Published: Sat, January 06, 2018
Science | By Eileen Rhodes

New NASA Data Suggests The Hole In The Ozone Layer Is Shrinking

New NASA Data Suggests The Hole In The Ozone Layer Is Shrinking

The ozone hole spurred countries and companies into action and the Montreal Protocol codified an agreement to slow down use of CFCs which appears to be working, reported.Hints of a recovery have often been followed by years in which ozone levels drop again.

The 20 percent decrease in ozone depletion during the winter months from 2005 to 2016 as determined from MLS ozone measurements was expected. Specifically chlorine levels declined by 0.8 percent each year between 2005 and 2016.

The new study is the first time anyone accurately measured chlorine levels inside the ozone hole, confirming that the Montreal Protocol is indeed doing its job, says NASA.

The chlorofluorocarbons (CFCs) Strahan referred to are ozone-depleting chemicals that were once used in aerosol sprays, blowing agents for foams and packing materials, and refrigerants. As the ozone layer acts as a protective blanket against the most harmful wavelengths of ultraviolet light, the so-called (and then-expanding) hole over Antarctica brought with it visions of skin cancer, sunburn, cataracts, and havoc to plants and animals, for starters. Just two years after the hole was discovered, the world jumped quickly to solve the problem.

New NASA study offers first direct proof that the ozone hole is recovering thanks to the Montreal Protocol treaty and the global ban on CFCs. "This is when we want to measure ozone loss".

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Previously, such research argued that ozone depletion is decreasing based on statistical analyses of changes in the ozone hole's size. Using data since 2005 from the Microwave Limb Sounder on the Aura satellite, scientists gathered information on the amount of hydrochloric acid in the stratosphere, where the ozone layer is located. Chlorine, in particular, is very harmful since these atoms are extremely reactive with ozone.

"During this period, Antarctic temperatures are always very low, so the rate of ozone destruction depends mostly on how much chlorine there is", Strahan said. "This gives us confidence that the decrease in ozone depletion through mid-September shown by [Microwave Limb Sounder] data is due to the declining levels of chlorine coming from CFCs".

The MLS measures microwave emissions and trace gases over the Antarctic.

Scientists at NASA said they had located the largest ozone hole ever recorded, in a report released October 3, 2000.

Last year, satellite images showed the hole had begun to close and could be completely healed by 2060. "But we're not yet seeing a clear decrease in the size of the ozone hole because that's controlled mainly by temperature after mid-September, which varies a lot from year to year".

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