OREM — In a recent Introduction to Environmental Management class at Utah Valley State College, the professor, Jim Callison, mentioned global warming when he explained how water can become polluted when it runs through old mining tunnels.

Most rock contains sulphur, and if a mining tunnel is drilled close enough to the water table, water can run out of the tunnel — even after the mine is closed — and become toxic, acidic and have a high metal content.

Such is the case with the mines in Leadville, Colo., and to an extent with the mines in Park City. That is not the case in Utah's Tintic Mining District near Eureka, because the area is dry and the water table is lower than the mining tunnels.

But if the climate changes, Callison explained, and the area becomes humid, toxic water could begin running out the tunnels.

Callison's mention of global warming in his courses has become more frequent since he began teaching at UVSC in 1994.

"We talk about it in some depth," he said. "I'm old enough where there were past years when it wasn't such an issue. I still remember the '70s, when we were all going to freeze to death. The magazines, Time, had stories about how it's cooling."

In college classrooms throughout Utah, students are hearing more than they did five years ago about global warming — the theory that greenhouse gases such as methane and carbon dioxide blanket the upper atmosphere, which keeps warm air hovering over the Earth and prevents nightly cooling. Most scientists believe the Earth's temperatures are rising because of the so-called "greenhouse effect."

Hurricane Katrina and Al Gore's recent movie, "An Inconvenient Truth," may have forced the topic to the front pages of the popular press, but Tim Garrett, a meteorology professor at the University of Utah who researches global warming's effects in the Arctic, said scientists have been hypothesizing that human activity could cause climate change for 200 years.

"The first calculations were 100 years ago," Garrett said. "The idea is not very complicated, and it has been around for a long time. The big change now is just that the amount of carbon dioxide in the atmosphere, it's something like 300 billion tons from us, which is a lot. The amount is so much larger than it used to be. We have started to see the effects of this."

Garrett said he began teaching global warming four years ago.

While discussion about global warming in college classrooms may be increasing, attitudes are changing at a slower pace, said John Sohl, a Weber State University physics professor who has been discussing global warming in honors and astronomy courses for 15 years.

Sohl notes that in Utah, the public could only see Gore's movie at a limited number of specialty theaters. Last spring when he taught 140 students in three sections of an elementary astronomy course about global warming, "a handful came up to me afterwards," he said. "There were some questions as to what fraction believes global warming is (a natural Earth process) and what fraction believes it's human-caused. All the evidence right now, I said, is the majority of scientists believe global warming is human-caused."

Critics of global warming, such as Patrick J. Michaels of the Cato Institute and University of Virginia, are also publishing books that also question the theories about global warming held by most scientists.

"There was this book that basically tries to say that global warming is just a hoax," U. meteorology professor Thomas Reichler said, referring to Michael Crichton's 2004 novel, "State of Fear."

"It's a terrible book, in my opinion," Reichler said, laughing.

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