Water wonks, state and tribal officials, attorneys and irrigation district representatives hit the floor at Bally's Las Vegas Hotel last week. Not to shake loose the slots. But to gamble on the future of the Colorado River.

During the annual meeting of the Colorado River Water Users Association (CRWUA), stakeholders from the seven US states that share the river's water met to talk about everything from interagency cooperation to cloud seeding, forecasting to tribal water rights.

But even as the impacts of the Earth's warming are increasingly clear, there's still a political and practical disconnect between the cause of climate change—the burning of fossil fuels—and the challenges warming poses to water supplies in the western United States.

That decoupling was hammered home by US Department of the Interior Secretary David Bernhardt, who spoke at the CRWUA meeting. During his keynote speech, Bernhardt avoided mentioning climate change.

When pressed by reporters afterwards, he said he "certainly believe[s] the climate is changing." But he cautioned that forecasting is speculative.

And he praised the role energy development plays in states like New Mexico.

"The president was very clear when he ran for office on his position on energy; he's for an all-of-the-above approach," Bernhardt said. "In New Mexico last year, we sent $1.7 billion from federal lands to the state of New Mexico that went to schools and other things. So, when people tell me they want to stop oil and gas development on federal lands, I say 'Call the governor of New Mexico.'"

Gov Michelle Lujan Grisham's office could not answer SFR's questions by deadline about Bernhardt's claims related to revenues from drilling on federal land in New Mexico and balancing the disconnect between the state's energy policies—which have spiked revenues—and emissions from that industry, which exacerbate the state's water challenges.

The governor's spokeswoman also could not provide a response to Bernhardt's statements before deadline.

Today, the Colorado River supplies water to an estimated 40 million people—from the mountains of Wyoming and Colorado to booming southern California cities like San Diego and Los Angeles. Due to withdrawals from the river, which also supplies enormous irrigation districts in southern California and Arizona, since the 1950s, the river has consistently failed to reach its own delta at the Gulf of California.

But it isn't just the demands placed upon the river. Its flows are also dropping due to climate change.

In 2017, a peer-reviewed study showed that warming was already causing flows on the Colorado River to decline. Between 2000 and 2014, flows averaged 19% below the 1906-1999 average, and scientists found that one-third of those losses were due to higher temperatures, rather than changes in precipitation. They also wrote that if warming continues, the Colorado River's flows will drop even more—20 to 35% by 2050, and 30 to 55% by 2100.

A follow-up study in 2018 showed that even though annual precipitation in the Colorado River Basin increased slightly between 1916 and 2014, flows declined by 16.5 % during that same time period—due in large part to "unprecedented basin-wide warming."

"Climate change is water change," says Bradley Udall, one of the co-authors of both those studies. Udall is a senior water and climate research scientist at the Colorado Water Institute at Colorado State University.

In arid landscapes like the US Southwest, warming affects river flows, snowpack, soil moisture and even the amount of water crops and forests need to survive.

"In our case, [climate change] means these longer, hotter droughts that threaten the Rio Grande and the Colorado River system in ways that are unprecedented," Udall tells SFR.

"If you're going to reduce the risk of water shortages for humans and nature, you've got to solve the climate change problem."

And, he says, solving the climate change problem means stopping fossil fuel production: "You can't solve climate change if you're going to continue to pursue fossil fuel production willy-nilly."

And yet, drilling is booming across the world, including in New Mexico. And that development has consequences.

Earlier this year, the World Meteorological Organization showed that carbon emissions have continued to increase. According to a story in the BBC, "Using data from monitoring stations in the Arctic and all over the world, researchers say that in 2018 concentrations of CO2 reached 407.8 parts per million (ppm), up from 405.5ppm a year previously. This increase was above the average for the last 10 years and is 147% of the "pre-industrial" level in 1750." Not only that, but methane emissions continue to rise, as well—and is now at 259 % what it was before the Industrial Revolution.

Meanwhile, global temperatures continue to ruse. The latest numbers from the National Oceanic and Atmospheric Administration show that the three-month season of September through November 2019 ranked second-warmest on record for the globe—with a global temperature of 1.69°F above average. Already, New Mexico's average annual temperature has increased by 2°F—just since the 1970s.

Continued warming will have continued impacts across the US Southwest. And even after last winter's robust snowpack, the basin's reservoirs, system-wide, sit at just over half-full. The two largest reservoirs, Lake Powell and Lake Mead, are 52 % and 40 % full, respectively. A second year of good snowpack, Udall estimates, would put the system at perhaps 60 % full.

Of course, there are never guarantees of a good year.

Udall says decision-makers shouldn't become complacent. Nor should people throw up their hands.

"Climate change gives us an opportunity to do things in new and interesting and innovative ways," he says. "It provides us the opportunity to get out of the box of 20th century ways of doing things—and a 21st century way might actually bring terrific benefits, like cleaner air, cleaner water and jobs to people in [new] industries."

At last year's CRWUA meeting, the seven US states that draw water from the Colorado River were racing to come up with what are called "drought contingency plans." These plans came under orders from then-Interior Secretary Sally Jewell, who in 2013 told states they needed to find better ways to share declining water supplies than outlined in the 2007 interim guidelines under which they were operating.

By the spring of 2019, states at the top of the basin—Wyoming, Colorado, Utah and New Mexico—and states in the lower basin—Nevada, Arizona and California—had agreed to drought contingency plans, and in April 2019, Congress and President Trump approved those. Those plans, which focus on things like reducing water demands, keeping reservoirs full enough to operate, and considering weather modification projects like cloud seeding, will be in place through 2026.

Speaking at the tail end of the meeting, Bernhardt, praised the states for their work in the Colorado Basin. He also praised his boss—President Donald Trump—for his leadership, including on western water.

Asked to rectify that with the president's statements about climate change as a "hoax" and his attacks on climate science, Bernhardt reiterated that Trump has been an "exceptional leader on western water issues."

"I think it's very hard to go back and find presidents who have given clear direction in memos to the secretaries, [that] say 'Get on with it. Solve these situations,'" he said, referring to Trump's 2018 presidential memorandum on reliable water supplies in the western US. In that memo, the White House directed federal agencies, including Interior, to "work together to minimize unnecessary regulatory burdens and foster more efficient decision-making so that water projects are better able to meet the demands of their authorized purposes."

Bernhardt also directed the US Bureau of Reclamation to launch its review of the 2007 interim guidelines at the beginning of 2020.