Current State of the Ozone Layer

Atmospheric levels of ozone-depleting substances (ODSODSA compound that contributes to stratospheric ozone depletion. ODS include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, hydrobromofluorocarbons, chlorobromomethane, and methyl chloroform. ODS are generally very stable in the troposphere and only degrade under intense ultraviolet light in the stratosphere. When they break down, they release chlorine or bromine atoms, which then deplete ozone. A detailed list (http://www.epa.gov/ozone/science/ods/index.html) of class I and class II substances with their ODPs, GWPs, and CAS numbers are available.) rapidly increased before the implementation of the Montreal Protocol on Substances that Deplete the Ozone Layer and its subsequent revisions and amendments. However, the atmospheric levels of nearly all these substances have declined substantially in the past two decades.

Continued declines in ODS emissions are expected to result in a near complete recovery of the ozone layer near the middle of the 21st century. The long time scale for this recovery is due to the slow rate at which ODS are removed from the atmosphere by natural processes.

Many organizations monitor the status of the ozone layer:

• Scientific Assessment of Ozone Depletion: 2014 

This is the most recent World Meteorological Organization (WMO) and United Nations Environmental Programme (UNEP) assessment. It contains the most up-to-date understanding of ozone depletion and reflects the thinking of over 312 international scientific experts who contributed to its preparation and review. A related document provides Twenty Questions and Answers about the Ozone Layer: 2014 Update.

• Environmental Effects of Ozone Depletion and Its Interactions with Climate Change: 2014 Assessment  

From UNEP, this report highlights the latest data and research into environmental effects of ozone depletion and its interactions with climate change.

• Current Status of the Antarctic Ozone Hole

View a page from the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center's website, which shows weekly updates of the hole.

• National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL)

ESRL's Global Monitoring Division conducts research on the depletion of the global stratospheric ozone layer and Antarctic ozone.

• NOAA Climate Prediction Center Products: Stratosphere

Provides current satellite ozone maps, the ultraviolet UV index bulletin, and other data and images.

• NOAA Satellite and Information Service

Provides live data from satellites that monitor stratospheric ozone and UV radiation.

• WMO Global Atmosphere Watch

Includes information about WMO's atmospheric monitoring and research.

• NASA provides daily images, data, and information from satellite instruments that monitor the ozone layer and the ozone hole, a thinning break in the stratospheric ozone layer. Designation of amount of such depletion as an "ozone hole" is made when the detected amount of depletion exceeds fifty percent. Seasonal ozone holes have been observed over both the Antarctic and Arctic regions, part of Canada, and the extreme northeastern United States.

• National Aeronautics and Space Administration (NASA) Ozone Hole Watch

• United Nations Environment Programme's Ozone Secretariat. This website provides information on the Secretariat for the Vienna Convention for the Protection of the Ozone Layer  , and the Montreal Protocol on Substances that Deplete the Ozone Layer .

• World Ozone and Ultraviolet Radiation Data Centre. Find ozone information from Environment Canada and the WMO. Environment Canada also shares current and time series graphs of ozone and UV radiation over North America .