Correction appended.

The Group of Eight joined an international coalition to curb the rise of highly potent greenhouse gases and black carbon at the group's annual meeting last week at Camp David in Maryland.

In the shadows of negotiations on Europe's deepening debt crisis, the G-8 nations -- the United States, Canada, the United Kingdom, Japan, Italy, Russia, France and Germany -- agreed to work toward cutting methane, black carbon and fluorinated gases. These pollutants stay a short time in the atmosphere but can yield thousands of times the global warming power of carbon dioxide -- the most common greenhouse gas and contributor to climate change.

Nevertheless, short-lived climate forcers are responsible for at least 30 percent of current global warming, said David Turk, a counselor to U.S. Special Envoy for Climate Change Todd Stern. While CO2 mitigation remains the focus of climate policy, cutting methane, black carbons and hydrofluorocarbons (HFCs) can achieve a lot with less effort.

"When it comes with those statistics, the impetus was there," Turk said.

The Climate and Clean Air Coalition for Reducing Short Lived Climate Pollutants (CCAC), announced in February by Secretary of State Hillary Rodham Clinton, has grown from six nations to 15, plus the World Bank, the U.N. Environment Programme and the European Commission (ClimateWire, Feb. 17). The coalition signifies a "general willingness" to work together on short-lived climate forcers, but members can choose which particular initiatives and pollutants on which to focus, said Turk.

The G-8 announcement adds weight to the U.S. support behind curbing short-lived climate forcers, said Durwood Zaelke, president of the Institute for Governance and Sustainable Development. After Clinton's announcement, President Obama mentioned short-lived climate forcers in his statement at the North American Leaders' Summit in April.

The G-8 agreement includes Russia -- whose agricultural burning practices deposit a significant amount of black carbon on Arctic snow and speed the rate of snowmelt -- to commit to the issue.

"It's a huge step forward to have heads of government, rather than environmental ministers," making commitments, said Zaelke.

Using a protocol that works

The $15 million effort announced three months ago will fund projects to reduce methane emissions from agriculture or oil and gas operations; HFC leaks from refrigerators; and black carbon, or soot, from diesel engines and wood-burning cookstoves.

The World Bank has invested about $12 billion in projects that contribute to reductions in short-lived climate forcers, as well, said Zaelke, according to calculations by the bank's vice president for sustainable development, Rachel Kyte.

Examples of promising projects include methane capture systems on landfills, capture systems at oil and natural gas extraction wells, the distribution of clean-burning cookstoves that do not release black soot into the atmosphere, and the substitution of more benign alternatives for refrigerant gases with thousands of times the global warming potential of CO2.

The G-8 commitment comes just a month before the Group of 20 meeting in Los Cabos, Mexico, and the United Nations' Rio+20 meeting on sustainable development in Rio de Janeiro.

It also takes place in the 25th anniversary year of the Montreal Protocol, a treaty to phase out gases that deplete the ozone layer. Climate change advocates have begun looking to the protocol, widely considered one of the most successful environmental agreements, as a way to lower emissions of the climate-warming HFCs, which come from leaks in refrigeration systems.

HFCs were widely used as replacements for the ozone-depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) (ClimateWire, Nov. 18, 2011).

"If you want to take a big bite out of the HFCs, you have to do it out of the Montreal Protocol," Zaelke said. "The question is, will this be the year? Will the 25th anniversary be the year?"

Correction: The original version of this story stated that the coalition includes 13 countries. The total is 15 countries. The European Commission, not the European Union, is a partner.