Fossil Fuels Release More Methane Than Originally Thought

By Kevin Ritchart

The use of fossil fuels releases far more methane into the atmosphere than scientists originally thought.

Recent research, published earlier this year in Nature, suggests that as much as 25 to 40 percent more methane enters the environment from coal and natural gas emissions, which makes efforts to reduce climate-warming emissions even more important.

Like carbon dioxide, methane is a greenhouse gas. But the impacts of these gases are not the same. Methane warms the atmosphere more than carbon dioxide does. Methane stays around for approximately 10 to 20 years. Carbon dioxide can linger for hundreds of years.

“So the changes we make to our (methane) emissions are going to impact the atmosphere much more quickly,” said Benjamin Hmiel, an atmospheric chemist at the University of Rochester in New York.

Looking Back

In the 1900s, coal mining, natural gas, and other fossil fuel sources raised methane levels in the atmosphere. Those emissions began falling early in this century. However, beginning in 2007, methane began to rise once again. Recently, it’s reached levels not recorded since the 1980s.

What’s causing the buildup in recent years isn’t completely clear, but previous studies pointed to microbial activity in the wetlands. Other sources might include more cow burps and leaky pipelines. Methane also may be breaking down at a lower rate in the atmosphere.

“If methane emissions keep rising, meeting global goals to lower greenhouse gases will be hard,” said Euan Nisbet, a geochemist at Royal Holloway, University of London.

Looking Ahead

Nisbet also points out that identifying how much methane the oil and gas industry releases could help scientist calculate realistic targets for reduction in the future.

Previously, researchers believed that geological sources, both human and natural, emit from 172 to 195 teragrams (1.1 billion short tons) each year. They have estimated that natural sources released from 40 to 60 teragrams of methane each year.

New studies of ice cores, however, suggest that natural sources produce far less methane than previously believed. With a more accurate accounting of methane released by the fossil fuel industry, scientists might be able to identify how much methane human activities are really releasing in the atmosphere.