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SCIENCE ALERT MAGAZINE ARTICLE 26 MARCH 2020: Earth’s Ozone Layer Is Healing and Bringing Some Good News on Global Wind Movement, CARLY CASSELLA, 26 MARCH 2020

The ozone layer above Antarctica has recovered so much, it’s actually stopped many worrying changes in the Southern Hemisphere’s atmosphere. If you’re looking for someone to thank, try the world at large. A new study suggests the Montreal Protocol – the 1987 agreement to stop producing ozone depleting substances (ODSs) – could be responsible for pausing, or even reversing, some troubling changes in air currents around the Southern Hemisphere. Swirling towards our planet’s poles at a high altitude are fast air currents known as jet streams. Before the turn of the century, ozone depletion had been driving the southern jet stream further south than usual. This ended up changing rainfall patterns, and potentially ocean currents as well. Then, a decade or so after the protocol was signed, that migration suddenly stopped.

Was it a coincidence? Using a range of models and computer simulations, researchers have now shown this pause in movement was not driven by natural shifts in winds alone. Instead, only changes in the ozone could explain why the creep of the jet stream had suddenly stopped. In other words, the impact of the Montreal Protocol appears to have paused, or even slightly reversed, the southern migration of the jet stream. And for once, that’s actually good news.

In Australia, for instance, changes to the jet stream have increased the risk of drought by pushing rain away from coastal areas. If the trend does reverse, those rains might return.
“The ‘weather bands’ that bring our cold fronts have been narrowing towards the south pole, and that’s why southern Australia has experienced decreasing rainfall over the last thirty years or so,” says Ian Rae, organic chemist from the University of Melbourne who was not involved in the study. “If the ozone layer is recovering, and the circulation is moving north, that’s good news on two fronts (pun not intended).”

Still, we may not be celebrating for long. While improvements in cutting back our reliance on ODSs have certainly allowed the ozone to recover somewhat, carbon dioxide levels continue to creep upwards and place all that progress at risk.
Last year, the Antarctic ozone hole hit its smallest annual peak on record since 1982, but the problem isn’t solved, and this record may have something to do with unusually mild temperatures in that layer of the atmosphere. What’s more, in recent years, there’s been a surge in ozone-depleting chemicals, coming from industrial regions in China.

“We term this a ‘pause’ because the poleward circulation trends might resume, stay flat, or reverse,” says atmospheric chemist Antara Banerjee from the University of Colorado Boulder. “It’s the tug of war between the opposing effects of ozone recovery and rising greenhouse gases that will determine future trends.” The Montreal Protocol is proof that if we take global and immediate action we can help pause or even reverse some of the damage we’ve started. Yet even now, the steady rise in greenhouse gas emissions is a reminder that one such action is simply not enough.

The cited research paper is “A pause in Southern Hemisphere circulation trends due to the Montreal Protocol, Antara Banerjee, John C. Fyfe, Lorenzo M. Polvani, Darryn Waugh & Kai-Lan Chang, Nature volume 579, pages544–548(2020): ABSTRACT:  Observations show robust near-surface trends in Southern Hemisphere tropospheric circulation towards the end of the twentieth century, including a poleward shift in the mid-latitude jet, a positive trend in the Southern Annular Mode and an expansion of the Hadley cell. It has been established that these trends were driven by ozone depletion in the Antarctic stratosphere due to emissions of ozone-depleting substances. Here we show that these widely reported circulation trends paused, or slightly reversed, around the year 2000. Using a pattern-based detection and attribution analysis of atmospheric zonal wind, we show that the pause in circulation trends is forced by human activities, and has not occurred owing only to internal or natural variability of the climate system. Furthermore, we demonstrate that stratospheric ozone recovery, resulting from the Montreal Protocol, is the key driver of the pause. The pre-2000 circulation trends adversely affected precipitation, ocean circulation and salinity, we expect that a pause in these trends will have a beneficial impact on climate and that therefore the Montreal Protocol may have other beneficial climate impacts.

