Related Experiment Video
Updated: Nov 18, 2025

Design and Use of a Full Flow Sampling System FFS for the Quantification of Methane Emissions
Published on: June 12, 2016
A decline in global CFC-11 emissions during 2018-2019
Stephen A Montzka1, Geoffrey S Dutton2,3, Robert W Portmann4
1Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA. stephen.a.montzka@noaa.gov.
Abstract:
The atmospheric concentration of trichlorofluoromethane (CFC-11) has been in decline since the production of ozone-depleting substances was phased out under the Montreal Protocol1,2. Since 2013, the concentration decline of CFC-11 slowed unexpectedly owing to increasing emissions, probably from unreported production, which, if sustained, would delay the recovery of the stratospheric ozone layer1-12. Here we report an accelerated decline in the global mean CFC-11 concentration during 2019 and 2020, derived from atmospheric concentration measurements at remote sites around the world. We find that global CFC-11 emissions decreased by 18 ± 6 gigagrams per year (26 ± 9 per cent; one standard deviation) from 2018 to 2019, to a 2019 value (52 ± 10 gigagrams per year) that is similar to the 2008-2012 mean. The decline in global emissions suggests a substantial decrease in unreported CFC-11 production. If the sharp decline in unexpected global emissions and unreported production is sustained, any associated future ozone depletion is likely to be limited, despite an increase in the CFC-11 bank (the amount of CFC-11 produced, but not yet emitted) by 90 to 725 gigagrams by the beginning of 2020.
More Related Videos
09:03Assessment of Methane and Nitrous Oxide Fluxes from Paddy Field by Means of Static Closed Chambers Maintaining Plants Within Headspace
Published on: September 6, 2018
05:58Author Spotlight: Advancing Coral Culture - Creating a Semi-Quantitatively Controlled Microenvironment System to Counter Current Limitations
Published on: July 21, 2023
Related Concept Videos
Global Climate Change
The Carbon Cycle
What is Climate?
Carbon-13 (¹³C) NMR: Overview
Conservation of Declining Populations
Threats to Biodiversity