As the curtain rises tomorrow in Cancún, Mexico, on the next round of international talks on climate change, expectations are low that the delegates will agree on a new treaty to reduce emissions that contribute to global warming. They were unable to do so last year in Copenhagen, and since then the negotiating positions of the biggest countries have grown even further apart.
Yet it is still possible to make significant progress. To give these talks their best chance for success, the delegates in Cancún should move beyond their focus on long-term efforts to stop warming and take a few immediate, practical actions that could have a tangible effect on the climate in the coming decades.
The opportunity to make progress arises from the fact that global warming is caused by two separate types of pollution. One is the long-term buildup of carbon dioxide, which can remain in the atmosphere for centuries. Diplomacy has understandably focused on this problem because, without deep cuts in carbon dioxide emissions, there can be no permanent solution to warming.
The carbon dioxide problem is hard to fix, however, because it comes mainly from the burning of fossil fuels, which is so essential to modern life and commerce. It will take decades and trillions of dollars to convert all the world’s fossil-fuel-based energy systems to cleaner systems like nuclear, solar and wind power. In the meantime, a fast-action plan is needed.
But carbon dioxide is not the only kind of pollution that contributes to global warming. Other potent warming agents include three short-lived gases — methane, some hydrofluorocarbons and lower atmospheric ozone — and dark soot particles. The warming effect of these pollutants, which stay in the atmosphere for several days to about a decade, is already about 80 percent of the amount that carbon dioxide causes. The world could easily and quickly reduce these pollutants; the technology and regulatory systems needed to do so are already in place.
Take methane, for example, which is 25 times more powerful than carbon dioxide in causing warming. It is emitted by coal mines, landfills, rice paddies and livestock. And because it is the main ingredient in natural gas, it leaks from many older natural-gas pipelines. With relatively minor changes — for example, replacing old gas pipelines, better managing the water used in rice cultivation (so that less of the rice rots) and collecting the methane emitted by landfills — it would be possible to lower methane emissions by 40 percent. Since saved methane is a valuable fuel, some of this effort could pay for itself.
Unfortunately, the accounting systems used in climate diplomacy are cumbersome and offer relatively few incentives for countries to make much effort to control methane.
Big cuts are also possible in hydrofluorocarbons, or HFCs, many of which are used as refrigerants in air-conditioners and other cooling systems. The most troubling of the short-lived HFCs were invented to replace chlorofluorocarbons, refrigerants that were thinning the ozone layer in the upper atmosphere, and were also a major warming agent. Chlorofluorocarbons were regulated under the Montreal Protocol starting in 1987.
The warming effect of these HFCs is at least 1,000 times that of carbon dioxide. Unless they are regulated as chlorofluorocarbons have been, their warming effect will increase substantially in the coming decades.
Shifting from HFCs to substitutes that are 100 times less potent as climate warmers could offset nearly a decade’s increase in warming that is expected from rising emissions of carbon dioxide. The delegates in Cancún would need only to ask that the Montreal Protocol take on the further authority to regulate HFCs.
From a political point of view, the most appealing greenhouse emissions to reduce are ozone and soot, because they contribute so much to local air pollution. After all, people everywhere care about the quality of the air they breathe and see — even if most of them are not yet very worried about global warming. A desire to clean up the air is a rare point of commonality between developing and industrialized nations.
Ozone, which is formed in the lower atmosphere from carbon monoxide, methane and other gases emitted by human activity, is a particularly hazardous component of urban smog. And every year it causes tens of billions of dollars in damage to crops worldwide. So pollution restrictions that reduce ozone levels, especially in the rapidly growing polluted cities of Asia, could both clear the air and slow warming.
Soot likewise offers an opportunity to marry local interests with the global good. A leading cause of respiratory diseases, soot is responsible for some 1.9 million deaths a year. It also melts ice and snow packs. Thus, sooty emissions from Asia, Europe and North America are helping to thin the Arctic ice. And soot from India, China and a few other countries threatens water supplies fed by the Himalayan-Tibetan glaciers.
New air pollution regulations could help reduce soot. Such laws in California have cut diesel-soot emissions in that state by half. In China and India, a program to improve power generation, filter soot from diesel engines, reduce emissions from brick-making kilns and provide more efficient cookstoves could cut the levels of soot in those regions by about two-thirds — and benefit countries downwind as well.
Reducing soot and the other short-lived pollutants would not stop global warming, but it would buy time, perhaps a few decades, for the world to put in place more costly efforts to regulate carbon dioxide. And it would help the major economies demonstrate credibility on climate change, which has been in short supply in the diplomatic talks so far.
The impasse that was evident in Copenhagen last year and is likely to reappear in Cancún arises in part from the inability of China, India, Europe and the United States to show that they are adopting practical measures to slow climate change. Agreeing on a shared strategy to curtail short-lived pollutants would be a good way for all of them to start.
Credibility is especially important for the United States. It can already offer the world much of the technology and regulatory expertise that will be needed to reduce short-lived pollutants, particularly ozone and soot. Some American efforts are under way to share these technologies, including a program to help provide better cookstoves for people in developing countries. By making such programs more visible and demonstrating that they deliver tangible results, and by establishing a realistic plan for cutting its own emissions at home, the United States could show that it is serious about addressing climate change.
For too long, overly ambitious global climate talks have focused on the aspects of global warming that are hardest to solve. A few more modest steps, with quick and measurable effects, are a better way to proceed.
Veerabhadran Ramanathan, a professor of atmospheric physics at the Scripps Institution of Oceanography and David G. Victor, a professor at the School of International Relations and Pacific Studies at the University of California, San Diego and the author of the forthcoming Global Warming Gridlock.