Executive Summary

ANDREAS ENGEL; MATT RIGBY; JAMES BURKHOLDER; RAFAEL PEDRO FERNÁNDEZ; LUCIEN FROIDEVAUX; BRAD HALL; RYAN HOSSAINI; TAKUYA SAITO; MARTIN VOLLMER; BO YAO

Scientific Assessment of Ozone Depletion: 2018

World Meteorological Organization

Lugar: Ginebra; Año: 2018; p. 1 - 70

The Assessment documents the advances in scientific understanding of ozone depletion reflecting the thinking of the many international scientific experts who have contributed to its preparation and review. These advances add to the scientific basis for decisions made by the Parties to the Montreal Protocol. It is based on longer observational records, new chemistry-climate model simulations, and new analyses. Highlights since the 2014 Assessment are: Actions taken under the Montreal Protocol have led to decreases in the atmospheric abundance of controlled ozone-depleting substances (ODSs) and the start of the recovery of stratospheric ozone. The atmospheric abundances of both total tropospheric chlorine and total tropospheric bromine from long-lived ODSs controlled under the Montreal Protocol have continued to decline since the 2014 Assessment. The weight of evidence suggests that the decline in ODSs made a substantial contribution to the following observed ozone trends: The Antarctic ozone hole is recovering, while continuing to occur every year. As a result of the Montreal Protocol much more severe ozone depletion in the polar regions has been avoided. Outside the polar regions, upper stratospheric ozone has increased by 1?3% per decade since 2000. No significant trend has been detected in global (60°S?60°N) total column ozone over the 1997?2016 period with average values in the years since the last Assessment remaining roughly 2% below the 1964?1980 average.