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News & Events - 2018


Executive Summary of the 2018 Scientific Assessment of Ozone Depletion

5 November 2018

The United Nations Environment Program released the Executive Summary of the 2018 scientific assessment of the stratospheric ozone layer today. David Fahey, director of NOAA ESRL Chemical Sciences Division, serves as co-chair of the Scientific Assessment Panel (SAP), along with John A. Pyle (University of Cambridge and the National Centre for Atmospheric Science, UK), Paul Neuman (NASA Goddard Space Flight Center, USA), and Bonfils Safari (University of Rwanda, College of Science and Technology, Kigali, Rwanda).

The Executive Summary summarizes the six scientific chapters of the international ozone assessment, which is prepared by the scientific community every four years in accordance with the United Nations Montreal Protocol on Substances that Deplete the Ozone Layer. This 1987 agreement and its amendments and adjustments protect Earth's ozone layer from depletion by manmade ozone-depleting substances, such as chlorofluorocarbons (CFCs) and halons. The full scientific assessment – the Scientific Assessment of Ozone Depletion: 2018 – is currently in production with an expected release date of 30 December 2018.

Among the findings discussed in the 2018 Executive Summary:

  • Actions taken under the Montreal Protocol have led to decreases in the atmospheric abundance of controlled ozone-depleting substances and the start of the recovery of stratospheric ozone.
  • The Kigali Amendment is projected to reduce future global average warming in 2100 due to hydrofluorocarbons (HFCs) from a baseline of 0.3–0.5 °C to less than 0.1 °C
  • There has been an unexpected increase in global total emissions of CFC-11.
  • Sources of significant carbon tetrachloride emissions, some previously unrecognized, have been quantified.
  • Continued success of the Montreal Protocol in protecting stratospheric ozone depends on continued compliance with the Protocol.

The scientific chapters provide supporting detail for the 2018 assessment's Executive Summary, a component of the full assessment. The 2018 assessment is a two-year endeavor carried out under the auspices of the World Meteorological Organization and the United Nations Environment Programme, with NOAA, NASA, and the European Commission as supporting organizations. It is the product of 200+ scientists and support staff from 32 countries who contribute to its preparation and review. NOAA scientist David W. Fahey helped lead the report as one of four international co-chairs of the scientific panel. Other NOAA federal and Cooperative Institute scientists serve as authors, contributors, chapter editors, reviewers, and coordinating editor.

The ozone assessment contributes to NOAA's mission to provide decision-relevant scientific information on atmospheric issues that pertain to the public welfare. The periodic updates of the "state of understanding" regarding the ozone layer have enabled the countries of the world to avoid harmful effects of increased surface ultraviolet radiation that would have occurred in the absence of the Montreal Protocol. The Montreal Protocol has also had co-benefits for climate, because most ozone-depleting substances are also greenhouse gases.

More information:

UNEP / WMO Joint Press Release: Montreal Protocol assessment reveals healing ozone, untapped potential for climate action

More on the ozone layer from NOAA ESRL

More on ozone-depleting substances from NOAA ESRL

Twenty Questions and Answers About the Ozone Layer: 2014 Update (next update expected early 2019)