In this episode, I talk with Sarah Smith of the Clean Air Task Force about methane, the greenhouse gas that falls out of the atmosphere more quickly than carbon dioxide but trap a lot more heat while it’s there. We discuss sources of methane pollution, opportunities for reduction, and recent policy developments. Full transcript of Volts podcast featuring Sarah Smith, September 29, 2021(PDF version)David Roberts:Methane is having a moment. Methane — chemical name CH4 — is a fuel. It is the primary ingredient in natural gas, which generates about 40 percent of US electricity and heats about half of US homes. It is also an air pollutant, a precursor to ground-level ozone, which is toxic to humans. And it is also a greenhouse gas, much shorter lived in the atmosphere than CO2, but much more potent while it is there. Methane in the atmosphere comes from leaks along oil and gas infrastructure, from agriculture (primarily cow burps and manure), and from landfills. Rising concern over methane pollution has culminated in the Global Methane Pledge, announced by President Joe Biden’s White House last week, which would have participating countries (which include the EU, the UK, and Mexico) reduce methane emissions at least 30 percent by 2030. This followed the United Nations Environment Program’s Global Methane Assessment in May, which found that substantially and rapidly reducing methane is the only way to meet the international goal of keeping warming under 1.5°C. Clearly, for those of us who haven’t been paying as close attention as we should, it’s time to tune into the methane debate. The Clean Air Task Force has been tracking methane pollution and advocating for reductions for years. So I was eager to talk to Sarah Smith, the head of CATF’s Super Pollutants program, about the basics of methane: where it comes from, how it can be reduced, and the battles over it in US methane policy. (See also: Smith’s op-ed in Canary.)Without further ado, Sarah Smith, welcome to Volts. Thanks for coming.Sarah Smith:   Thank you so much for having me, David.David Roberts:   For those of us who have not been tracking the details of methane as closely as they might: what exactly is methane? Sarah Smith:   Methane is an invisible, odorless gas that is commonly known as the main constituent of natural gas. It has flown under the radar for far too long. It's currently contributing to about half the warming that we're experiencing today.David Roberts: Methane is a greenhouse gas that traps more heat in the atmosphere than CO2, but for a shorter period of time. What is the climate change potential of methane, and how does it differ from CO2?Sarah Smith:  Every pound of methane heats the climate more than 80 times as much as a pound of CO2. But methane only lasts for about a decade in the atmosphere, which is a big opportunity, because quickly reducing the amount of methane in the atmosphere would very quickly slow warming, whereas carbon dioxide is slowly building up over time and takes much longer to reduce.David Roberts: I’ve seen it compared to stock vs. flow. With CO2, if you stock it up in the atmosphere it stays, so you have to worry about the total amount. Methane is a flow problem; it's constantly coming out of the atmosphere. Is it fair to say that if we reduced the addition of methane into the atmosphere to the rate at which it was coming out of the atmosphere, we would basically stabilize its temperature effect? In other words, theoretically, there is some level of methane emissions at which you're not making things warmer.Sarah Smith:Exactly, and that's the goal: to get back to those pre-industrial concentrations of methane by ensuring that less methane is being added than removed.David Roberts: It is startling that methane has caused half of historical climate warming thus far. How was that discovered, and how did we not know it for so long?Sarah Smith:I ask myself that question all the time. The latest report from the Intergovernmental Panel on