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Water

Climate change difficult on a local level in Wyoming

Written by Christy Hemken
    The climate in Wyoming and the importance of spring storms to the state’s water supply make it extremely difficult to forecast.
    “River forecasters with the National Weather Service and the National Resources Conservation Service have shown the two hardest places in the western U.S. to forecast are the North Platte Basin and the Powder/Tongue drainage,” said Wyoming State Climatologist Steve Gray in a report to the Wyoming Game and Fish Commission mid-March.
    Because of that, and because of Wyoming’s susceptibility to changes in climate, Gray said land managers and biologists know enough now to understand the need to start better planning for climate variability.
    “Multiple factors make the state of Wyoming especially vulnerable to climate change, and the biggest reason is Wyoming’s desert climate,” said Gray.
    Seventy-one percent of Wyoming averages less than 16 inches of precipitation per year, which puts the state in company with others like Nevada, Arizona, Utah and New Mexico. The national average precipitation is 27.74 inches per year.
    Seven percent of land area in Wyoming reaches 32 inches of snow water equivalent precipitation above 10,000 feet in elevation. “All of our eggs are in one basket,” said Gray. “If anything happens to that snowpack in a small area, like the North Platte Basin, there will be implications far on downstream.”
    “The earth’s climate as a whole is changing, and that’s illustrated in terms of global average temperature,” noted Gray. “All thermometer measurements throughout the world average a small increase in temperature - about one degree over the last 100 years – and that’s a consistent result.”
    “To increase the average temperature of the entire earth means there’s a massive change in the energy balance of the entire earth,” said Gray. “Think of how long it takes to heat up just one of our reservoirs.”
    Gray said the same group of 2,500 scientists that concluded there’s a 99/100 chance that global temperature is changing also said there’s a nine in 10 chance this warming is caused by human activity.
    However, at the recent Good Neighbor Forum held in Cheyenne, Smithsonian-Harvard Institute physicist Willie Soon said he disagrees.
    “The amount of carbon dioxide in the air is not controlled by our emissions, but rather by temperature and other biological and chemical factors,” he said. “This comes in sharp contrast to the picture offered by the UN and other scientists – it’s a false premise.”
    He said carbon dioxide emissions from burning fossil fuels pale in comparison to natural processes. Fossil fuels produce 5.3 billion tons of carbon dioxide per year, but cattle alone emit 50 billion tons, and oceans can emit 90 billion tons per year.
    “Another important way to think about how small the man-made portion is, is to think about the small fraction of soil that can emit 5.3 billion tons of carbon dioxide per year,” said Soon.
    In addition to the point that fossil fuels have a very small impact on global carbon dioxide levels, he said, “There is a very closed relationship between temperature and the level of carbon dioxide in the air. Carbon dioxide does not drive temperature, it is temperature that causes the carbon dioxide change.”
    Soon said if you accept the argument that increased carbon dioxide levels cause a higher global temperature, you’re agreeing that lung cancer causes smoking.
    “In all cases in history, it has always been the temperature that warms first, and then carbon dioxide responds,” he explained. “If you think that fact is not important, we might as well not have science. The principle of causality is the fundamental essence of science.”
    Regarding local effects of global climate change, no matter the cause, Gray said, “What really matters is what’s going to happen at the level of our state and within regions in which we’re interested. That’s where the story gets more complicated.”
    Although scientists haven’t yet determined how much precipitation will change, Gray said there’s a strong indication the western U.S. will warm between four and seven degrees.
    “The difference between 68 and 72 degrees doesn’t seem important sitting in your living room, but four degrees can be the difference between a sagebrush steppe in the lowlands and pine ridge above,” said Gray. “Then it gets a little more important.”
    He says change in temperature would affect spring runoff, as it already has. “The state has been snow-free a month earlier than expected based on historical observations, and we may get the same amount of runoff, but it comes off faster and gives us less at the end of the season.”
    Gray said when the Palmer Drought Index was recalculated with a slight increase in temperature and exactly the same precipitation as today, the result was average conditions in the next 30 years being as bad as the 1950s drought.
    Referencing the tree ring studies conducted across the West, Gray said, “Even if we don’t see human-caused climate changes, we better start incorporating climate variability into our management because it’s bound to happen anyway.”
    According to the tree studies, there are a number of examples where average conditions for 40 years were significantly lower than the worst droughts of the 20th century. “We’re talking about the loss of two million acre-feet of water on average in some of these systems,” said Gray.
    He pointed out in the last 500 years there were massive shifts in the climate before humans could have possibly interfered. “In the late 1600s there was an extended drought that left only nine million acre-feet of water in our system, but in a year or two it was back up to 18 million on average. That’s a massive swing that causes some major problems in terms of managing water in this system.”
    “We’re in a new game here,” said Gray of habitat and water management. “If we’re extending the warm season we’re in new territory.”
    Christy Hemken is assistant editor of the Wyoming Livestock Roundup. Send comments on this article to This email address is being protected from spambots. You need JavaScript enabled to view it..