As melting snow dripped from the roof of the Vail Pass Rest Center on Wednesday, March 18, Kevin Walsh and Sam Dees pulled off their sopping wet boots and felt the sun-warmed cement under their bare feet.
The two visitors from St. Louis had stopped at the top of the 10,662-foot mountain pass along Interstate 70 around 10 a.m. that morning and decided, with little planning, to hike up into the national forest.
With no snow gear other than hiking boots, the two ascended into the mountains wearing just T-shirts and thermals. While the snow mostly held their weight on the way up, they said it quickly became unsupportive as temperatures climbed well-above freezing.
"Once the sun was at its peak, it started melting real fast. You could see the snow glistening everywhere," Dees said. "This is supposed to be deep winter. Everything is supposed to be frozen."
On the way down, Walsh and Dees found themselves sinking into the wet snow, soaking their boots, socks and legs. By the time the two friends made it back to the parking lot a little after 2:30 p.m., temperatures had soared to roughly 54 degrees.
"That just proved to me that global warming is real for sure," Walsh said with a nervous laugh.
"People should stop treating it as a joke," Dees added.
Amid an already record-hot winter and some of the worst snowpack conditions in the state's history, Colorado -- and most of the West -- is experiencing a winter heatwave that climate scientists say would be hard to imagine without the influences of climate change.
In Colorado's mountains, temperatures have soared 20 to 30 degrees above average for this time of year for several days in a row and are expected to remain high through the weekend, according to the National Weather Service. Nearly the entire Western United States is cooking under the same heat dome.
"We've never seen such a widespread exceptional climate fingerprint, starting from 1970 to now," said Kaitlyn Trudeau, a senior research associate with Climate Central. "So this is just a really exceptional event, and it would be very, very, very unlikely for something like this to happen without human-caused climate change."
Colorado Assistant State Climatologist Peter Goble said the temperatures the state has seen this week are "unprecedented for March."
Colorado has already experienced a record-warm winter as a persistent ridge of high pressure has hung over the southwestern U.S., deflecting away cold air and precipitation from the north, Goble said. He said this week's heatwave is being driven by that same high pressure system, except the high pressure ridge is even more intense and is driving even higher temperatures.
"The thickness of the high pressure ridge is just conducive to much warmer temperatures than even what we would typically see in March," Goble said. "It looks a lot less like winter and a lot more like a summer pattern."
In Dillon, one weather station with a record that dates back to 1910 recorded the warmest-ever temperature for March on Wednesday, when temperatures reached 65 degrees, smashing the previous record of 63 degrees set in 2012. Thursday was even hotter, with temperatures in Dillon hitting 67 degrees, according to the National Weather Service data.
A Steamboat Springs weather station, also with over 100 years of data, smashed records for the warmest March temperature as well. On Wednesday, temperatures hit 72 degrees. Then, on Thursday, they hit 76 degrees, according to data. Both days set new records, breaking the previous record of 70 degrees set in 2017 and 2004.
While natural variability is playing a role in the record temperatures the West is experiencing this week, Goble said climate change almost certainly helped to push temperatures even higher than they would have been without human-caused pollution. This year's record temperatures continue a long-term pattern of more recent winters being warmer than those prior to the turn of the century, he said.
Statewide, annual average temperatures have warmed by about 2.3 degrees Fahrenheit between 1980 and 2022, due to the amount of heat-trapping gasses humans have released into the atmosphere, according to the Climate Change in Colorado report.
"We should be prepared for temperatures to be warmer. The average winter probably won't be as warm as this winter for quite some time," Goble said. "But the above-average winters may be as warm as this winter, and we should be prepared for the droughts when they do happen to be more frequent and more intense."
With the way conditions aligned this year, Goble said natural variability played a big role but climate change also likely contributed to the warmer weather.
"Our winters -- and all seasons for that matter -- are getting warmer. Climate change does at least raise the probability of something like this," he said. "But I can't sit here and say that this is going to be the new normal. I think even 20, 30, 40 years down the road, we're going to remember this winter and that it was weird."
