The work could have bearing on future energy production in the gulf, as decisions about expanding oil and gas harvesting depend on calculations of the climate impact.

While a gap between reported and measured methane emissions in the basin has been noted in the past, this study is believed to be the first to quantify methane and carbon dioxide emissions and identify the main culprits. It turns out older platforms located closer to land emit far more methane than is reported in government inventories.

Simple steps could go a long way in mitigating those releases, the researchers say.

To conduct their atmospheric measurements, the researchers flew upward and downward in a cylindrical pattern around the platforms and measured amounts of both carbon dioxide and methane being released. They combined aircraft measurements with all previous field surveys to gather the largest sample size of Gulf of Mexico platform GHG emissions. Their observations quickly put a spotlight on certain oil and gas producing operations.

"What we found is that a certain type of shallow water platform had large methane emissions that elevated total greenhouse gas emissions for the entire Gulf of Mexico," said Eric Kort, U-M associate professor of climate and space sciences and engineering, principal investigator of the F³UEL project and corresponding author of the study published in the Proceedings of the National Academy of Sciences.