Ozone depletion, health and the environment, and interactions with climate change

Gems from the Just-Published Assessment

It’s almost like a catch cry for UV & You. Everything you ever wanted to know - and probably more (!) - about ozone depletion and its effects on human health and the environment, and their interactions with climate change. This one-stop shop for all those things has just been published.

Assessments like this are produced every four years by the United Nation Environment Program (UNEP) and made available to the public here. In this time of 4-letter acronyms, the assessment team is called the “Environmental Effects Assessment Panel” (EEAP). I’ve been involved with them since the early 1990s. Over those years, my main contribution has been mainly with the first chapter, which links ozone science to UV effects.

This year’s version was led by my old friend, Germar Bernhard. I’m biased, but for me the most interesting thing there was the update below from our 2019 paper that was published in Nature Scientific Reports. Somebody else agrees too because it was selected as the graphical abstract.

Relative changes in the UVI between 1996 and 2020 for summer (a) and spring (b), from observations at nine ground stations (black symbols) and calculated from results of two chemistry-climate models (blue lines). Both climate models assume the “World Avoided” scenario where emissions of ozone-depleting substances are not controlled by the Montreal Protocol. Blue shading indicates the range of these model projections. Ground stations include South Pole (90° S), Arrival Heights (78° S), Palmer Station (65° S), Lauder (45° S), Alice Springs (24° S), Mauna Loa (20° N), Boulder (40° N), Thessaloniki (41° N), and Barrow Alaska(71° N). Those with a near-complete data record for 1996–2020 are indicated by solid symbols, while those with fewer than 24 years of data are shown with open symbols.

The figure clearly demonstrates that the Montreal Protocol is still working. Over the period for 1996 to 2020, the UV has remained stable or decreased at all sites except one. Without the Montreal Protocol, those UV values at high southern latitudes would have increased by 50 percent or more in summer, and by 100 percent or more in spring.

Thessaloniki (Greece) is the only location where there have been significant increases in UV. But that has nothing to do with ozone. The increases there are due to reductions in the effects of clouds and aerosols. Elsewhere in the assessment, it is reported that increases in UV have been seen in Mexico City since due to improvements in air quality. Summer peaks there have increased by about 30 percent since the turn of the century, with largest changes in the period since 2015.

There’s a lot of other great stuff there, some of which I’ve mentioned in earlier posts. Take a look. It’s mostly good news.