This is in direct opposition to last week’s study from New Zealand’s National Institute of Water and Atmospheric Research, which blamed agriculture.

In a paper published in the journal Science NIWA concluded that increasing levels of methane since 2007 were most likely due to agricultural practices, and not fossil fuel production as previously thought.

But according to the recent study from KIT’s climate scientists, and published in the Atmospheric Chemistry and Physics journal last week, at least 40% of the post-2007 increase can actually be blamed on oil and gas production, primarily from the US shale revolution.

“The attribution to thermogenic methane from the oil and natural gas industry is based on our vertical measurements of ethane and methane concentrations between the ground and the uppermost layers of the Earth’s atmosphere,” KIT Institute of Meteorology and Climate Research associate professor Ralf Sussmann said.

Apart from thermogenic methane formed within deep rock layers at high temperatures and emitted into the atmosphere as a result of oil and gas production, growing biogenic emissions by anaerobic processes are another cause, he said.

KIT acknowledged that the corresponding contributions from wetlands or animal husbandry are being analysed in parallel by other research teams, such as NIWA, but said the role of oil and gas could not be understated.

Where the NIWA scientists found an increase in methane in the southern hemisphere, primarily from biogenic origins, measurements at the Zugspitze observatory in Germany show a significant correlation between ethane and methane thermogenic emissions from 2007.

Ethane is essential for quantifying the contribution of thermogenic methane, and it is one of the main components of natural gas, just like methane.

“In case of biogenic methane sources, no ethane is produced,” doctoral student Petra Hausmann explained.

From these measurements, the scientists concluded that at least 40% of the worldwide methane concentration increase after 2007 can be attributed to the northern hemisphere oil and gas sector.

Sussmann explained that, while agriculture maybe responsible for more than half of emissions, more than previously expected, hydrocarbon production plays cannot be played down.

Given that most of the oil and gas boom of the last decade has occurred in the US, the study suggests that official estimates of the US Environmental Protection Agency that reports constantly low or even decreasing methane emissions from the oil and natural gas sector in the US during the past ten years are incorrect.

Sussmann said research published in Geophysical Research Letters was based on satellite data that shows an increase in American methane emissions by more than 30% between 2002 and 2014.

That contradicts the EPA’s findings of no significant anthropogenic methane emissions.

According to Sussmann, at least part of these inconsistencies might be explained by the calculation of too small leak rates for the production and use of oil and natural gas as the EPA extrapolates random samples at individual wells sites and power plants for its emissions estimates while KIT uses representative atmospheric background measurements.

“On long-term scales of several decades, natural gas generally is to be expected to have a climate advantage,” Sussmann said.

“On shorter time scales, however, this climate advantage already fails to take effect, if the leak rates of natural gas production exceed a relatively low threshold value of a few percent only [as] the methane leaking into the atmosphere is shorter-lived, but, at the same quantity, has a much stronger greenhouse effect than carbon dioxide.”

While he said more research is needed to explain the discrepancy between official extrapolations and scientific measurements, there is a need to crack down on well emissions, as otherwise gas may not be the climate-friendly alternative to coal combustion on shorter time scales after all.