The methane in our atmosphere comes from natural biogenic (plants, animals) and fossil sources. By telling the difference we can know how much we humans are responsible for. It matters because methane is a potent greenhouse gas, second only to CO2. Previous “bottom-up” estimates came from multiplying the number of sources (livestock, natural gas operations, landfills) by their likely emissions. Robert McSweeney at Carbon Brief describes a new … [Read more...]