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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 2.

Ozone Status

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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.

In 2018, the WMO estimated that stratospheric ozone between latitudes 60 ° S and 60 ° N was 7 Dobson units (DU) below the pre-1970 baseline, above 60 ° N was 50 DU below the baseline, and below 60 ° S was 100 DU below the baseline 2. The total shortfall is about 176 million tons.

Ozone-Depleting Substance Emissiosn

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, though more recent data suggests that this unreported source is now decreasing 4. See our analysis of the environmental impacts of the space industry for consideration of how increased rocket launches might impact the ozone layer.

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Major ozone-depleting chemicals and estimated 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 2. Not every ozone-depleting chemical is listed.

Based on a social cost of CFC-11 of $618/kg (2020 dollars) reported in 1992 5, 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 $3.9 trillion (2022 dollars) in damages per year from 1987 to 2060 to human health, agriculture, fisheries, and materials 6.

Problem:
Ozone Depletion
Solution:
Monitor Unaccounted Sources of Ozone Depletion

Stratospheric Ozone Generation

While the ozone layer will recover on its own if the emission of ozone-depleting substances were to cease, recovery can be accelerated through generation of ozone in the stratosphere, or full concentration can be maintained with generation.

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Cost, in billions of dollars, of generating the 176 million ton ozone layer shortfall. Costs of ozone generators are based on an industrial ozone generator offered by Spartan Environmental Technologies 7. The energy cost is based on Spartan's specs for oxygen-fed system 7 and a levelized cost of electricity of 22.1 cents/kWh, the upper range of an estimated range for residential rooftop solar 8. The lifting cost is based on an analysis of the cost of lifting, via balloons, hydrogen sulfide for solar radiation management 9. The price of oxygen is based on NASA's purchases of liquid oxygen for rocket fuel 10.

References

  1. Goddard Space Flight Center. "NASA Ozone Watch". National Aeronautics and Space Administration. Accessed April 27, 2020. ↩ ↩2 ↩3

  2. WMO (World Meteorological Organization). Scientific Assessment of Ozone Depletion: 2018. Global Ozone Research and Monitoring Project–Report No. 58, 588 pp., Geneva, Switzerland. 2018. ↩ ↩2 ↩3

  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. Park, S., et al. "A decline in emissions of CFC-11 and related chemicals from eastern China". Nature 590, pp. 433-437. February 2021. ↩

  5. Kopko, W. "Analysis of Overall Environmental Impact from CFC Alternatives in Commercial Building Cooling Applications". 1992. ↩

  6. Markandya, A., Dale, N. "The Montreal Protocol and the Green Economy: Assessing the contributions and co-benefits of a Multilateral Environmental Agreement". United Nations Environment Programme. 2012. ↩

  7. Spartan Environmental Technologies. "Ozone Generators Feed Gas Economics". Accessed November 10, 2022. ↩ ↩2

  8. Lazard. "Levelized Cost of Energy". October 2021. ↩

  9. Robock, A., Marquardt, A., Kravitz, B., Stenchikov, G. "Benefits, risks, and costs of stratospheric geoengineering". Geophysical Research Letters 36(19). October 2009. ↩

  10. Webster, I. "How much does NASA pay per kg for hydrogen and oxygen in rocket fuel?". Quora. Accessed November 10, 2022. ↩