Why methane emissions, and why now? The scientific basis DAVID ALLEN , University of Texas at Austin Gertz Regents Chair in Chemical Engineering, and the Director of the Center for Energy and Environmental Resources
M
ethane, the major constituent of natural gas, is a greenhouse gas. Methane concentrations in the
atmosphere, like the concentrations of other greenhouse gases, have been increasing. The Intergovernmental Panel on Climate Change (IPCC) has estimated that the level of methane in the atmosphere was 722 ± 25 parts per billion (ppb) in 1750, prior to the start of the industrial revolution. Recent measurements from the US National Oceanic and Atmospheric Administration indicate that global average methane concentrations had risen to 1893 ppb in 2021, up from 1873 ppb a year earlier. Increased concentrations of methane are causing increased warming (radiative forcing) of the atmosphere. The most recent IPCC assessment increases in atmospheric methane concentrations between 1750 and 2011, was about 17% of the warming due to increased concentrations of all greenhouse gases. Not all of the warming due
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G L O B A L VO I C E O F G A S
JUNE 2021
PHOTO: WOODSIDE
concluded that additional radiative forcing, due to
