What does a warmer future mean for Utah’s rivers?
Rising temperatures mean we need to prepare ourselves for a future with less water in Utah’s rivers.
Regardless of what you believe about our climate, it is undeniable that Utah’s temperatures have risen dramatically over the last 30+ years. This temperature increase creates a cascade of impacts to Utah’s watersheds and will have major economic impacts on every Utah resident. We are at a crossroads—we can continue to ignore the effects of the changing climate or we can adapt to this new climate reality.
Utah—unprepared and unaware
Utah is woefully unprepared for the effects that warmer temperatures will have on virtually every part of the state’s economy—from healthcare to recreation. In fact, a study by NRDC ranked Utah as being one of the 7 least-prepared states for the challenges of the 21st Century. We can mitigate the damage, but only if we respond appropriately.
More Rain, Less Snow
Cities and towns across the American West owe much of their existence to snow—and Utah’s cities are no different: Over 80% of the Wasatch Front’s water comes from snowmelt. Increasing temperatures will result in more rain and less snow. This, in turn, threatens our snowpack, which will have massive consequences on our ecosystems and economy.
Wetter isn’t always better.
Climate models indicate there will be a 10-15% increase in precipitation levels with different projections between Southern and Northern Utah, but rising temperatures mean this will occur more frequently as rain—leading to less snow accumulation and an earlier snowmelt. Because the snowpack is instrumental in holding water and preventing loss through runoff, less snow and earlier melts could lead to droughts and shortages.
The water formerly known as the “Greatest Snow on Earth.”
An analysis of snowpack between 1979 and 2008 in both the Ben Lomond watershed and in the Oquirrh Mountains made some startling estimations. One study estimated there would be an 8 – 10% decrease in snow with each 1°C in warming of the air mass above the surface (the troposphere).
Over the past 100 years, the Earth’s average temperature has increased 1.3°F. Utah’s distance from the ocean’s cooling effects has lead to more dramatic temperature increases over the same period—about 2.7°F.
By 2050 it has been estimated temperatures in Utah will be ~3°F higher in winter and ~3.6°F higher in the summer compared to current temperatures. By the year 2100, average air temperatures in Utah may increase by ~6°F in winter and by ~8°F in summer above today’s temperatures. The effects of such a drastic temperature increase will be catastrophic—especially if we continue to ignore the issue.
What’s the big deal about a few degrees?
A few degrees warmer might seem like a small change, but it could have huge repercussions—particularly by increasing the frequency and severity of extreme weather events like droughts, floods and heat waves. As you can see in the model below, an increase of just 3°F in the average air temperature skyrockets the odds of having a drought by 2,500% (or one drought for every three years). Apply this same concept to floods, heat waves and wildfires, and it becomes clear that we need to think carefully about how to prepare for more risk.
The coming megadrought
Today, the Colorado River Basin provides water to over 30 million people, and over 80% of that water comes from snowmelt in headwater states, including Utah. This means Utah’s snowpack is critical not just to Utahns, but also to Westerners from far outside Utah’s borders. Unfortunately, increased air temperatures are expected to lower Colorado River stream-flow by 9-30% in coming decades according to a Bureau of Reclamation study.
This decrease in available water means the American Southwest will likely see a long-term drying period with lower precipitation levels—something that historically occurred only once every hundred years and is now predicted to become more frequent. Coined the “megadrought,” it will be particularly difficult for Southern Utah, where streams already are under great duress during summer months.
Southern Utah’s low elevation watersheds in particular will feel the megadrought because of the reduced volume of snowpack expected at lower elevations. Watersheds like the Beaver Dam Wash, the Virgin River and the Santa Clara face greater water deficits for native aquatic ecosystems as existing water diversions are magnified.
These flow reductions are bad news for tens of millions of residents in the lower Basin—especially those wanting to see the Colorado River Delta restored. If we are ever to restore this estuary, new diversions must be carefully scrutinized.
It’s time to act
Utah is already the second most arid state in the nation, and as temperatures continue to increase we can expect less snow at the end of each winter. That makes it hard to imagine why Utah water suppliers are years behind the rest of the West in determining the impacts of the decreasing snowpack. These agencies need to estimate how much less water they will receive in coming years as a function of these losses, and make up time to develop a better plan for mitigating the damage caused by climate change.
Learn More About How Utah Can Start Adapting for a Warmer Future by Reading our Crossroads Utah Report