While climate scientists can't say whether any particular weather event was caused by climate change, Trudeau said that scientists can calculate how much more likely certain temperatures are made because of the greenhouse gasses humans have released through burning fossil fuels.
Climate Central's daily attribution tool, the Climate Shift Index, applies the latest peer-reviewed methodology to map the influence of climate change on temperatures across the globe every day.
"The only thing we're taking out of the climate models that we're comparing against are the human carbon-emissions since the Industrial Revolution," Trudeau said. "The natural variability and stuff is still baked in. So, when we compare the two, what we're really comparing is the influence of human-caused climate change."
On an overlay of the U.S. or world map, the tool outputs a level between 1 and 5 over geographic regions. Level 1 indicates very little human climate influence, while Level 5 is associated with a strong climate influence and means the hot conditions experienced in that region were made at least five times more likely due to climate change.
Across Colorado, and almost the entire West, the Climate Shift Index was maxed out at Level 5 from Tuesday through Saturday this week. Trudeau said that indicates a very strong climate signal that likely helped push temperatures even higher than they would have been without the influence of heat-trapping gasses released by fossil fuel burning.
"In fact, I think it's very unlikely you'd experience anything like we're experiencing now, if there wasn't human-caused climate change," she said. "All that extra carbon we've added to the atmosphere is really increasing the heat. I think this is a scary preview of what is to come. This is what unchecked warming looks like. We have these really intense, crazy conditions that people have never really seen before."
While addressing climate change can sometimes feel hopeless, Colorado climate advocates say both the cause of the problem and the solutions are known -- and there are more individuals and groups who are ready to take action than people think.
Aspen One Director of Sustainability Hannah Berman said that climate change is a "systematic problem" that will require a societal push to combat. For Colorado, and a business like Aspen One, which operates the four Aspen ski resorts and several hotels, there are clear consequences of not taking action, she said.
"We see climate change as an existential threat to our business operations," Berman said. "We are inherently dependent on winter, but Aspen is a place that has lost a month of winter since 1970. That's 31 days that no longer get below freezing that used to."
One analysis published this winter determined that climate change is already costing Colorado -- and could cost the state up to $37 billion by 2050 due to impacts like shorter ski seasons, longer wildfire seasons and damage to infrastructure.
While businesses like Aspen One are taking steps to reduce their greenhouse gas emissions, Berman said collective action at a societal level is what will make real change, so the company also advocates for climate policies.
"That's why we leverage our influence and our voice and our brand recognition to push forward electrification of buildings, of vehicle fleets -- because it's going to take everyone," she said. "Not just one company. Not just one industry. Not just one town."
As the climate action director for the Summit County-based High Country Conservation Center, Jess Hoover helps local residents learn more about the steps they can take to reduce their impact on the climate, from installing a heat pump or solar panels to recycling and composting.
Hoover noted that Colorado has a climate action plan and has set goals such as requiring Xcel energy to produce 80% of its energy from renewable sources by 2030, which is only four years away. She said it will take a concerted effort from the public to keep the state -- and the world -- on track with climate goals but the solutions are clear: Cut emissions.
In Colorado, Hoover noted that many communities have done studies to determine where the most greenhouse gas emissions are coming from. In Summit County, she said one such assessment determined that most of the county's greenhouse gas emissions come from energy-use in buildings..
"It's a huge advantage to know that, because we can focus on decreasing those emissions," she said.
Anyone who is concerned about climate change should get involved in local or state politics to advocate for proactive climate policies, like a bill currently working its way through the state legislature that would allow for balcony-mounted solar panels, Hoover said. With upcoming elections, both Hoover and Berman noted it is important for people who are concerned about climate change to vote for candidates who support proactive climate policies.
If nothing else, Hoover said it is important to talk about climate change with friends and family. While there is sometimes a perception that others don't care about climate change, she said that's not true.
One 2024 poll found that 72% of U.S. adults believe climate change is happening, 63% are at least somewhat worried about it and 59% believe it is caused by human-activities.
"Talk about it. Normalize it," Hoover said. "A majority of Americans agree that this is real and that it's happening and that it's human-caused and we should do something about it."
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