More Ozone-Destroying CFCs Than Projected Still Entering Atmosphere

Despite a worldwide phaseout of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) under the 1987 Montreal Protocol, these ozone-depleting substances (ODSs) are still being emitted into the atmosphere at rates greater than anticipated, according to a new report by the UN Intergovernmental Panel on Climate Change (IPCC). Moreover, the ozone-friendly, fluorinated substitutes that replaced them, such as hydrofluorocarbons (HFCs), perfluorocarbons, and sulfur hexafluoride, are potent greenhouse gases (GHGs) whose emissions are likely to grow.

The problem stems from a gap between the Montreal Protocol and the 1997 Kyoto Protocol. Although the former regulates production and consumption of ODSs, which also contribute to climate change, it says nothing about emissions, explains Susan Solomon, a senior scientist with the U.S. National Oceanic and Atmospheric Administration and one of the IPCC working group co-chairs who coordinated the report. Meanwhile, the Kyoto Protocol controls GHG emissions, including those from fluorinated gases, but not their production and consumption. Left unregulated are existing stocks or banks of ODSs.

Consequently, a big chunk of the CFCs and HCFCs that still leak into the atmosphere now and will continue to do so over the next decades are uncontrolled releases coming from old equipment, mainly air conditioners, refrigerators, insulating foams in appliances, and building materials. Overall, the report shows that the global warming impact of ODSs and their replacements has declined from about 32% of the total effect in 1990 to about 10% in 2000—a huge success for the Montreal Protocol. However, of that 10%, 65% still comes from CFCs, with HCFCs and HFCs contributing an estimated 20% and 15%, respectively.

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By 2015, CFC emissions are expected to decline to about 10% of the ODS contribution, according to the report. But under a business-as-usual scenario, the IPCC predicts that rising emissions from HFCs and HCFCs will offset these emission reductions. Emissions of CFCs and their replacements could be cut in half by 2015, the IPCC maintains, if governments work to improve containment to prevent leaks, evaporation, and emissions of unintended byproducts; reduce the amounts needed in equipment; promote more end-of-life recovery, recycling, and destruction of substances; use more ammonia and other alternative substances with a lower or negligible global warming potential; and promote emerging technologies that avoid gases that deplete ozone or contribute to climate change."

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http://pubs.acs.org/subscribe/journals/esthag-w/2005/may/science/kc_ozone.html