A new report from the Colorado Climate Center at Colorado State University shows statewide annual average temperatures warmed by 2.3 degrees Fahrenheit in the last four decades. The season with the greatest warming is fall.
Assistant State Climatologist Becky Bolinger, one of the co-authors of the report, says the researchers compared rising temperatures in Colorado with warming trends that are happening globally.
Becky Bolinger: So we do have a comparison early in the report that kind of looks at how temperature changes in Colorado compared to the United States as a whole and then compared to the globe.
The thing about the globe is you're going to see changes that aren't quite as big because the globe is majority ocean, and ocean temperatures regulate that change and keep that change from happening faster. So since we're a state, we're landlocked, we're far away from moisture sources, it's easier to get bigger swings in temperatures and also to have more significant warming than what you would see globally.
So while everywhere in the globe is really experiencing warming, and will continue to experience warming, the magnitudes are going to vary depending on where you look.
Sam Fuqua: And one of the obvious places everybody can look is our waterways for the impact of that, as we all see lower rivers, we see lower lakes, lower reservoirs.
Becky Bolinger: Yeah, so in chapter three of the report we focus on Colorado's water. It's a really important resource for us, and many states that are downstream from us since we have so many major rivers that actually start in our mountains.
And so most of that river runoff starts at snowpack. So we look at snowpack and how that might change with climate change. And you know, there's uncertainty with what the future of precipitation is going to look like, and with that comes some uncertainty with what our future of snowpack looks like, but those warming temperatures are going to kind of reduce the efficiency of that system to make snowpack into a streamflow runoff and available water supply for us.
And so we've already seen reductions in stream flow, and that is something that is expected to continue. We will see more reductions because we are losing more of our water to the atmosphere, and less of it is staying on our surface for us to use.
Sam Fuqua: Your models predict a 5 to 30 percent reduction in stream flows and snow melt. That's a really broad range. Why is it so difficult to predict with more certainty the precipitation trends?
Becky Bolinger: Right. Part of the reason that it's more difficult is because most of our confidence is in what's happening with temperature, which is about the easiest indicator to predict in near term and in longer term.
But once you get into precipitation, there's a lot of different variables that can control how you see those changes and some of those variables are internal, they're not regulated by climate change.
So our state is a great example. We have a lot of variability. We have very wet years, very dry years, and we have these rapid swings between those years, and so small changes, small trends are difficult to detect because of that.
What we do know is that even if it's wetter, it has to be significantly wetter to make up the losses that we would have from warmer temperatures, and so it's more likely that those reductions are going to continue.
It's just the smaller reductions in streamflow and snowpack would happen with wetter precipitation, a little bit wetter precipitation, and only in times when it's significantly wetter would we see an increase in streamflow or snowpack, which is unlikely, I think, at this point.
Sam Fuqua: So we're coming off a wetter year, 2023, but if I'm hearing you correctly, that is perhaps an anomaly.
Becky Bolinger: So we know that we will have those wetter years, 2023 is an example, 2019 is another example. Unfortunately, we're getting more dry years in between those, and so it's harder to make up the deficits from the more frequent drier years with the wetter years that are kind of in between.
And so overall, it seems that will lead to us being overall drier, even when we have those wetter times.
Sam Fuqua: And finally, I'd ask you to comment on the impact of drier, hotter conditions on extreme events. So I'm talking about heat waves and their impact on public health and animals and ecosystems, wildfires, these extreme events that we seem to be seeing more of.
Becky Bolinger: Yeah. So in chapter four we do a focus on the hazards and extremes that Coloradans are vulnerable to and that we've experienced in the last 22 years particularly.
And those have been an increase in heat waves. The frequency of heatwaves, however they would be defined, is increasing. And the severity of those heat waves, they are getting hotter.
And so that is something that we're going to have to deal with as we move into a future climate that will continue that trend. And it's going to continue later into the season. And this is something that we've been experiencing, particularly in the past few years where we're still having summer-like temperatures extending into September and October. And so these are things that are going to have to be considered.
Another major one, as you mentioned, is wildfire. We have the evidence that climate change has contributed in portion to the increasing number of wildfires we have and the increasing size of those fires. So we're seeing more fires and we're seeing larger fires. And the big player in that is that dryer air, which really alters that fire behavior, and also lengthening the window between snowpack seasons just provides more opportunity for wildfires to start.
And so those are a couple of the contributing factors that are going to be something that we're going to have to think about and prepare for in our future climate, and basically our climate of today.
One more I would say is drought. We are experiencing an increased frequency of drought. And more severe droughts because of hotter temperatures. This is having an impact on our recreation, it's having an impact on our water supply, it’s having an impact on agriculture in our state. And so, that is another challenge that we have to deal with.
Sam Fuqua: As a scientist, when you see data like this and these trends that just personally are alarming to me, how do you react?
Becky Bolinger: So it can definitely be disconcerting, especially as individuals regardless of your profession, when you're experiencing some of these extremes, right? I could see the flames from Cameron Peak Fire from my own neighborhood.
And it's scary, and the fact that these things can happen into the future still is also scary. And one of the things that I like about this report is that it provides the information for better planning. And we have a state that is really good at that sort of thing and in the planning process.
And so there's two sides to climate change. There's the mitigating climate change, and that's where we're talking about, reducing greenhouse gas emissions and trying to reduce the amount of warming that we are experiencing and will experience.
And then there's also adaptation to the climate change that's already occurring and will continue to occur, and that's where I like to think that we have a little bit more control, especially locally, over decisions, plans to make sure that we are prepared for events like this.
Sam Fuqua: And that's the state's assistant climatologist, Becky Bolinger, co-author of the new Colorado Climate Report. You can find the report online at climatechange.colostate.edu.
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This story was shared via Rocky Mountain Community Radio, a network of public media stations in Colorado, Wyoming, Utah and New Mexico including Aspen Public Radio. It was shared via Rocky Mountain Community Radio, a network of public media stations in Colorado, Wyoming, Utah and New Mexico including Aspen Public Radio.
