Ref:  UNEP/EO/Ozone Staff                                                                                                                    30 September 2020

Dear Parties to the Vienna Convention and the Montreal Protocol,

With reference to Ms. Tina Birmpili’s departure from the position of Executive Secretary of Ozone Secretariat at the end of this month, I wish to take this opportunity to inform you that Ms. Meg Seki, currently Deputy Executive Secretary, has been designated as Acting Executive Secretary, effective 1 October.

As you may be aware, Ms. Seki, a national of Japan, has had a longstanding involvement on ozone layer issues, having joined as one of the first staff members in the Secretariat when it was formally established in 1989. She has had notable experience, working on the establishment of ozone country programmes, the regional ozone networks, global environmental assessments, climate change issues, transboundary air pollution, among others. She rejoined the Ozone Secretariat in 2003 and is currently the Deputy Executive Secretary. I remain confident that Ms. Seki in her acting capacity will very ably steer the Secretariat, as was done by Ms. Birmpili at its helm.

I would also like to inform you that a competitive recruitment process has been launched for the selection of a new Executive Secretary at the D2 level. The job opening was launched on 14 September 2020 and will be open to receive applications until 28 October 2020.

And finally, my deepest thanks and appreciation to Tina for her outstanding leadership in achieving formidable milestones for the Secretariat over the years.

Yours sincerely,

Inger Andersen

Executive Director

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 jet1,2, a positive trend in the Southern Annular Mode1,3–6 and an expansion of the Hadley cell7,8. It has been established that these trends were driven by ozone depletion in the Antarctic stratosphere due to emissions of ozone-depleting substances9–11. 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. Because pre-2000 circulation trends have affected precipitation12–14, and potentially ocean circulation and salinity15–17, we anticipate that a pause in these trends will have wider impacts on the Earth system. Signatures of the effects of the Montreal Protocol and the associated stratospheric ozone recovery might therefore manifest, or have already manifested, in other aspects of the Earth system.

Chlorofluorocarbon (CFC) banks from uses such as air conditioners or foams can be emitted after global production stops. Recent reports of unexpected emissions of CFC-11 raise the need to better quantify releases from these banks, and associated impacts on ozone depletion and climate change. Here we develop a Bayesian probabilistic model for CFC-11, 12, and 113 banks and their emissions, incorporating the broadest range of constraints to date. We find that bank sizes of CFC-11 and CFC-12 are larger than recent international scientific assessments suggested, and can account for much of current estimated CFC-11 and 12 emissions (with the exception of increased CFC-11 emissions after 2012). Left unrecovered, these CFC banks could delay Antarctic ozone hole recovery by about six years and contribute 9 billion metric tonnes of equivalent CO2 emission. Derived CFC-113 emissions are subject to uncertainty, but are much larger than expected, raising questions about its sources.

The Montreal Protocol on Substances that Deplete the Ozone Layer is a global agreement to protect the Earth’s ozone layer by phasing out the chemicals that deplete it. This phase-out plan includes both the production and consumption of ozone-depleting substances. The landmark agreement was signed in 1987 and entered into force in 1989. 

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