A report titled Scientific Assessment of Ozone Depletion 2014 was released on 10 September 2014. The report has been prepared by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO). The report revealed that the ozone layer is well on track to recovery in the next few decades.
Highlights of the Report
• Actions taken under the Montreal Protocol on Substances that Deplete the Ozone Layer in 1986 are enabling the return of the ozone layer to benchmark 1980 levels.
• The Montreal Protocol and associated agreements have led to decreases in the atmospheric abundance of gases, such as CFCs (chlorofluorocarbons) and halons, once used in products such as refrigerators, spray cans, insulation foam and fire suppression.
• Total column ozone declined over most of the globe during the 1980s and early 1990s. Since 2000, it has remained relatively unchanged, but there are recent indications of its future recovery.
• The Antarctic ozone hole continues to occur each spring and it is expected to continue occurring for the better part of this century given that ozone depleting substances persist in the atmosphere, even though their emissions have ceased.
• The Arctic stratosphere in winter or spring 2011 was particularly cold that led to large ozone depletion as expected under these conditions.
• The Montreal Protocol has made large contributions toward reducing global greenhouse gas emissions.
• In 1987, ozone-depleting substances contributed about 10 gigatonnes of CO2-equivalent emissions per year. The Montreal Protocol has now reduced these emissions by more than 90 percent.
• The decrease in ozone-depleting substances is about five times larger than the annual emissions reduction target for the first commitment period (2008-2012) of the Kyoto Protocol on climate change.
• Hydrofluorocarbons (HFCs) currently contribute about 0.5 gigatonnes of CO2-equivalent emissions per year. These emissions are growing at a rate of about 7 percent per year. Though HFCS do not harm the ozone layer but many of them are potent greenhouse gases.
• The annual Antarctic ozone hole has caused significant changes in Southern Hemisphere surface climate in the summer due to cooling of the lower stratosphere there is associated impacts on surface temperature, precipitation, and the oceans.
• In the Northern Hemisphere, where the ozone depletion is smaller, there is no strong link between stratospheric ozone depletion and tropospheric climate.
• The concentrations of CO2, methane and nitrous oxide are the three main long-lived greenhouse gases in the atmosphere which will tend to increase global ozone levels.
What: Released by UNEP and WMO
When: 10 September 2014