Most efforts to slow the impact of global warming have focused on reducing carbon emissions, because, according to the EPA, they are the most dominant and the fastest growing greenhouse gas (GHG). But CO2 is only one of several greenhouse gases, which also include methane, nitrous oxide, and fluorinated gases, such as hydrofluorocarbons, and soot. A team of scientists led by NASA Goddard’s Drew Shindell (who also works at Columbia’s Earth Institute), in an article published in this month’s issue of Science, suggest that an easier and possibly more effective approach, at least in the short term, would be to focus on methane and soot. Why? Because these two pollutants are both fast acting, so reducing their presence in the atmosphere can have a more immediate impact on the overall GHG concentration. If a two degree Celsius increase in average global temperature is seen as the cliff that we are rapidly driving towards, focusing on methane and soot might actually help to slow us down more quickly than our current approach, which focuses on CO2. Not only that, but according to the paper’s title, Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security, reducing these two pollutants, could also realize additional benefits.
According to the study, adapting these measures could reduce warming between now and 2050 from 2.2 degrees to 1.3 degrees Celsius.
Starting from the premise that reducing these two pollutants would rapidly mitigate climate risk, the team evaluated roughly 400 emission control measures and found 14 that could reduce either methane or soot in a cost-effective manner, using existing technology.
Many of these, such as banning the burning of agricultural land, capturing methane from landfills and coal mines, fixing leaky pipelines, putting filters on cook stoves and diesel engines, and modifying agriculture practices for rice paddies and manure collection — are already being used effectively in many places.
Not surprisingly, these results were met with an enthusiastic response from people close to the oil industry. It doesn’t take a huge leap of imagination to see that they will quickly begin using this analysis as a crowbar to start prying up efforts to reduce CO2. John D. Graham, who oversaw regulations at the Office of Management and Budget for the George W. Bush administration, said, “This is an important study that deserves serious consideration by policy makers as well as scientists.”
Well, it may be, especially considering the health impacts, which would come about largely as reduced air pollution levels, primarily from soot. Dramatically reducing soot levels could save as many as 4.7 million lives each year worldwide. Two million people die each year, mostly in Africa, from dirty cook stoves. There could also be agricultural benefits, as soot tends to divert rainfall, causing uneven moisture distribution, flooding and drought. But it is essential to point out at the outset that this does not mean that we should stop trying to reduce CO2 emissions. That would be a big mistake.
Carbon dioxide is still the No. 1 cause of man-made global warming, accounting for 48 percent of the problem. Soot and methane combined account for 30 percent. They do tend to be shorter acting, though, which means that we will see the results of mitigation sooner. The smart strategy is to focus on both long term and short term impacts. The problem is far too serious for a half-hearted solution.
The results await the response of the broad scientific community. I expect there will be a certain amount of controversy. A number of the scientific studies described in the review by Skeptical Science that I covered earlier this week found that aerosols, a category of emissions that includes soot, actually contribute to global cooling, by blocking out sunlight and reducing the amount of solar radiation that reaches the Earth. If that’s true, then aggressively curtailing it could have some warming effect. Going after methane, however has no apparent downside.
[Image credit:yeimaya:Flickr Creative Commons]
RP Siegel, PE, is the President of Rain Mountain LLC. He is also the co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues including energy, food, and water. Now available on Kindle.
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