Environmental advocates are suing federal officials, alleging they approved the expansion of four Western coal mines on public lands without adequately taking their climate impacts into account.

The New Mexico-based group WildEarth Guardians is accusing the U.S.  Department of the Interior of rubber-stamping coal mine expansions in Colorado, New Mexico and Wyoming without comprehensive environmental reviews, according to a lawsuit filed Sept. 15 in the U.S. District Court of Colorado. The Interior department oversees the leasing of public lands for fossil fuel extraction.

“We are seeing a disturbing pattern in the Interior Department, where every time they review a mining approval or a lease, they always come to the same conclusion: the carbon impacts are insignificant,” said Jeremy Nichols, climate and energy program director at WildEarth Guardians. “This is absolutely insane.”

In the official complaint, WildEarth Guardians argues that the review process used by the Interior Department is flawed. The climate impacts of individual mining approvals are considered in isolation, but “they should be taking into account the cumulative impact of all federal coal leasing and mining decisions” during these reviews, Nichols said, citing the National Environmental Policy Act (NEPA).

The carbon footprint for the entire coal program—which accounts for 40 percent of the coal produced in the U.S.—is significant. In 2012, the federal coal program’s greenhouse gas footprint was equivalent to the annual emissions of more than 161 million cars on the road, according to a Center for American Progress report published in March.

The Supply Side of Pollution

Despite the federal coal program’s major carbon footprint, it has so far faced little pressure by the Obama administration. While President Barack Obama has taken many steps to curb the so-called demand side of climate pollution, including reducing power plant emissions with the Clean Power Plan, said Ted Zukoski, an attorney at the nonprofit legal group Earthjustice, he has “turned a blind eye” to the supply side of the pollution, including the coal leasing program.

The Interior Department recently began discussing how to update the federal coal program, hosting a series of public listening sessions across the country this summer. WildEarth Guardians, among other environmental groups, participated in the sessions. This year the agency proposed changes to how royalties for coal are calculated as well as a new rule to better protect community water sources for coal mining; it is unclear whether any additional new rules are being contemplated.

The four mines targeted in the lawsuit—Colorado’s Bowie No. 2 mine, New Mexico’s El Segundo mine, and Wyoming’s Antelope and Black Thunder mines—produce more than 240 million tons of coal per year.

According to WildEarth Guardians’ analyses, the lifespans of these coal mines will be extended from three to 21 years because of the expansions approved between November 2013 and April 2015.

The environmental activists reviewed the applications for the mines’ expansions and identified similar problems in each—such as incomplete climate impact analyses and a lack of public involvement during the review process.

Carbon-Cost Accounting

Nichols said that there are two main ways regulators can strengthen reviews. First, they should be taking the cumulative climate impacts of the entire program into account. Second, he said, officials should use a government-sanctioned “social cost of carbon” tool to calculate the amount society will pay for the harm caused by each ton of carbon dioxide added to the atmosphere by the project.

Chris Holmes, a spokesman for the Department of the Interior, told InsideClimate News in an email that the agency does not comment on pending litigation.

Last July, WildEarth Guardians brought a successful lawsuit that halted the development of a federal coal lease in Colorado. According to Judge R. Brooke Jackson’s ruling, officials should have considered the global-warming costs associated with the project in addition to the supposed economic benefits during the review.

The energy companies had varying reactions to WildEarth Guardians’ latest lawsuit.

Cloud Peak Energy, the operator of Antelope mine, and Peabody Natural Resources Company, the operator of El Segundo mine, both defended their mines to InsideClimate News.

“Antelope mine’s federal coal leases and mining operations were thoroughly evaluated” in a process that included environmental evaluation and opportunities for public comment, said Rick Curtsinger from Cloud Peak Energy, owner of the subsidiary Antelope Coal LLC.

“The El Segundo mine plan was thoroughly vetted, and its approval was granted in accordance with all applicable laws,” said a Peabody spokesman.

The operators of Bowie No. 2 mine and Black Thunder mine both declined to comment.

WildEarth Guardians has filed similar lawsuits against the Interior Department relating to coal leases and coal mine expansions, with varying success. At least two cases relating to mines in Montana and New Mexico are ongoing.

The overarching goal of this case—and others—is to force regulators to be more transparent and thorough in their future management of coal leases.

“I think one of the things WildEarth Guardians is trying to do with this litigation … is to train the agencies that they have a duty to disclose climate impacts of things like coal mines,” said Zukoski.