According to a new study published in the journal Nature, human activity is producing 40 percent more methane than previously estimated by scientists. Methane is a powerful greenhouse gas that can be produced biologically, can seep naturally into the ground or from volcanic eruptions. It is also a powerful by-product of fossil fuel production.
Natural formation and methane produced by human activity contribute a quarter to current global warming. But human activity releases a much higher proportion of these emissions than initially thought, the study found. They found that methane emissions from human activities could be 25 to 40 percent higher than previous estimates.
All of this has one benefit: the findings also suggest a greater chance of controlling how much methane we release. Methane is more effective than carbon dioxide, so cutting it from our global greenhouse gas emissions could have a huge impact. Andrew Rice, an associate professor at Portland State University, said that most human-induced methane leaks inadvertently when producing and transporting natural gas and oil, so improving these systems “could bring us huge benefits.” “
“It’s our responsibility to recognize that at least we can try to make these metrics better quantified by the industry, because I point out that they are largely reluctant to report them. Benjamin Hmiel, the first author, told The Verge.
For the study, Hmiel and his colleagues analyzed measurements of Greenland’s ice core between 1750 and 2013 based on previous data from Antarctica. They used the isotope carbon-14 as a chemical fingerprint to determine whether the methane present in the ice core came from biological sources such as cows and bacteria or from underground sediments.
Before about 1870, biological resources dominated the ice core. But after that period, fossil fuel production began to increase, and the researchers found that methane without any carbon-14 had increased dramatically. In this way, they can estimate what naturally seeped out of the ground before industrialization and compare it to what people are seeing in the atmosphere. These differences are due to human activities.
Previous efforts to quantify methane emissions from human activities have been measured directly at each potential source. Eric Kort, an associate professor at the University of Michigan, said the difficulty in doing so was one reason the findings were “not actually surprising”. Methane emissions from oil, gas and coal activities are often systematically underestimated, he said, in part because they often use averages as emissions, regardless of hardware failures or other errors that lead to accidental leaks.
Hmiel’s method of measuring methane emissions, he said, “is a tough effort, without any joke, and each sample will melt about 1,000 kilograms of ice.” But there is a big limitation: Nuclear bombs and reactors release more carbon-14 into the atmosphere, which interferes with the study’s readings of methane in samples of 1945 or later. For later samples, the study authors had to use computer models to estimate methane emissions from the rest of human activity.
So while the study offers a promising new approach, Rice says, “additional modeling will be required to verify that this approach is accurate.” “