To Slow Climate Change, Cut Down On Soot, Ozone

An Indian street dweller prepares food on the streets of Kolkata. A growing number of scientists say that reducing black carbon — mostly soot from burning wood, charcoal and dung — would have an immediate and powerful impact on climate.

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MELISSA BLOCK, HOST: One topic that's getting scant attention this election season is climate change. Instead, the economy and social issues are front and center, but scientists are working as hard as ever to figure out how much the earth is warming and what to do about it. Some now say it's time for a new strategy. As NPR's Christopher Joyce reports, a strategy that gets faster results.

CHRISTOPHER JOYCE, BYLINE: Durwood Zaelke is a grizzled veteran of the climate wars. He was in Kyoto in 1997 when the world's nations drafted a treaty promising to curb warming, and he's watched that promise fizzle while the planet's temperature continues to rise. Zaelke says the Kyoto treaty focused too much on the main greenhouse gas: carbon dioxide.

DR. DURWOOD ZAELKE: I mean, that's like picking a fight with the biggest bully in the schoolyard. You get your lunch money stolen. You get your pants pulled down, and you get sent home humiliated. We've made about that much progress with CO2.

JOYCE: Most CO2 comes from big power plants and factories, the engines of economic development. Few governments have been willing to endanger development with limits on CO2.

Zaelke runs the Institute for Governance and Sustainable Development in Washington, D.C. He says it's time to look for other climate solutions.

ZAELKE: You can't expect one treaty system to address every cause of climate change. It's too complex of a problem.

JOYCE: A growing number of scientists agree. They're focusing less on CO2 and more on other things that warm the planet, especially ozone and black carbon. Black carbon is mostly soot from burning wood, charcoal and dung.

Climate scientist Drew Shindell, with NASA's Goddard Institute for Space Studies, says ozone and soot live in the air for only a few months or years before they degrade or fall to Earth. If you slow or stop producing them, pretty soon the atmosphere will be fairly soot and ozone-free.

PROFESSOR DREW SHINDELL: So these things really have an immediate and quite powerful, in many cases, effect on climate both at global and regional scales.

JOYCE: Carbon dioxide, on the other hand, stays in the atmosphere for much longer. So, curbing CO2 from smokestacks won't show benefits for many decades.

Shindell says cutting ozone and soot could slow warming by half a degree Celsius by 2050.

SHINDELL: By averting a half a degree of projected warming, that's really a substantial portion of whether the planet really goes over two degrees or stays below that.

JOYCE: Two degrees warmer is when most climate scientists say bad things start happening to the planet.

Shindell says there are economic reasons for cutting ozone and soot, as well. For example, ozone is created when methane gets into the atmosphere. Methane is essentially natural gas; it escapes from coal mines, livestock waste ponds and pipelines. It's valuable, and capturing it saves money. Also, ozone damages commercial crops and causes smog. As for soot, it causes respiratory disease and millions of premature deaths.

SHINDELL: If you factor in the air quality benefits and their large effects on health, then you find the reductions are really giving you benefits.

JOYCE: Benefits that outweigh the costs.

Shindell bases his calculations on wide-ranging assumptions about global health and economic gains, as well as what it would all cost. The numbers vary widely and are likely to be questioned. But the study does confirm others that say ozone and soot should be added to CO2 on the climate hit list.

And climate activist Durwood Zaelke says that unlike carbon dioxide, the tools to reduce these pollutants are familiar.

ZAELKE: We have laws and we have institutions in most countries that already know something about controlling this. We already know the technology. We already know how to do it.

JOYCE: And it wouldn't take an international treaty to do it, either.

Shindell's research appears in the journal Science.

Christopher Joyce, NPR News.

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