Among greenhouse gases, carbon dioxide is the most significant contributor to global warming and therefore, public enemy No. 1 when it comes to stopping the climate crisis.
But methane – the main component in natural gas and an even more effective heat-trapping gas – is a close second. Scientists say that atmospheric methane is now responsible for about 25 percent of the human-caused warming we see today.
Now, a new study finds that methane emissions from fossil fuels are between 25% and 40% larger than past research had estimated, revealing that oil and gas production is contributing far more to warming the planet than previously thought.
The study, published Wednesday in the scientific journal Nature, sheds new light on just how much fossil fuel production and use is changing the atmosphere – and in turn, warming the planet.
But the authors say the findings are not all bad news.
Given that we know where the methane is coming from, they say we can take action to reduce emissions that are warming the planet.
However, the Trump administration is proposing to ease regulations on methane that would no longer require the industry to monitor for and stop leaks.
“This shows a large gap in what we thought was being emitted, and what is likely being emitted,” said Benjamin Hmiel, a post-doctoral associate at the University of Rochester and the study’s lead author. “So, if there’s a larger slice of the pie (of overall methane emissions) under our human agency, that means that we have control over those emissions.”
Methane sources are notoriously hard to track
The methane in the earth’s atmosphere comes from a wide variety of sources but can be divided into two categories: biological and fossil.
Biological methane is released by the decay of plants and animals in environments like wetlands, but also from human activity like cattle farming, landfills and rice fields.
Fossil methane, meanwhile, can seep naturally from underground, or it can be released into the air by human extraction of oil and gas.
Hmiel says methane concentrations in our atmosphere have soared by about 150 percent in the roughly two centuries since the Industrial Revolution. The challenge for researchers was determining how much of that increase is due to human oil and gas production.
“We have a really good understanding of how much methane concentrations have increased in the atmosphere,” said Vasilii Petrenko, a professor in the University of Rochester’s Department of Earth and Environmental Sciences and the study’s principal investigator. “But it’s difficult to track where the increases are coming from for a number of reasons.”
To solve the puzzle, the scientists looked for clues in ancient air bubbles trapped in Greenland’s ice sheet.
By measuring the presence of carbon-14 – a rare radioactive isotope – in the air samples, the scientists were able to determine natural historical levels of fossil methane. Their findings showed that naturally occurring fossil methane levels are actually about 10 times lower than what past research had shown.
From there, the scientists were able to deduce how much of the methane in our atmosphere today is actually coming from fossil fuel extraction by humans, which the study found is between 25% and 40% more than previously thought.
All told, the scientists say their findings show that oil and gas production account for nearly half of all the methane in our air that is attributable to human activity.
Methane has a major impact on global warming
There is not as much methane as carbon dioxide in our atmosphere, but it can have an outsized impact on the global climate, especially in the short term.
Methane in the air breaks down after about nine years, but the gas is incredibly effective at trapping heat – a molecule of methane has a global warming potential that is 20 times greater than carbon dioxide.
“Methane is particularly important as we try to slow the rate of climate change because it’s a strong greenhouse gas over a short time period,” said Denise Mauzerall, an environmental engineering professor at Princeton University, who has studied methane leakage from abandoned oil and gas wells as well as offshore rigs.
Methane has come under the microscope in recent years due to the rising global demand for natural gas, which is replacing coal in many parts of the world as a fuel for generating electricity and heating homes.
Natural gas has been billed as a “bridge fuel” between coal and renewable power sources for its supposed lower environmental impact.
And while burning natural gas produces far less carbon dioxide than coal-fired power generation, the methane emissions associated with natural gas production are a serious problem for the planet.
There have been several reports in recent years suggesting that large amounts of methane emissions from oil and gas activity are seeping into the air unaccounted for.
Last year, a report found that a 2018 blowout at a natural gas platform in Ohio likely released as much methane in 20 days as many countries do in an entire year.
A recent New York Times investigation also found that huge amounts of methane are being released from oil and gas facilities around the US and found that even some abandoned facilities continue leaking long after they’re out of use.