ESRL Quarterly Newsletter - Spring 2010

HFC-23 Emissions on the Rise

Policy experts take note of increase in the potent greenhouse gas

Collecting firn air in Antarctica.

Collecting firn air in Antarctica.

Three times in the last decade, ESRL scientists and colleagues traveled to Antarctica, drilled hundreds of feet into dense snow, and extracted air samples that they hoped would give them insight into atmospheric changes.

Air trapped in compressed snow (“firn”) contains a record of atmospheric composition changes, and ESRL's Stephen Montzka (Global Monitoring Division) and David Fahey (Chemical Sciences) and their colleagues were especially interested in the powerful greenhouse gas, HFC-23. There have been international efforts to control emissions of the gas, which lasts 300 years in the atmosphere, and which is thousands of times more efficient (per molecule) at trapping heat than is carbon dioxide.

Still, HFC-23 emissions are up, the researchers reported Jan. 29 in Geophysical Research Letters.

“Without the international effort to reduce emissions of HFC-23, its emissions and atmospheric abundance would have been even larger,” Montzka said. “As it was, emissions averaged over 2006-2008 were about 50 percent above the 1990-2000 average.” Although HFC-23, also known as trifluoromethane, is not itself an ozone-depleting gas, it is linked to the issue of stratospheric ozone depletion in another way. HFC-23 is released into the atmosphere primarily during the production of another chemical, HCFC-22, an ozone-depleting gas used in refrigeration, heat- and chemical-resistant products, and more. Today, HFC-23's overall contribution to warming is small, relative to other greenhouse gases, but since only a portion of the processes that generate HFC-23 are restricted, scientists are keeping tabs on it.

The United Nations Framework Convention on Climate Change is concerned enough about this greenhouse gas that it has facilitated the destruction of HFC-23 in developing countries since 2003. Developed countries have also reported significant drops in HFC-23 emissions after 2000. Montzka et al. concluded that increasing HFC-23 emissions and atmospheric concentrations in recent years can be attributed primarily to rapidly increasing production of the ozone-depleting gas HCFC-22 in developing countries.

Montzka presented the team's research to a Montreal Protocol “Stakeholder” meeting in late January, hosted by the Environmental Protection Agency (EPA) and the State Department. Parties to the Montreal Protocol, including the United States, set international policy on substances that deplete Earth's protective ozone layer.

The meeting drew about 100 people from diverse sectors, from industry groups to environmental organizations, said EPA's Cindy Newberg, Chief of the Alternatives & Emissions Reduction Branch (Stratospheric Protection Division). Discussion focused on possible policies to control HFCs under the Montreal Protocol, and policies regarding the destruction of ozone-depleting compounds.

“This was a great forum for Steve to present his findings. Many people have been thinking that HFC-23 is a problem, but his group actually went out and did the research,” Newberg said. “Everyone was interested in connecting the science to potential policy options.”

Last year, the United States and many other countries jointly declared a commitment to phase down the production and consumption of HFCs, in general. Without further regulation, HFC use is projected to grow, as countries phase out the use of ozone-depleting substances, and turn to HFCs as replacements.

There will be a Montreal Protocol working group meeting in Bangkok in June, and the 22nd meeting of the Parties is tentatively scheduled for October in Africa—where many anticipate additional discussions on potential HFC controls.