ROCK SPRINGS — Livestock raising and agriculture in Wyoming are likely to be impacted by rising temperatures, but experts continue to debate the extent.
Average temperatures in Wyoming have increased by approximately 1.5 degrees since the mid-1980s. Continued temperatures increases can have an impact as cattle and sheep can feel the heat but have a limited ability to do anything about it.
"Animals cool down and lose heat through four processes — radiation, evaporation, convection and conduction," said Frank Mithoehner, an animal science professor from the University of California at Davis.
Radiation is when heat dissipates off an animal's body similar to the way heat radiates off a human body.
For example, Mithoehner said a person can feel radiant heat when holding a hand close to a face. Evaporation is sweating, which cools an animal's skin.
Convection is increasing the airflow around an animal's body through fans or other methods to blow away the collected heat dome. Conduction occurs when an animal lies on a cooler piece of ground.
Heat can kill animals. During a heat wave in 2006, about 30,000 head of cattle died in California. Mithoehner said the animals were not only hurt by the hot afternoons, but the heat that lingered at night and did not dissipate.
There was no real nighttime cool down for the animals' bodies to recover from the daytime heat," he said.
The increasing number and severity of heat waves in recent years has increased stress levels for livestock, Mithoehner added.
"We're seeing more and more extreme weather. That is a tendency we're seeing more and more often. That can stress animals. Similar to animals in the wild, that can impact animals' reproductive ability and their performance," he said.
Heat waves can leave ground temperatures between 120 to 130 degrees, eliminating conduction as a cool-down method. In addition, more heat and less wind reduces convection.
Nonetheless, Mithoehner said there are options for mitigating the stress which livestock animals will likely feel from a hotter climate.
For example, he said livestock can benefit from fans and more shade to cool the air around the animals and the ground beneath them.
Feedlots often did not provide shade for livestock in years past, Mithoehner said, but shaded cover may become more necessary in future years with longer, hotter summers. He said added water misting or sprinkler systems could help animals to cool down.
He also said livestock owners could introduce more heat-tolerant animals into more northerly areas that had become hotter.
"Australian cattle are more heat-resistant," he said. "You can use tropical breeds or subtropical breeds and crossbreed them into continental breeds," with cattle in hotter climates such as Texas or South Africa often having bigger ears and more humped backs to dissipate body heat more readily.
Jim Magagna, executive vice president of the Wyoming Stock Growers Association, expressed strong skepticism about Mithoehner's ideas and climate warming in general.
"We've had winters recently that have been as cold as any in the last 40 years, and some that have been warmer," Magagna said. "Most of our people would not agree that global warming is happening. It would not be advisable to bring in warmer weather cattle or tropical cattle."
He noted some cattle were brought to Wyoming from areas experiencing ongoing heat and drought, like Texas. He said those animals have not done well in Wyoming due to the cooler temperatures and higher elevation.
"Cattle are heavily impacted by year-to-year climate changes," Magagna said. "We're just coming out of a six- or seven-year drought to this year with record moisture. The industry is always being affected by year-to-year changes and always has been. Over the 150-year history of the cattle industry, in 1887, the cattle business was nearly wiped out by the big blizzard that year."
One aspect of agriculture which may benefit from warmer temperatures in Wyoming is the crop-raising industry.
Jim Krall, a UW professor of plant science, said adaptive research could lead to new potential crops, including an increased emphasis upon winter wheat.
He does some work at an experiment station in Lingle.
Crops produced in warmer climates may not produce as high of protein levels, though, Krall said.
"Maybe we can sort that out by plant breeding," he said.
For example, Krall said a 2010 Australian research report documented that crops grown under higher carbon dioxide levels — 550 parts per million versus 385 parts per million — gave an average 50 percent greater harvest yield.
However, the study added this was not true of all crops. It said sorghum and other crops with more efficient carbon capture capability did not show increased yields.
The Australian study also included a warning about the impact of water availability on crop growth in a warmer climate.
"The research on this topic also shows that temperature and water availability could affect the response expected to high carbon dioxide," the study said. "The actual impact of higher temperatures and reduced water available may in fact reduce any growth benefit from the high carbon dioxide."
UW Professor Bryan Shuman, who teaches geology and geophysics, said the state could be experiencing climate change even if the population largely questions climate change.
Shuman's research paper dated Feb. 10, 2011, said, "Wyoming provides more fossil fuels to the remainder of the United States than any other state or country, and its citizens remain skeptical of any anthropogenic (human caused) influences on their climate. However, much of the state including Yellowstone National Park and the headwaters of several major river systems, may have already been affected by rising temperatures."
Shuman said the warming seen in the Wyoming climate since 1978 cannot be explained simply by solar changes or oceanic influences.
Axel Garcia, a UW agriculture professor and irrigation specialist, said it may not be necessary to change what types of crops are planted, but it may be necessary to plant crops earlier in the year, since the availability of water later in the summer may be questionable.
Garcia predicted by the end of the 21st century, temperatures in Wyoming may range anywhere from 3 to 9 degrees warmer than at present.
"We may have much more variable weather," Garcia said. "We may see cycles of drought more often and more melting of snow. We may get more rain, but it usually happens when we don't want it. Planning ahead for irrigation will be much more important, so that we have the water we need for crops."