Research indicates that methane and ethane emissions from oil production may be much higher than previous estimates indicated. The largest discrepancy is for emissions released from 1980 to 2012.

Lena Höglund-Isaksson, a researcher from the International Institute for Applied Systems Analysis (IIASA), developed a methodology for calculating the amount of methane and ethane released while drilling for oil. This methodology incorporates differing oil production technologies prevalent in different oil producing regions.

Flaring at a well site.Previous estimates were based on a direct measurements from North American oil fields and extrapolating those measurements worldwide. Typically, North American oil producers capture almost all of the gases released by oil well drilling. Unrecovered gas is flamed off or vented. In other parts of the world, producers vent larger quantities of gas directly into the atmosphere, the research says.

Höglund-Isaksson’s study estimated global emissions for the 1980-2012 period. She estimated methane and ethane emissions from over 100 countries, using multiple country-specific data points. Her research also incorporated satellite images of gas flaring and atmospheric ethane measurements. Ethane is easier to attribute to oil and gas production activities than methane.

Research results revealed that, particularly in the 1980s, global methane emissions were as much as double the originally reported levels. The Russian oil industry in particular contributes a large fraction of global emissions, she says. When this industry declined in the 1990s, global methane levels also declined.

Since 2005, atmospheric methane levels have stabilized, the research say, likely due to increased shale gas production and more general use of methane recovery systems.