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Western climate examined at workshop

by Wyoming Livestock Roundup

Cheyenne – Global change, connectivity and the role of science in the West’s reaction to climate change became the highlight of an early-September symposium on climate change in Western rangelands.
    “Connectivity underlies how we think about ecology and climate change issues. Technology makes the world a very small place and ecology and the environment are connected across the globe,” said David Williams of UW to open the workshop, which was hosted by USDA’s Agricultural Research Service (ARS), Colorado State University, the Society for Range Management and the University of Wyoming (UW).
    Williams cited increases in nitrogen in the atmosphere above Sinks Canyon in Wyoming, even though the highest levels of nitrogen increase in the U.S. center over the Midwest.
    “The role of science is to generate knowledge and understanding of the natural world – it’s an unbiased assessment of the potential consequences of human actions or public policy,” said Williams. The conference focused not on why climate change is occurring, but on what land managers should do in response.
    “We know the climate as a whole is changing,” stated Wyoming State Climatologist Steve Gray, who also directs the UW Water Resources Data System. “The temperature of the globe as a whole has increased by a degree over the last century, which may not seem like much but when you consider heating the land surface and all the water on the planet we’re talking about an enormous change in the amount of heat trapped in the earth.”
    Gray said that, because of our understanding of the factors that control the climate of the earth as a whole, the changes are expected to continue for the foreseeable future.
    “Multiple lines of evidence are telling us something is up. The rate and magnitude of these recent changes is something unique to the past few thousand years,” said Gray. “We have to go back many thousands of years to events that happened as a hangover of the last ice age to see these fast responses in the global climate system.”
    “While we can’t predict the weather from day to day, we have a good understanding of what accounts for the climate of the earth as a whole,” he continued. “We can test what we know going back many thousands of years using approaches like info stored in ice cores throughout the world.”
    Scientists can use tiny air bubbles trapped in large glaciers to measure the composition of the Earth’s atmosphere in the past. Particles of dust also serve as thermometers to indicate the temperature of the planet in the past.
    Although the composition of the atmosphere is very important, Gray said it’s not the only thing taking the Earth in or out of ice ages. He said changes in solar output, orbit and tilt of the earth also played a major role in massive changes in climate.
    While all that happens on a global scale, the conference focused on predictions for what will happen to Western rangelands in the future. “We have a consensus with room for improvement, but predictions for precipitation are that in Wyoming and Colorado we’re in a break-even situation and we don’t expect much change in overall precipitation,” said Gray.
    However, he said the other part of the story is that temperatures in the western U.S. are expected to continue warming, from three to seven degrees by mid-century. Using the Palmer Drought Severity Index, predictions show drought in Wyoming as bad as the 1950s, which is the drought of record for the western U.S.
    “The Palmer Index looks as bad as anything we saw in the ‘50s because of the increase in temperature and the added evaporation in the system,” said Gray. “A little bit of temperature increase is going to have a major impact on western rangelands.”
    Gray says a more subtle consequence is what will happen to snowpack levels if Wyoming starts receiving more rain versus snow. “If things warm up we’re bound to see a change in precipitation coming as rain rather than snow, and the two don’t work their way into the hydrologic systems in the same way,” explained Gray, adding that different plants have different rooting zones that make them better adapted for water falling in different times of the year. “Will we see a change in the composition of these plant communities?” he asked.
    “As things warm up we also expand the growing season, setting the stage for things like massive insect outbreaks. We’re also drying things out, causing larger and more widespread fires,” said Gray, adding that in addition land managers are beginning to reap the consequences of management decisions made many decades in the past.
    “As the climate changes, some species will be left behind and others will be favored,” said Gray. “A shadow on all of this is what’s also happening with the introduction of exotic species, some of which may be favored by a warmer climate.”
    Gray said the bottom line is that Wyoming and the western U.S. are extremely vulnerable and susceptible no matter what the cause of warming. “A growing number of predictions tell us the future will be one that’s effectively dryer. We would have to have massive increases in precipitation to offset the effects of increasing the temperature.”
    “Many factors will play in – not just climate change,” noted Gray. “We have to think of climate change in the context of exotic species introduction and changes in land management, ownership and disturbance cycles.”
    “We know enough now to start acting on the information we have available,” he said. “By ‘acting’ I don’t mean changing light bulbs. We already know enough to start planning for the future we’ll deal with.”
    He said the most important part is that adaptation to change does not depend on the cause of those changes. “We recognize the western U.S. is changing, and it doesn’t matter what the cause. We know we have to adapt to it, and that’s the story as it stands.”
    Christy Hemken is assistant editor of the Wyoming Livestock Roundup and can be reached at

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