Ozone Interactions

The ozone layer has no ozone anymore
and you're gonna leave me for the guy next door
I'm Sick of You
~~ Lou Reed

I use the song "Sick of You" from the 1989 New York album to introduce the concept of ozone depletion in my environmental geography classes. The song is a quick catalog of the absurd environmental and political debacles of the Reagan years, but includes the charming couplet and refrain cited above. 

My point? Geography is the study of the real world.  

It was during the 1980s that climate change was just beginning to gain some attention as a problem for the far-off future and that the depletion of stratospheric ozone -- globally but especially around Antarctica -- was emerging as a more urgent concern. The science was debated and for some time actively denied -- as inconvenient science sometimes is. But as people realized that the problem could be addressed without serious inconvenience to them personally, the denial melted away and in 1987 the Montreal Protocol was signed.

For some time in the 90s and aughts, both global warming and ozone depletion were being discussed and debated. Since geography education is rare in the United States, much of that discussion took place in the absence of a basic understanding of the structure of the atmosphere, the reasons for geographic variations in climate, or indeed the basic relationships between the earth and the sun. 

Folks who do not know what the tropopause is nonetheless had strong opinions about problems taking place above and below it. Well-meaning people who want to protect the planet often have no better understanding of climate change, ozone depletion, or the difference between the two than do those who actively deny the science.

Enter this environmental geographer, seeking to clarify things for students who have heard about both problems -- but only vaguely. 

In order to focus on climate change, I begin many of my courses with an exercise that is focused on drawing a distinguishing it from ozone depletion. I start with a simple pre-test that asks students to identify distinctions, and a post-test that highlights those distinctions in some detail. I then spend one session on the details of ozone depletion, not returning to it much for the rest of the course. 

All of this is prelude to some emerging science that is cause both for concern and for confusion. All I have said about distinctions between tropospheric and stratospheric processes remains true, but there is now a serious caveat. 

I learned of the problem from the EuroNews Green newsletter, in a September 2021 article by journalist Rafael Cereceda with the earnest title "The Antarctic ozone hole is among the largest on record, how does it affect me?" The opening line of the article reflects what has been the broad consensus I have been teaching: "What happens in the stratosphere stays in the stratosphere?" The question mark, of course, suggests that the rest of the article is likely to disrupt that consensus. 

(Note: as of this writing, the article includes one grammatical (it's for its) and one arithmetic (square meters for square kilometers) error; I have contacted the publisher about both. The author uses Hadley Cell and other complicated concepts correctly, though, so I consider the errors isolated.)

The article does cite some fairly long-standing work that has been an exception to the general consensus: since the 1990s there ha been some inconclusive work on possible connections between ozone depletion and circulation changes in the mid-southern latitudes.

The article was. published at the time of year we expect news about ozone depletion. During the southern winter, it gets very cold in Antarctica. VERY cold. So cold that the normal rules about atmospheric heating and cooling do not apply, and the lower stratosphere experiences cooling that in turn creates clouds (in the dark) at altitudes they usually cannot be formed. When the first light of spring -- which coincides with Northern Hemisphere autumn -- reactions take place in those clouds that catalyze ozone depletion. 

This September, the news was that the size of the "hole" created by this process had been larger than normal. The article explains the significance in some detail: the 2019 ozone hole had been the smallest on record (because measurements were not made until the problem had been growing for a couple of decades). This had led to an unwarranted level of optimism among many analysts. 

Ozone "hole" upside down and backwards.
Image: Yan Xia

The article is also an occasion to share even more unusual news: in March 2020 a significant ozone "hole" was observed over the Arctic Ocean. The timing is consistent with previous observations: March is the north-pole vernal equinox, just as September is the vernal equinox at the south pole. What makes this story unique is that the north pole does not get nearly as cold as the south pole -- especially in recent years. Cereceda provides a link to a press release that summarizes an article explaining the dynamics of the 2020 northern ozone hole, in terms of a modified polar vortex.

Lagniappe 

The album includes one cetacean offering -- Last Great American Whale -- an allegory in which Professor Reed (as I often call him) disparages the state of environmental consciousness in his decade. For the past decade I have taken a great interest in whales and whaleboats. See my Rowing and Rocket Science;  Whaleboat History; and Finity posts for some of the better examples.