Claim: How climate change dries up mountain streams

Modeling. Not reality.

The media release is below.


How climate change dries up mountain streams

The western United States relies on mountain snow for its water supply. Water stored as snow in the mountains during winter replenishes groundwater and drives river runoff in spring, filling reservoirs for use later in summer. But how could a warming globe and a changing climate interrupt this process?

In a new study in Environmental Research Letters, a team of hydrologists that includes University of Utah professor Paul Brooks answers that question by simulating isolated climate change effects on Rocky Mountain stream systems, varying the type of precipitation (rain vs. snow) and the amount of energy (temperature) in the system. The answer, they found, depends less on how water enters the stream watershed, and more on how it leaves.

Balancing the water budget

Hydrologists often construct water budgets to account for all the ways water enters and leaves a system. In the case of a mountain stream, water enters as precipitation but only a portion of this water leaves as streamflow. Much of this melt water enters soils. Here it can be used by plants or evaporate directly, with water loss from both processes combined called evapotranspiration. The water can also recharge groundwater and enter the stream later in the year. And it matters whether the precipitation falls as snow or as rain.

Climate change can affect mountain streams in two major ways: By raising the overall temperature, increasing evapotranspiration, and by shifting the precipitation from snow to rain. Both impacts could significantly alter the amount of water in a stream watershed and the amount that reaches cities downstream.

So why try to separate the influence of the two factors? “As the climate becomes increasingly more variable, we need to provide water resource managers with specific guidance on how individual warm or wet years, which may not coincide, will influence water supply,” said Brooks.

Simulated streams

The team, led by doctoral student Lauren Foster at Colorado School of Mines, constructed models of two Colorado stream watersheds on both sides of the continental divide. The researchers simulated the atmospheric conditions of a typical water year, but then applied 11 simulations of various temperature alterations to see how the watersheds responded.

In baseline scenarios, without any temperature alteration, the streams behaved as expected, with a swell in streamflow during snowmelt. During snowmelt and into summer, meltwater recharged the underlying aquifer, which then sustained streamflow through the fall and winter.

When precipitation was changed from snow to rain, the stream system became “flashier,” the team writes, with the water that would have been stored as snow running off into the stream faster. Overall streamflow in this scenario decreased by 11 percent in the watershed east of the continental divide and by 18 percent west of the divide.

But warming the systems by 4 degrees Celsius resulted in more evapotranspiration, enough that groundwater had to support streamflow an entire season earlier, beginning in summer rather than in fall. Streamflow reduced by 19 percent in the east watershed and 23 percent in the west, suggesting that warmer temperatures may have more impact on streams than a transition from snow to rain.

“Changes in energy, which result in changes in evapotranspiration, outweighed the changes in the form of precipitation,” said Reed Maxwell of Colorado School of Mines.

The effects of these two climate change effects may vary with location, the team writes, and the results need to be checked against real-life environments. But the researchers’ work helps to make sense of the noisiness in climate data and helps scientists gain a clearer picture of the future of water, especially in the mountainous west.


6 thoughts on “Claim: How climate change dries up mountain streams”

  1. This, I’m sure can be correlated with labor dislocations in China, and the invention of the autogyro. What if it had bee invented ten years later? What effect would it have on coal production for use in India? Models are wonderful. They need to be checked against reality. What increase in temperature did the models used to promulgate the Kyoto Accord in 1989 predict for our oceans and troposphere in 2016? All the climatologists are strangely silent! I wonder why.

  2. This two page tribute to my research mentor, Dr. Paul Kazuo Kuroda (1917-2001), reveals how FEAR of worldwide nuclear annihilation in AUG-SEPT 1945 convinced world leaders to:

    1. Unite the nations and national academies of sciences on 24 OCT 1945, and
    2. Hide the source of energy in atomic bombs with “consensus scientific models”:


  3. Dr. Manuel, Are you a supporter or critic of Climategate? I can’t be sure from your writings. I am a critic, and this malfeasance has now caused doubt about ALL the conclusions of the worried climatologists, some of which may, in fact, be correct. The models, though, are flawed! I don’t know, but I did work with NOAA some years ago. I’m not a climatologist, my Ph.D. is in chemistry as is yours. Our planet has already been through global warming. The last vestiges of the glaciers disappeared from New York City ONLY 6,000 years ago. There was, I’m sure. a good reason to name the country “Greenland”, and that is a much more recent name.

  4. Jack: Just ignore Oliver. He does this on every climate-related site he can find (until he’s booted off). He’s obsessed with 1945, nuclear conspiracies, interiors of stars, and other topics that are irrelevant to the serious discussion of climate. Despite numerous complaints by readers, he refuses to stop his incomprehensible diatribes. On some climate-skeptical sites, he brownnoses with the blog owners to such a degree — by thanking them for their courage — that some of his comments are unfortunately allowed through. The sheer dullness, superficiality and repetition of his weird allegations suggest that he has become rather unhinged. His comments do a disservice to serious climate sceptics who are trying to counter, using rational and current information, the massive alarmism and confusion caused by the endless blathering of thousands of pseudoscientists, pseudoreporters and warped politicians…

  5. Although Climate change, is not my specific genre, global warming and climate change are an intricate part or even the cornerstone of globalization, and the end of our constitutional sovereignty. I do know that I have a will be called a ‘conspiracy theorist’ but so be it; The implementation of the UN agenda 21/30 … depends on the global warming and climate change false science and climate models, along with the EPAs ‘secret’ science, (we don’t know what it may be, or if it even exists), yet this is actually this administration’s ‘top priority’ because all else rests on this premise; and believe me, there is a lot in the ‘all else’ that I speak of. The climate change issues will not go away anytime soon; I agree with what The Great Walrus wrote in his characterization of Oliver, nonetheless, part where Walrus suggested that he has become rather unhinged and that his comments do a disservice to serious climate sceptics. and I agree the problem the serious sceptics have with the alarmism, confusion and manufactured division, perpetrated by pseudo reporters, I will change the part about the “warped politicians”… to Warped, liberal and establishment politicians covertly stumping for the government agenda (Now Obama’s treasonous scheme to implement the UNs Agenda 21/30. Remember, he is the one who declared that climate change is settled science, and the EPA followed by claiming it secret. This is a good post, and good comments, thanks to everyone for their input. With perhaps, the exception of Oliver. Thanks.

  6. With climate change doesn’t humidity increase, thereby slowing evaporation. Ever tried to use a clothes line in Arkansas? It doesn’t work. But I imagine that doesn’t happen and even at 100% humidity evaporation is still an issue in that model. Feed backs only occur where there is opportunity for alarmism.

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