Coastal cities like New York and San Francisco have already started legal battles with oil giants for knowingly fueling climate change. Now, landlocked communities in Colorado have filed their own suit against the oil companies Exxon Mobil and Suncor, both of which extract large amounts of oil and gas from the Colorado ground.

The lawsuit, filed by Boulder County, San Miguel County, and the City of Boulder, seeks compensation from oil companies "for the substantial role they played and continue to play in causing, contributing to and exacerbating climate change." These climate alterations, they argue, have brought increased heatwaves, droughts, and fire to the region. They believe Exxon and Suncor should pay for the damages.

Previously, lawsuits from coastal cities focused on sea level rise, not the other extreme manifestations of global warming. This is the first such climate lawsuit from an inland state, according to the local agencies which filed the complaint.

"A few pebbles are turning into a landslide," Kassie Siegel, director of the Climate Law Institute, a legal campaign to protect environments from climate change, said in an interview.

"It shows the tide is turning against fossil fuel producers," she said. "This is about fairness. It's completely unfair that taxpayers are being asked to pay for the costs of the damages done by oil companies."

The Colorado counties contend that oil companies have known about the long-term effects of greenhouse gas emissions for 50 years. They cite a report that Stanford Research Institute scientists presented to the American Petroleum Institute in 1968. The report warned that carbon dioxide emissions would warm the planet, melt ice caps, and "may be the cause of serious world-wide environmental challenges."

The report will likely serve as important evidence in the case, should the trial proceed and not be settled out of court or be derailed by a number of legal circumstances.

"I would expect that report and others like it would be key evidence in this case," said Siegel.

The suit also cites the 2017 National Climate Assessment, in which 13 federal departments and agencies found that high-temperature events and forest fires, among many other adverse effects, are expected to increase in frequency and intensity. U.S. government scientists stated bluntly: "This period is now the warmest in the history of modern civilization."

Some Colorado communities, who know these climatic shifts will adversely affect their business and agricultural sectors, are now working to decrease their dependency on fossil fuels. By 2030, the City of Boulder plans to generate all of its electricity from renewable energies, like solar.

"Communities in Colorado and across the country are already doing what they can to curb their carbon emissions and are spending millions of dollars to adapt to a wide array of harms caused by global warming," Ken Kimmell, president of the Union of Concerned Scientists, said in a statement. "Those costs will only multiply over the next few decades, and taxpayers shouldn’t be forced to foot the bill that the fossil fuel industry has knowingly run up over the last 40 years." The Union of Concerned Scientists is a nonprofit science advocacy organization that often speaks out against climate change deniers.

In the western United States, one obvious consequence of increased drought and heat are wildfires. Today's wildfires burn nearly year-round and burn significantly more land than wildfires did in the '70s, '80s, and '90s, posing an outsized harm to the forested state, which is consistently battling drought and low snow pack -- similar to California.

Both Exxon and Suncor sell oil in Colorado. Suncor has an especially prominent presence, as the company runs its operations out of Denver, a city currently facing drought. Suncor sends over 200 truckloads of Colorado crude oil to its refineries each day.

Last month, some of the nation's largest oil companies presented their understanding of climate science to a federal judge in San Francisco, in which they admitted humans were contributing to climate change, but side-stepped responsibility. These proceedings move incrementally, so it's not yet known if that hearing will advance to the next step, and then, potentially a trial.

But oil companies are now being hit with lawsuits from local governments on both coasts and the interior of the U.S.

"This shows you the list of governments that are being affected and that can take action is almost limitless," said Siegel. "The question is who will be next."