20 Apr 2017 The New York Times

Study Shows Plastic Debris Finding Path To the Arctic

The world’s oceans are lit­tered with tril­lions of pieces of plas­tic — bot­tles, bags, toys, fish­ing nets and more, most­ly in tiny par­ti­cles — and now this seaborne junk is mak­ing its way in­to the Arctic.

In a study pub­lished Wednesday in Science Advances, a group of re­searchers from the University of Cádiz in Spain and sev­er­al oth­er in­sti­tu­tions show that a ma­jor ocean cur­rent is car­ry­ing bits of plas­tic, main­ly from the North Atlantic, to the Greenland and Barents seas, and leav­ing them there — in sur­face wa­ters, in sea ice and pos­si­bly on the ocean floor.

Because cli­mate change is al­ready shrink­ing the Arctic sea ice cov­er, more hu­man ac­tiv­i­ty in this still-isolated part of the world is in­creas­ing­ly like­ly as nav­i­ga­tion be­comes eas­i­er. As a re­sult, plas­tic pol­lu­tion, which has grown sig­nif­i­cant­ly around the world since 1980, could spread more wide­ly in the Arctic in decades to come, the re­searchers say.

Fragments of fish­ing lines found in Arctic sur­face wa­ters by the re­search team

Andrés Cózar Cabañas, the study’s lead au­thor and a pro­fes­sor of bi­ol­o­gy at the University of Cádiz, said he was sur­prised by the re­sults, and wor­ried about pos­si­ble out­comes.

“We don’t ful­ly un­der­stand the con­se­quences the plas­tic is hav­ing or will have in our oceans,” he said. “What we do know is that this con­se­quences will be felt at greater scale in an ecosys­tem like this” be­cause it is un­like any oth­er on Earth.

Every year, about 8 mil­lion tons of plas­tic gets in­to the ocean, and sci­en­tists es­ti­mate that there may be as much as 110 mil­lion tons of plas­tic trash in the ocean. Though the en­vi­ron­men­tal ef­fects of plas­tic pol­lu­tion are not ful­ly un­der­stood, plas­tic pol­lu­tion has made its way in­to the food chain. Plastic de­bris in the ocean was thought to ac­cu­mu­late in big patch­es, most­ly in sub­trop­i­cal gyres — big cur­rents that con­verge in the mid­dle of the ocean — but sci­en­tists es­ti­mate that on­ly about 1 per­cent of plas­tic pol­lu­tion is in these gyres and oth­er sur­face wa­ters in the open ocean.

Another mod­el of ocean cur­rents by one of the study’s au­thors pre­dict­ed that plas­tic garbage could al­so ac­cu­mu­late in the Arctic Ocean, specif­i­cal­ly in the Barents Sea, lo­cat­ed off the north­ern coasts of Russia and Norway, which this study demon­strates.

The sur­face wa­ter plas­tic in the Arctic Ocean cur­rent­ly ac­counts for on­ly about 3 per­cent of the to­tal, but the au­thors sug­gest the amount will grow and that the seafloor there could be a big sink for plas­tic.

This par­tic­u­lar part of the ocean is im­por­tant in the ther­mo­ha­line cir­cu­la­tion, a deep­wa­ter glob­al cur­rent dic­tat­ed by dif­fer­ences in tem­per­a­ture and salin­i­ty around the world. As that cur­rent brings warm sur­face wa­ter up to the Arctic, it seems to be bring­ing with it plas­tic waste from more dense­ly pop­u­lat­ed coast­lines, dump­ing the now-fragmented pieces of plas­tic in the Arctic, where land­mass­es like Greenland and the po­lar ice cap trap them.

The sci­en­tists sam­pled float­ing plas­tic de­bris from 42 sites in the Arctic Ocean aboard Tara, a re­search ves­sel that com­plet­ed a trip around the North Pole from June to October 2013, with da­ta from two ad­di­tion­al sites from a pre­vi­ous trip. They scooped up plas­tic de­bris and de­ter­mined the con­cen­tra­tion of par­ti­cles by di­vid­ing the dry weight of the plas­tic col­lect­ed, ex­clud­ing mi­crofibers, by the area sur­veyed.

Almost all of the plas­tic, mea­sured by weight, was in frag­ments, most­ly rang­ing from 0.5 mil­lime­ters to 12.6 mil­lime­ters. The rest of the plas­tic ap­peared in the form of fish­ing line, film or pel­lets. This mix of plas­tic types is rough­ly con­sis­tent with the kinds of plas­tic that col­lect in the sub­trop­i­cal gyres, though those parts of the ocean amass­es a high­er con­cen­tra­tion of fish­ing line.

The re­searchers did not find many large pieces of plas­tic, nor did they find much plas­tic film, which breaks down quick­ly, sug­gest­ing that the plas­tic has al­ready been in the ocean for a while by the time it gets to the Arctic.

If the plas­tics were com­ing di­rect­ly from Arctic coast­lines, it would mean that peo­ple in the sparse­ly pop­u­lat­ed Arctic were de­posit­ing many more times the plas­tic in the ocean than peo­ple in oth­er parts of the world, which is un­like­ly. Shipping is al­so rel­a­tive­ly in­fre­quent there and, the au­thors write, there is no rea­son to think that flot­sam or jet­sam in the Arctic would be so much high­er than in oth­er parts of the world.

The les­son from the study, Dr. Cózar Cabañas said, is that the is­sue of plas­tic pol­lu­tion “will re­quire in­ter­na­tion­al agree­ments.”

“This plas­tic is com­ing from us in the North Atlantic,” he said. “And the more we know about what hap­pens in the Arctic, the bet­ter chance we have” of solv­ing the prob­lem.