CRITICAL COMMENTARY

1. On the eve of COP26 in Glasgow and in the context of a failure to achieve a global agreement to tackle climate change by cutting fossil fuel emissions, this paper presents the claimed success of the Montreal Protocol to solve a global environmental crisis with global agreement and coordination as an encouraging model for a similar outcome in global climate action. It is noted that the paper is from Columbia University [LINK] .
2. A similar theme is found in a related post [LINK] where another paper from Columbia University  presents the presumed success of the Montreal Protocol in terms of global cooperation against a global environmental problem. It is implicitly proposed as an encouraging sign that the same kind of success should be possible in a parallel Climate Protocol, possibly at the COP26. As a way of establishing a relationship between climate change and ozone depletion, the paper finds ways to relate climate issues to the assumed success of the Montreal Protocol in solving the ozone depletion crisis. Both of these papers are from Columbia University  [LINK]  .
3. In the paper presented here on the success of the Montreal Protocol in halting ozone depletion, the authors propose an amazing connection between the ozone depletion at the South Pole (as in the so called ozone hole) and climate change in the South Polar region. It claims that the success of the Montreal Protocol’s action against ozone depletion has caused the ozone hole to heal and that in turn has benefited the climate in terms of halting harmful changes in the jet stream caused by fossil fuel emissions. In this way the environmental harm of ozone depleting substances and fossil fuel emissions are combined into an overarching environmental issue. On this basis, the paper glorifies the Montreal Protocol as a model for global agreements to tackle global environmental issues. It appears that the intent of the paper is to boost morale and encouragement for a global climate agreement at COP26 in the face of a disheartening failure at the previous 25 COP meetings.
4. In terms of the ozone depletion and ozone depleting substances it should be noted that in the case against CFC as an ozone depleting substance (ODS) the primary issue is its long life in the atmosphere once released, estimated to be 150 years. Therefore it is unlikely that the ban on ODS release into the atmosphere will have a measurable effect on either ozone concentration or on ODS concentration at a decadal time scale as assumed in this paper.
5. It should also be mentioned that although the ozone hole has been used as a high profile issue in the fight against ODS and although the only evidence of ozone depletion in support of the Rowland Molina theory of ozone depletion by ODS was ozone depletion in the South Pole by Farman et al, the real ozone issue is not what happens at the South Pole or in any other specific location. The real issue is mean global ozone levels. These and other issues are presented in a related post where it is shown that the Farman etal paper, the only empirical evidence of the Rowland Molina theory of ozone depletion, is flawed and therefore not credible [LINK] .
6. However, the primary flaw of the paper presented here is that it is not possible to interpret the effect of Montreal Protocol at decadal time scales because these changes are slow and they should be studied at centennial time scales. The other important issue is that the the impact of ozone depletion and ozone depleting substances should be studied on a global basis and they can’t be interpreted in a localized basis as discussed in the related post on Farman etal [LINK].
7. It should also be considered that the ozone hole does not serve as evidence of global ozone depletion because ozone depletion has a global distribution interpretation.  In related posts it is shown that there is no empirical evidence of global ozone depletion or of its recovery by way of the Montreal Protocol [LINK] [LINK] [LINK] [LINK] [LINK] [LINK]  . The only empirical evidence of the Rowland Molina theory of ozone depletion is Farman etal 1985 and as shown here [LINK]  that study is flawed.
8. As a footnote, the evidence of a causation relationship between ozone recovery and jet stream recovery (other than that they could not find any other explanation for it) is that they both began in the year 2000. This kind of coincidence as causation is common in climate science, as in “the industrial economy began burning fossil fuels and at the same time the atmospheric CO2 levels began to rise. This kind of relationship does not prove causation as Tyler Vigen has so expertly demonstrated in his spurious correlation site [LINK] and as described in a related post [LINK]

CONCLUSION: THE ATTEMPT BY THE CITED PAPER TO RELATE JET STREAM CHANGES TO THE SUCCESS OF THE MONTREAL PROTOCOL IN THE REDUCTION OF OZONE DEPLETING SUBSTANCES AND THE HALTING OF OZONE DEPLETION IN THE STRATOSPHERE AT DECADAL TIME SCALES IS NOT CREDIBLE. THE PAPER’S INTENT IS THEREFORE INTERPRETED AS ACTIVISM TO PROMOTE THE MONTREAL PROTOCOL AS A MODEL FOR A CLIMATE ACTION POSSIBLY AS PREPARATION FOR THE UPCOMING COP26 CLIMATE MEETING IN GLASGOW.