The Department of the Interior announced a new rule Tuesday to reduce methane waste on public and Indian lands, as part of President Barack Obama’s Climate Action Plan. Methane emissions not only contribute to climate change, but “enough natural gas was lost between 2009 and 2015 to serve more than 6 million households for a year,” the department said.

But the rule may be short-lived. Trump has promised to “scrap the $5 trillion dollar Obama-Clinton Climate Action Plan and the Clean Power Plan and prevent these unilateral plans from increasing monthly electric bills by double-digits without any measurable effect on Earth’s climate.”

Methane, the main ingredient of natural gas, is 34 times stronger at trapping heat than carbon dioxide, and a 2010 report by the Government Accountability Office found that federal and state governments, tribes, and taxpayers lose an estimated $23 million in annual revenue due to methane waste due to flaring, venting, and leaks.

The Obama administration’s window for new environmental rules is closing fast. According to The Wall Street Journal, “Congress can use a little-known law called the Congressional Review Act to nullify rules that have been finalized within 60 days that Congress is in session, a time period that often extends much longer than a couple of months since lawmakers aren’t in session every weekday,” which makes November 20 the unofficial deadline for climate action.