In Boulder, Colorado, climate change means extreme weather and wildfires. It means worrying about water security for people and farms, and about heat waves and mosquito-borne diseases. These aren't just future risks—they're problems the city and its surrounding county are facing now.

On Tuesday, the city and Boulder County joined San Miguel County, home to the ski slopes of Telluride, in suing two fossil fuel companies—ExxonMobil and Suncor—over the costs of dealing with climate change.

Their lawsuit is the latest in a string of legal actions by communities that are attempting to hold fossil fuel companies accountable for the problems climate change creates. Until now, the plaintiffs had been coastal cities and counties worried primarily about sea level rise.

The new case takes climate litigation to the middle of the country, where the risks take on new shapes and high costs.

The Colorado communities are already seeing climate-related damage to property, health and safety, and "the damage will only multiply as climate change worsens," the lawsuit says.

It points to the dwindling snowpack, which is critical for the state's agriculture, water supply and $5 billion ski industry. (This month, the snowpack in the mountains of southern Colorado was less than 50 percent of normal.) It also raises concerns about the loss of water flow into the Colorado River, and about extreme summer heat, wildfires and droughts. (San Miguel County, like much of the Four Corners region, is facing extreme drought conditions.)

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The Colorado plaintiffs, like the cities and counties suing oil companies in California, accuse Exxon and the Canadian oil sands company Suncor of creating a public nuisance through the burning of fossil fuels that is costing them money and putting their residents and property at risk.

They say the fossil fuel companies "intentionally engaged in conduct that has caused and contributed to climate change, thus causing flood waters, fire, hail, rain, snow, wind and invasive species to enter plaintiffs' property."

And they also cite the Colorado Consumer Protection Act, claiming the companies engaged in "deceptive trade practices"—an allegation similar to the Massachusetts attorney general's investigation currently underway into Exxon.

Taxpayers Can't Afford What's Needed

The lawsuit makes clear that the plaintiffs aren't asking for the court to stop fossil fuel production in Colorado, or elsewhere, and they aren't asking for emissions regulations. Instead they want compensation for a wide range of past and future damages related to climate change, ranging from the cost of fighting wildfires to flood control measures, health care expenses and the loss of land value.

Suncor and Exxon "knowingly and substantially contributed to the climate crisis by producing, promoting and selling a substantial portion of the fossil fuels that are causing and exacerbating climate change, while concealing and misrepresenting the dangers associated with their intended use," the complaint says.

Taxpayers can't pay the full costs of what's needed, and they shouldn't have to, says the lawsuit, which has the backing of the libertarian think tank Niskanen Center.

Asked about the lawsuit, Exxon spokesman Scott Silvestri told Bloomberg: "Reducing greenhouse gas emissions is a global issue and requires global participation and actions. Lawsuits like this—filed by trial attorneys against an industry that provides products we all rely upon to power the economy and enable our domestic life—simply do not do that."

Exxon Knew of Colorado Risks in 1970s

The 106-page complaint sketches a timeline of what Exxon knew about the risks fossil fuels pose to the climate, starting in the 1970s.

It accuses of Exxon and Suncor of developing and selling dirtier fuel sources, notably Canadian tar sands oil refined in Colorado, "long after they became aware of the dangers of climate change."

Among other things, it cites a 1979 internal Exxon document that discusses academic research around possible changes in the climate once atmospheric concentrations of carbon dioxide reach about 500 parts per million. The document mentions the flow of the Colorado River diminishing, water shortages in the Southwest becoming more acute, and less winter snowpack in the Rockies. (The CO2 concentration today is about 410 ppm, up from 317 ppm 60 years ago.)

The lawsuit alleges that the companies "acted to prevent and forestall changes in energy use and supply, which they knew were needed. ... By hiding what they knew about, and affirmatively misrepresenting the dangers of unabated fossil fuel use, the Defendants protected fossil fuel demand, and obstructed the changes needed to prevent or at least minimize the impacts of climate change."

Some of the Climate Costs Communities Face

The complaint also provides a snapshot of some of the costs the city and counties are already facing. For example:

An extreme rainstorm that brought nearly a year's worth of rain over eight days damaged 150 miles of roads and 30 bridges in Boulder County a few years ago, costing well over $100 million.



San Miguel County is seeing a trend of larger and more frequent wildfires, and the burn area is projected to increase 40 percent by 2050, the lawsuit says. Wildfire response there can cost hundreds of thousands of dollars per day.



The city of Boulder, which didn't have a mosquito control program before 2002, had to budget roughly $250,000 for mosquito management this year out of concern about the spread of vector-borne diseases like West Nile Virus as temperatures warm.



In both regions, crops are at risk from drought and changing precipitation. The lawsuit states that more of the state's precipitation falls as rain rather than snow now, reducing the snowpack, which is the source of 70 percent of the state's surface water. Many communities and farms rely on the snowpack for water supplies and irrigation.



And then there's the heat. Buildings across both regions were built for the historical climate, which didn't require air conditioning, yet Colorado has seen average temperatures rise 2.5 degrees Fahrenheit over the past 50 years.

"In an ideal world, we'd put an economy-wide market price on carbon energy to create funding to pay for the necessary costs of adapting to climate change," Jerry Taylor and David Bookbinder of the Niskanen Center wrote about the lawsuit. "But until that day comes, holding manufacturers responsible for the damages they impose on others is the next best thing. To do otherwise is to green-light violence to property rights and individual liberty in the name of corporate profit, and that is something that conservatives and libertarians should never do."