Good news for ozone hole

St. Thomas Times-Journal - - SPORTS - SETH BOREN­STEIN

WASHINGTON — Earth’s pro­tec­tive ozone layer is fi­nally heal­ing from dam­age caused by aerosol sprays and coolants, a new UN re­port said.

The ozone layer had been thin­ning since the late 1970s. Sci­en­tists raised the alarm and ozonede­plet­ing chem­i­cals were phased out world­wide.

As a re­sult, the up­per ozone layer above the North­ern Hemi­sphere should be com­pletely re­paired in the 2030s and the gap­ing Antarc­tic ozone hole should dis­ap­pear in the 2060s, ac­cord­ing to a sci­en­tific as­sess­ment re­leased Mon­day at a con­fer­ence in Quito, Ecuador. The South­ern Hemi­sphere lags a bit and its ozone layer should be healed by mid-cen­tury.

“It’s re­ally good news,” said re­port co-chair­man Paul New­man, chief Earth sci­en­tist at NASA’s Goddard Space Flight Cen­ter.

“If ozone-de­plet­ing sub­stances had con­tin­ued to in­crease, we would have seen huge ef­fects. We stopped that.”

High in the at­mos­phere, ozone shields Earth from ul­tra­vi­o­let rays that cause skin can­cer, crop dam­age and other prob­lems. Use of man-made chem­i­cals called chlo­roflu­o­ro­car­bons (CFCs), which re­lease chlo­rine and bromine, be­gan eat­ing away at the ozone.

In 1987, coun­tries around the world agreed in the Mon­treal Pro­to­col to phase out CFCs and busi­nesses came up with re­place­ments for spray cans and other uses.

At its worst in the late 1990s, about 10 per cent of the up­per ozone layer was de­pleted, New­man said. Since 2000, it has in­creased by about one to three per cent per decade, the re­port said.

This year, the ozone hole over the South Pole peaked at nearly 24.8 mil­lion sq. km. That’s about 16 per cent smaller than the big­gest hole recorded — 29.6 mil­lion sq. km in 2006.

The hole reaches its peak in Septem­ber and Oc­to­ber and dis­ap­pears by late De­cem­ber un­til the next South­ern Hemi­sphere spring, New­man said.

The ozone layer starts at about 10 km above Earth and stretches for nearly 40 km; ozone is a colour­less com­bi­na­tion of three oxy­gen atoms.

If noth­ing had been done to stop the thin­ning, the world would have de­stroyed two-thirds of its ozone layer by 2065, New­man said.

But it’s not a com­plete suc­cess yet, said Univer­sity of Colorado’s Brian Toon, who wasn’t part of the re­port.

“We are only at a point where re­cov­ery may have started,” Toon said, point­ing to some ozone mea­sure­ments that haven’t in­creased yet.

An­other prob­lem is that new tech­nol­ogy has found an in­crease in emis­sions of a banned CFC out of East Asia, the re­port noted.

On its own, the ozone hole has slightly shielded Antarc­tica from the much larger ef­fects of global warm­ing — it has heated up but not as much as it likely would with­out ozone de­ple­tion, said Ross Salaw­itch, a Univer­sity of Mary­land at­mo­spheric sci­en­tist who co-au­thored the re­port.

So a healed ozone layer will worsen man-made cli­mate change there a bit, New­man said.

Sci­en­tists don’t know how much a healed ozone hole will fur­ther warm Antarc­tica, but they do know the im­me­di­ate ef­fects of ozone de­ple­tion on the world and hu­man health, so “it would be in­cred­i­bly ir­re­spon­si­ble not to do this,” Salaw­itch said.

NASA VIA THE AS­SO­CI­ATED PRESS

This com­bi­na­tion of images shows ar­eas of low ozone above Antarc­tica in Septem­ber 2000, left, and Septem­ber 2018. The pur­ple and blue colours are where there is the least ozone, and the yel­lows and reds are where there is more ozone. A UN re­port says Earth’s pro­tec­tive ozone layer is fi­nally heal­ing.

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