The Antarctic ozone hole has finally started to ‘heal,’ scientists report

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Source: Washington Post

The Antarctic ozone hole has finally started to ‘heal,’ scientists report

By Chris Mooney June 30 at 2:01 PM

In a major new paper in the influential journal Science, a team of researchers report strikingly good news about a thirty year old environmental problem. The Antarctic ozone “hole” — which, when it was first identified in the mid-1980s, focused public attention like few other pieces of environmental news — has begun, in their words, to finally “heal.”

“If you use the medical analogy, first the patient was getting worse and worse, and then the patient is stabilized, and now, the really encouraging thing, is that the patient is really starting to get better,” said MIT atmospheric scientist Susan Solomon, lead author of the study, and former co-chair of the United Nations’ Intergovernmental Panel on Climate Change.

And moreover, that patient — the Earth’s vital ozone layer — is getting better directly because of our choices and policies.

The initial, Nobel Prize winning discovery that ozone depleting chemicals called chlorofluorocarbons (CFCs) carried in refrigerants, spray cans, foams and other substances could damage the stratospheric layer that protects us from ultraviolet solar radiation (and thus, skin cancer) came in 1974. But it wasn’t until the sudden discovery of a vast seasonal ozone “hole” over Antarctica in 1985 that the world was shocked into action.

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Read more: https://www.washingtonpost.com/news/energy-environment/wp/2016/06/30/the-antarctic-ozone-hole-has-finally-started-to-heal-scientists-report/


[font size=1]This false-color image shows ozone concentrations above Antarctica on Oct. 2, 2015. (Credits: NASA/Goddard Space Flight Center)[/font]

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1. Animation

http://news.mit.edu/2016/signs-healing-antarctic-ozone-layer-0630

[font face=Serif][font size=5]Scientists observe first signs of healing in the Antarctic ozone layer[/font]
[font size=4]September ozone hole has shrunk by 4 million square kilometers since 2000.[/font]

Jennifer Chu | MIT News Office
June 30, 2016

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The team did observe an important outlier in the trend: In 2015, the ozone hole reached a record size, despite the fact that atmospheric chlorine continued to drop. In response, scientists had questioned whether any healing could be determined. Going through the data, however, Solomon and her colleagues realized that the 2015 spike in ozone depletion was due primarily to the eruption of the Chilean volcano Calbuco. Volcanoes don’t inject significant chlorine into the stratosphere but they do increase small particles, which increase the amount of polar stratospheric clouds with which the human-made chlorine reacts.

“Why I like this paper so much is, nature threw us a curveball in 2015,” says Ross Salawitch, professor of chemistry and biochemistry at the University of Maryland. “People thought we set a record for the depth of the ozone hole in October 2015. The Solomon paper explains it was due to a specific volcanic eruption. So without this paper, if all we had was the data, we would be scratching our heads — what was going on in 2015?”

As chlorine levels continue to dissipate from the atmosphere, Solomon sees no reason why, barring future volcanic eruptions, the ozone hole shouldn’t shrink and eventually close permanently by midcentury.

“What’s exciting for me personally is, this brings so much of my own work over 30 years full circle,” says Solomon, whose research into chlorine and ozone spurred the Montreal Protocol. “Science was helpful in showing the path, diplomats and countries and industry were incredibly able in charting a pathway out of these molecules, and now we’ve actually seen the planet starting to get better. It’s a wonderful thing.”

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2. We'll see

Hole size has increased over the past 4 years (2012-15) to the fourth largest ever, and concentration of ozone has gone down quite a bit over those same 4 years.

http://ozonewatch.gsfc.nasa.gov/statistics/annual_data.html