Carbon dioxide may sit atop the greenhouse gas villain heirarchy, but working to mitigate some other warming agents may present some of the easiest and cheapest climate change targets. A new study published in Science today suggests that a number of measures combating methane and soot -- also known as black carbon -- could cut warming by almost one degree Celsius by 2050.
Methane is a greenhouse gas with far lower concentrations in the atmosphere than CO2 but with a potency more than 20 times as strong. An international group led by Drew Shindell of Columbia University's Earth Institute found that a number of methods to reduce methane emissions could be done on the cheap: these include capturing methane that escapes from coal mines and oil and gas facilities, reducing leakage from pipelines, addressing landfill emissions, and various agricultural restrictions.
Soot, meanwhile, though short-lived in the atmosphere, acts as a warming agent and also negatively impacts human health. Adding filters to diesel vehicles, building and distributing more efficient cookstoves and kilns, and banning the burning of agricultural land would all have a big impact on black carbon's effects.
Taken together, the researchers found that almost a full degree of warming could be avoided by 2050. And not only that, we could also avert between 700,000 and 4.7 million premature deaths due to pollution each year and increase crop yields by as many as 135 million metric tons per year. For methane alone, the benefit of taking one metric ton out of the air sits somewhere between $700 and $5,000, and the cost maxes out at $250 per ton.
A no-brainer, right? Well, sure, but making those things happen isn't just a matter of deciding to do it. Take cookstoves, for example: these are the primary means of cooking for almost 3 billion -- billion with a "b" -- people around the world, and according to the Global Alliance for Clean Cookstoves (supported by the United Nations Foundation), they are responsible for as many as 2 million premature deaths every year. The Alliance wants to upgrade 100 million of the dirty stoves to cleaner versions by 2020. This is an ambitious goal, and it would only represent part of the improvement required by the Science paper to get to that one degree of warming.
Or how about reducing methane leaks from pipelines and oil and gas production facilities? Again, this isn't a matter of flipping a switch. Just in the U.S., enough gas leaks from such infrastructure each year to match the emissions from 35 million cars. Until energy companies have some economic reason to tighten those loose pipe fittings -- say, a carbon tax -- the gas is likely to continue flowing.
Still, Shindell and colleagues' research does provide some hope in the face of an international climate -- so to speak -- that shows only cursory momentum toward limiting carbon dioxide emissions. Their modeling narrowed down 400 possible mitigation strategies, all using existing technologies, to the 14 that would have the most immediate benefit; all 14 involved methane or black carbon. "We have identified practical steps we can take with existing technologies," Shindell said in a press release. "Protecting public health and food supplies may take precedence over avoiding climate change in most countries, but knowing that these measures also mitigate climate change may help motivate policies to put them into practice."
Image via NASA Goddard Space Flight Center: Eliminating agricultural burning would cut black carbon emissions by 7 percent.