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Ozone Layer

The depletion of stratospheric ozone, driven primarily by the presence of chlorine and bromine in the stratosphere, is a significant health risk to human and animal life. The ozone layer has started to recover following the Montreal Protocol of 1987 [1], which banned many ozone-depleting substances, but full recovery is not expected until around 2070 [5].

Ozone-depleting substances in the stratosphere, in the equivalent of parts per billion of chlorine. Stratospheric ozone is depleted mainly by chorine and bromine. Concentration of these substances peaked in 2000 but remains well above natural levels. Source: Goddard Space Flight Center [1].

As of 2016, world emissions of ozone-depleting substances are estimated as follows. Evidence suggests the unreported increase in CFC-11 emissions, which is illegal under the Montreal Protocol, is coming from Eastern China [3].

Major ozone-depleting chemicals, estimate depletion potential from emissions as of 2016 as reported by the Goddard Center [1], and major sources of emissions as reported by the World Meteorological Association [5]. Not every ozone-depleting chemical is listed.

Based on a social cost of CFC-11 of $618 (2020 dollars) reported in 1992 [2], current world ozone-depleting emissions from human activity inflict $86-199 billion of damages per year. Separately, the Montreal Protocol has been estimated to prevent $51 billion (2020 dollars) in damages per year from 1987 to 2060 to human health, agriculture, fisheries, and materials [4].

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[1] Goddard Space Flight Center. "NASA Ozone Watch". National Aeronautics and Space Administration. Accessed April 27, 2020.

[2] Kopko, W. "Analysis of Overall Environmental Impact from CFC Alternatives in Commercial Building Cooling Applications". 1992.

[3] Rigby, M. et al. "Increase in CFC-11 emissions from eastern China based on atmospheric observations". Nature 569, pp. 546–550. May 2019.

[4] United Nations Environment Programme. "The Montreal Protocol and the Green Economy: Assessing the contributions and co-benefits of a Multilateral Environmental Agreement". 2012.

[5] WMO (World Meteorological Organization). Scientific Assessment of Ozone Depletion: 2018. Global Ozone Research and Monitoring Project–Report No. 58, 588 pp., Geneva, Switzerland. 2018.