Eric Kort was looking for methane when he and his team flew a NOAA Twin Otter aircraft over the Bakken formation in May, 2014.
What the University of Michigan climate researcher found was ethane. Lots and lots of ethane.
Kort says the air sample data he collected has solved a mystery. Wwhat caused global ethane emissions to rise between 2009 and 2014, after a significant decline prior to 2009?
"We found that the Bakken Shale was emitting roughly 2% of total global emissions of ethane," says Kort. "Which would be an increase from a very low emissions rate in the early 2000s, before the rapid expansion of oil and gas development in that area."
The Bakken Formation is part of a 200,000 square mile basin that lies under parts of North Dakota and Montana in the U.S., as well as Saskatchewan and Manitoba in Canada.
Oil and gas activity in the Bakken oil field jumped sharply between 2005 and 2014, and Kort says the material in the field happens to contain more ethane than methane.
Ethane is a gas linked primarily to ozone formation, although it also contributes to global warming, and methane, another byproduct of oil and gas drilling, is linked primarily to global warming.
Ozone at the surface level of the earth can exacerbate asthma and cardiovascular diseases.
Kort says there are likely other oil fields with lots of ethane in them which contributed to the global spike, including the Eagle Ford in Texas.
Kort's study, "Fugitive emissions from the Bakken shale illustrate role of shale production in global ethane shift" was published in Geophysical Research Letters.