The amount of methane entering the atmosphere is a point of contention and there is no universal, standardised way of measuring it. Tracking the emission of this greenhouse gas in the US is the responsibility of the EPA. The EPA uses models which take a “bottom-up” approach; their inventory is found by counting the well heads, storage tanks, pipeline and other sources of methane, calculating an average annual release for each source and summing them up.
Other organisations taking a top-down approach, using satellite imaging or atmospheric measurement to calculate the total methane emissions, have results which contradict the EPA models and say that these are underestimating the amount of methane by as much as half.
“Top-down approaches were finding total emissions double the EPA’s emissions, but the reason why was not clear,” said Jeff Rutherford, who has been working on the problem since beginning his PhD in 2018. With his advisor, Professor Adam Brandt...