Twenty Questions and Answers About the Ozone Layer

Twenty Questions and Answers About the Ozone Layer



5 May 2015

A new publication, Twenty Questions and Answers About the Ozone Layer, presents complex science in a straightforward manner. It complements the 2014 Scientific Assessment Report of Ozone Depletion by WMO and the U.N. Environment Programme.

Global ozone depletion is no longer increasing, and initial signs of recovery of the ozone layer have been identified. This is thanks to the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer.

 As a result of the broad compliance with the Protocol and industry’s development of “ozone-friendly” substitutes for the now-controlled chemicals, the total global accumulation of Ozone Depleting Substances (ODSs) has slowed and begun to decrease. With continued compliance, substantial recovery of the ozone layer is expected by the middle of the 21st century.

Twenty Questions and Answers About the Ozone Layer is meant to contribute to a broad understanding of the relationship between ozone depletion, ODSs, and the Montreal Protocol. Most questions and answers are updates of those presented in previous Ozone Assessments, and a few have been expanded to address newly emerging issues.

The questions address the nature of atmospheric ozone, the chemicals that cause ozone depletion, how global and polar ozone depletion occur, the extent of ozone depletion, the success of the Montreal Protocol, and the possible future of the ozone layer. Computer models project that the influence on global ozone of greenhouse gases and changes in climate will grow significantly in the coming decades and exceed the importance of ODSs in most atmospheric regions by the end of this century. Ozone and climate are indirectly linked because both ODSs and their substitutes are greenhouse gases and contribute to climate change. The Antarctic ozone hole has recently been shown also to have a direct effect on Southern Hemisphere surface climate during summer.

A brief answer to each question is first given in blue; an expanded answer then follows. The answers are based on the information presented in the 2014 and earlier Assessment reports as well as other international scientific assessments. The reports and the answers provided were prepared and reviewed by a large number of international scientists who are experts in different research fields related to the science of stratospheric ozone and climate.

The reports are conducted under the auspices of WMO and UNEP and are co-sponsored by NASA, the U.S. National Oceanic and Atmospheric Administration, and the European Commission.

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