Brazil Cur­rent, which is be­ing pushed even farther south.

Near Uruguay, the Brazil Cur­rent col­lides with the cold and nu­tri­ent-rich Malv­inas Cur­rent that flows north from wa­ters off Ar­gentina. Where the two cur­rents meet – what is known as the “con­flu­ence” – fea­tures sud­den tem­per­a­ture con­trasts and fos­ters rich fish­eries.

But that zone, too, is on the move. Re­search suggests it is shift­ing south­ward at a rate of more than 70 km per decade.

When tem­per­a­tures rise 1.5 to 2 C for the globe, ac­cord­ing to a re­cent re­port by the United Nations In­ter­gov­ern­men­tal Panel on Cli­mate Change, one of the most se­verely af­fected ocean an­i­mals will be bi­valve species – clams, oys­ters, mus­sels and their rel­a­tives. Above 1.8 C or so, they face “very high risks” of pop­u­la­tion de­cline if not ex­tinc­tion, the re­port said.

Cli­mate change can make for win­ners and losers, es­pe­cially when it comes to fish­eries. Along the U.S. coast, fast-warm­ing wa­ters drove lob­sters away from south­ern New Eng­land and into the Gulf of Maine, lead­ing to crash­ing fish­eries in one spot and a boom in another. That could be hap­pen­ing here, too.

Still, the over­all con­se­quences of these oceanic changes are likely to be neg­a­tive, Franco said. Fish­eries in Uruguay and Brazil are pro­jected to de­cline by more than a quar­ter by the end of the cen­tury.

That could mean ma­jor harm to any num­ber of small-scale fish­eries, far be­yond the com­mu­nity that gath­ers the yel­low clam. Ac­cord­ing to the United Nations’ Food and Agri­cul­ture Or­ga­ni­za­tion, work­ers in these smaller, of­ten lo­cal and sub­sis­tence-driven fish­eries ac­count for 90 per cent of all fish­ery work­ers around the globe, largely in de­vel­op­ing coun­tries. In many cases, they are earn­ing the equiv­a­lent of less than $1 per day.

Sci­en­tists say they are strug­gling to keep up with the im­pacts of a warm­ing world, whether mea­sur­ing changes in the Arctic or dis­ap­pear­ing kelp forests in the south­ern Pa­cific.

“We’re re­ally play­ing catch-up,” said marine sci­en­tist Boris Worm of Dal­housie Univer­sity in Canada.

“Ev­ery­thing we base our civ­i­liza­tion on is based on the ac­cu­mu­lated ex­pe­ri­ence from the last 7,000 years, about how the world works, and how we can sur­vive in this world that had an ex­cep­tion­ally sta­ble cli­mate.

“And we’re shift­ing away from that equi­lib­rium at break­neck speed now. We’re liv­ing in a noana­log world that none of us has any ex­pe­ri­ence with.”

WASHINGTON POST PHOTO/GRAPH­ICS

Top, the sun rises be­hind an empty yel­low clam shell sit­ting on the beach in Barra Del Chuy, Uruguay. Above, this map, us­ing data from Berke­ley Earth, shows how the tem­per­a­ture av­er­age of the last five years com­pares with 1880-1899. Be­low, the rise in global av­er­age tem­per­a­tures.

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