Ask Eartha: Water and climate change
I know that climate change will impact ski seasons, but I’m a kayaker, too. How will climate change affect our local rivers?
— Tom, Frisco
As summer draws to a close and we start packing our aquatic toys for the season, it’s an excellent time to reflect on how important our waterways are. Whether you’re a kayaker, rafter, SUPer, fisher, Lake Dillon beachgoer or just a human, water is essential to our well-being. Unfortunately, climate change poses a serious threat to our water availability.
The mighty Colorado
One of the West’s mightiest rivers, the Colorado, is right in Summit County’s backyard. Over the course of its 1,450 miles, its waters serve more than 40 million people and irrigate 15% of U.S. agricultural products. Vegetables in wintertime? Lush golf courses in the desert? Thank the Colorado River.
Since 2000, the Colorado has been in an extended drought. In fact, data from tree rings indicate that this is the most extreme drought our region has experienced in the past 1,250 years. On average, annual flows are down more than 16%. Water levels in the nation’s two largest reservoirs, Mead and Powell, are at all-time lows. Summer 2018 was the warmest and driest on record in the Colorado River Basin going back to 1895. Why? Scientists have linked the decline in flows to higher temperatures from our rapidly changing climate.
The ripple effect
Warmer temperatures affect water supply in a few ways. First, as temperatures increase, more wintertime precipitation falls as rain instead of snow. In the Upper Colorado watershed (where we live), 73% of winter precipitation falls as snow. If we do nothing to fight climate change, only 43% of winter precipitation would fall as snow by 2065.
A higher rain-to-snow ratio is problematic and not only for ski season. Snowpack serves as a frozen reservoir. It’s our water storage for summer. As the snow gradually melts, we receive a relatively continuous supply of water in streams and rivers. Think about how full Lake Dillon gets every spring as the snow starts to melt. But unlike snow, rain runs off instantaneously, leading to decreased summertime flows. In 2018, raft companies across the Colorado River Basin had to cut their seasons short because flows in the river were too low.
Higher temperatures also affect evaporation. How? Warm air is thirsty; it holds more moisture than cooler air. As temperatures increase, more water vapor will be absorbed from the soil, plants (including crops) and waterways. Again, this has multiple consequences. With respect to agriculture, drier soil and crops will require increased irrigation, pulling more water from rivers. But lakes, streams and rivers will have less water available simply because of increased evaporation. One study found that for every 1 degree Fahrenheit increase in temperature, the flow of the Colorado River declines by 4%. And keep in mind, declined flow also leads to increases in water temperature, putting stress on fish and other aquatic life, not to mention the wildlife that feeds on the fish.
Average temperatures across the state already have increased 2 degrees Fahrenheit in the past 30 years. Depending on what the global community does to limit future emissions, we could see an additional 6.5 degrees warming here in Colorado by 2050. That would mean the flow of the Colorado River could decline by more 25%. That scenario does not bode well for future river floats.
If climate change weren’t bad enough, the Colorado River is tapped. The Colorado River Compact, created in 1922, allocated the river’s water among the seven basin states and Mexico. But the compact promises more water than actually exists. An increasing population requires even more water to survive, but there simply isn’t enough to go around.
Frankly, the river is at risk. If you’re interested in learning more about the future of the Colorado River, join the High Country Conservation Center from 6-7:30 p.m. Wednesday, Sept. 18, at the Frisco Adventure Park Day Lodge for a talk by Brad Udall, the senior water and climate research scientist at the Colorado Water Institute. Udall will discuss the past, present and future of the Colorado River in a changing climate. The talk is free to attend, and light refreshments will be provided.
Ask Eartha Steward is written by the staff at the High Country Conservation Center, a nonprofit organization dedicated to waste reduction and resource conservation. Submit questions to Eartha at email@example.com.
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