As world leaders grapple with how to cut global emissions of carbon dioxide, diplomats in Paris are recording progress in combating other pollutants that scientists believe are contributing powerfully to rising temperatures.
A coalition of governments and private businesses has agreed to take up a series of initiatives to limit so-called “short-lived climate pollutants,” ranging from industrial chemicals used in refrigerators to soot particles given off by diesel engines. While emissions of these pollutants are small compared to carbon dioxide, some are vastly more powerful, pound for pound, in trapping heat in the Earth’s lower atmosphere.
Participants in the efforts say controlling these pollutants could offer a way to slow global warming in the coming decades while giving scientists and policymakers more time to tackle the bigger challenge of curbing carbon-dioxide emissions from fossil fuels.
“This will produce the biggest single piece of climate mitigation in the near term and avoid a half degree Celsius of warming by the end of the century,” Durwood Zaelke, founder of the Institute for Governance and Sustainable Development and an expert in international environmental law, told a news conference Friday at the Paris climate talks. In fighting climate change, “speed matters profoundly,” he said.
Short-lived climate pollutants are so named because they dissipate relatively quickly in the environment — in years or decades, compared to hundreds or thousands of years for carbon dioxide. They include methane, a naturally occurring gas that is also given off in large quantities by oil and gas operations, farms and landfills; common industrial coolants called hydrofluorocarbons, or HFCs; and “black carbon,” which consists mostly of soot particles. When black carbon settles on snow and ice it darkens the surface, drawing more heat from the sun and causing faster melting.
On Friday, officials in Paris announced plans to broaden the Green Freight Action Plan, a coalition of 20 countries and several major corporations, including Volvo and Hewlett Packard, to reduce diesel soot from the transportation sector, especially heavy trucks and cargo ships. Separately, a business group called the Global Food Cold Chain Council announced new steps to cut back on the use of HFCs in commercial and industrial refrigeration. Dozens of U.S. companies are already participating in voluntary measures to speed up the shift from HFCs to alternative chemicals that are safer for the environment. Last month, more than 190 nations agreed in principle to scale back global production of HFCs under the Montreal Protocol, the 1989 accord that banned production of chemicals that damage the Earth’s ozone layer. Details are to be finalized at an international conference in Dubai next year.
“This collaboration is an excellent example of what can be accomplished when all parties work together in good faith to achieve a common goal,” said Stephen Yurek, president of the Air-Conditioning, Heating, and Refrigeration Institute, the U.S. trade association representing refrigerant producers and air-conditioning and refrigeration equipment manufacturers.
Multiple efforts already are underway to limit methane, which currently accounts for about 25 percent of the greenhouse-gas problem, experts say. Environmental and industry groups have launched initiatives to cut down on leaks of methane gas from oil and gas fields, the single biggest source of man-made emissions.
Fred Krupp, president of the Environmental Defense Fund, said reducing such leaks offers a fast way to gain ground in the fight against climate change.
“The higher temperatures get in the short run, the more likely it is that we are going to pass a trigger point that leads to runaway warming,” Krupp said. Cutting methane leaks “gives us an opportunity to minimize that risk,” he said.