Colorado’s warming climate means scarcer water supplies, 10 times as many summer heat waves and more intense wildfire seasons, according to a new comprehensive study of how climate change will affect the state.
The state’s annual average temperatures increased by 2.3 degrees Fahrenheit between 1980 and 2022, according to the third edition of the Climate Change in Colorado report, set to be released Monday by Colorado State University. Although that amount of warming may seem small, it’s enough to significantly impact agriculture, severe weather and water supplies.
But there’s good news, too.
Researchers 10 years ago — the last time a similar report was completed — expected worse. The predictions in the 2014 edition were based on a scenario in which Coloradans and the world did not do anything differently to mitigate climate change.
People have made changes, though, and the data collected over the last decade are not as dire as predicted, said Becky Bolinger, Colorado’s assistant state climatologist and one of the 2024 report’s authors.
“It’s our small silver lining,” she said.
Colorado’s warming trends are consistent with the rest of the globe, which has warmed substantially since the 1980s, the report states. That warming has been driven by an increase in greenhouse gases such as carbon dioxide and methane, which trap heat in the lower atmosphere.
In 2022, the average level of carbon dioxide in the atmosphere was higher than at any other time in the last 2 million years, according to the report. Its findings are in line with those of a massive federal climate change assessment released in November.
The results can feel like doom and gloom, Bolinger said. But the findings are an important part of the puzzle for society to adapt to a new reality.
“This type of report, it’s just giving the science,” Bolinger said. “But this science is being used by state entities, by local governments to take this information and integrate it into their planning. This is arming us with the information we need to better prepare, so we’re not the ostrich sticking our heads in the sand and pretending this isn’t happening.”
Here are some of the ways a warming climate will affect Colorado, according to the new report.
Warming temperatures
By 2050, scientists expect the state’s average temperature will reach up to 5.5 degrees hotter than the baseline average computed between 1971 and 2000. And by then, the average year will be as hot as the hottest years Colorado experienced through 2022.
And it will only get hotter from there, the report says.
Of the seasons, fall has warmed the most already, particularly in September and November, Bolinger said. Summer is stretching.
“People are feeling the warmer falls,” Bolinger said. “Those hot summer temperatures are something we’re going to have to deal with.”
Decreasing water supplies
The future of precipitation in the state is less certain, Bolinger said.
While Colorado has experienced continuous dry conditions over the last 20 years, climate models show precipitation could either increase or decrease over the coming decades.
However, the certainty of a warming climate means that the benefits of any increased moisture will be minimized, according to the report. Drier air and soils will quickly suck away moisture, reducing streamflows and making droughts more frequent and more severe. The amount of water in Colorado’s snowpack is expected to decrease across the state because of warming, as evaporation increases — regardless of the potential for increased precipitation.
“It is uncertain how much Colorado’s climate will warm and it is not precisely known how sensitive the streamflow in Colorado’s river basins is to each increment of warming,” the report states. “However, the science is clear: further warming alone will push the water cycle towards reductions in streamflow and water supply.”
Drier soils — resulting in more heat
Warmer temperatures likely will mean drier soils, which will reduce crop yields and stress native vegetation. Drier soils also result in more dust on the mountain snowpack, which speeds melting.
Dry soils also contribute to warming, the report says, creating a feedback loop. The sun’s energy causes water to evaporate from soil and to transpire through plants, but with less moisture, more of that energy instead will heat the earth’s surface.
Wildfires and extreme weather
Scientists project that heat waves will happen 10 times as frequently in Colorado by 2050, according to the report. In most regions of Colorado, the median number of heat waves will increase from one per year to about 10 per year by 2060.
“Heat waves in the summer are something that people feel and that a lot of populations are vulnerable to,” Bolinger said.
One study cited in the report found that the severity of heat waves that contributed to the 1930s Dust Bowl now have a probability of occurring in one out of every 40 years. In the 1930s, the probability was one in 100 years.
Wildfires also will grow larger and more intense as Colorado becomes drier and warmer.
Eight wildfires larger than 10,000 acres burned in Colorado between 1984 and 1999. In the 23 years since, there have been 60 wildfires of at least that size. The wildfire season will lengthen and more fires will occur in the fall, winter and spring, the report says.
Factors outside of climate, such as forest management, also affect fires. But several studies cited in the report found that climate change is contributing significantly to the increase in fire activity in the western United States.
“In short, studies consistently project a continuation of the recent increasing statewide trends in wildfire, given the near-certain continuation of the recent warming trend,” the report says.
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