Global emissions of methane, a potent greenhouse gas, are twice current estimates and might well impede international efforts to cap global warming well under the two degree Celsius (3.6 degrees Fahrenheit) ceiling set out in the landmark Paris Agreement that will enter into force this November.
These results from a new study published in the peer-reviewed journal Nature are based on a database 100 times larger than previous ones. The study used a methodology that avoided the debatable assumptions underlying earlier models.
It shows that global emissions of methane from oil and gas production and natural sources combined are 60 to 110 percent higher than current estimates.
It also reveals that methane leaked during the production and use of natural gas, oil and coal is 20 to 60 percent higher than previously thought.
"Both emissions inventories and atmospheric studies have underestimated methane emissions from fossil fuel development," said Stefan Schwietzke, a scientist at the U.S. National Oceanic and Atmospheric Administration (NOAA) and lead author of the study.
Emissions from industry and natural geological sources combined "are 60 to 110 percent greater than current estimates," he said.
The new findings might have serious implications for global efforts to contain global warming.
"Emissions scenarios currently used for climate prediction need to be reassessed taking into account revised values for anthropogenic"-- or human-generated -- "methane emissions," said Grant Allen, a professor at the University of Manchester.
Reaching the UN-backed temperature target might even be more difficult than once thought.
Methane is 28 times more efficient at trapping heat in Earth's atmosphere over a 100-year time span than carbon dioxide.
It is the second largest contributor to global warming after CO2, accounting for about a fifth of accumulated temperature increase since the beginning of the industrial revolution in the mid-18th century.
Most methane seeping into the atmosphere -- up to twice as much as previous estimates, the study found -- comes from human activity.