World leaders are working to reduce greenhouse gas emissions, but it's unclear just how much we're emitting. In the U.S., the Environmental Protection Agency (EPA) has a new program to track these emissions, but scientists are reporting that it vastly underestimates methane emissions from the growing natural gas industry.

Their findings, published in two papers in the ACS journal Environmental Science and Technology, could help the industry clamp down on "superemitter" leaks.

Allen L. Robinson and colleagues note that the primary component of natural gas is methane, a greenhouse gas more potent than carbon dioxide.

The EPA estimates that nearly one-quarter of methane emissions related to human activities comes from producing natural gas, processing it and getting it into the homes of millions across the country. But the agency based its estimate on data from 20 years ago. Robinson's team wanted to see if more recent changes in the industry and technology could further refine the numbers.

The researchers discovered that a small fraction of facilities that collect, process and compress natural gas are responsible for a disproportionately high percentage of methane emissions.

They also found that the EPA's new reporting program doesn't account for superemitters -- sites that leak or vent large amounts of methane -- or some equipment and operating modes that are major sources of the gas. They conclude that the program could be missing almost two thirds of the methane emissions from the natural gas system.