Earth’s ozone hole shriv­els to small­est since 1988

Sun.Star Pampanga - - SCIENCE! -

WASHINGTON

(AP) — The ozone hole over Antarc­tica shrank to its small­est peak since 1988, NASA said Thurs­day.

The huge hole in Earth’s pro­tec­tive ozone layer reached its max­i­mum this year in Septem­ber, and this year NASA said it was 7.6 mil­lion square miles wide (19.6 mil­lion square kilo­me­ters). The hole size shrinks after mid-Septem­ber.

This year’s max­i­mum hole is more than twice as big as the United States, but it’s 1.3 mil­lion square miles less than last year and 3.3 mil­lion square miles smaller than 2015.

Paul New­man, chief Earth sci­en­tist at NASA’s God­dard Space Flight Cen­ter, said stormy con­di­tions in the up­per at­mos­phere warmed the air and kept chem­i­cals chlo­rine and bromine from eat­ing ozone. He said sci­en­tists haven’t quite fig­ured out why some years are stormier — and have smaller ozone holes — than oth­ers.

“It’s re­ally small this year. That’s a good thing,” New­man said.

New­man said this year’s drop is mostly nat­u­ral but is on top of a trend of smaller steady im­prove­ments likely from the ban­ning of ozone-eat­ing chem­i­cals in a 1987 in­ter­na­tional treaty. The ozone hole hit its high­est in 2000 at 11.5 mil­lion square miles (29.86 mil­lion square kilo­me­ters).

Ozone is a col­or­less com­bi­na­tion of three oxy­gen atoms. High in the at­mos­phere, about 7 to 25 miles (11 to 40 kilo­me­ters) above the Earth, ozone shields Earth from ul­tra­vi­o­let rays that cause skin cancer, crop dam­age and other prob­lems.

Sci­en­tists at the United Na­tion a few years ago de­ter­mined that with­out the 1987 treaty by 2030 there would have been an ex­tra 2 mil­lion skin cancer cases. They said over­all the ozone layer is be­gin­ning to re­cover be­cause of the phase­out of chem­i­cals used in re­frig­er­ants and aerosol cans.

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