A decade ago, global warming was an idea that was largely theoretical. But a recent report by the U.N.-sponsored Intergovernmental Panel on Climate Change (IPCC) makes it clear that global warming has begun. Over the past century worldwide temperatures have climbed more than 1 degree F, and the 1990s were the hottest decade on record. The result is a laundry list of changes that scientists have recorded. For instance: the annual melt season in Antarctica has increased up to three weeks in just 20 years; the legendary Mount Kilimanjaro has lost 75 percent of its ice cap since 1912, and scientists believe it could vanish from Africa's tallest peak within 15 years. Beyond melting snows and rising ocean levels, coral reefs are dying off as ocean waters grow warmer, and drought is the norm in parts of Asia and Africa.

Such facts have convinced scientists that global warming is no longer just theory. In fact, they say, temperatures may be rising faster than anyone expected. Since the start of the Industrial Revolution, humans have increased the concentration of carbon dioxide in the atmosphere 30 percent, and each year the rate of increase grows faster. By 2100, the IPCC says, average temperatures will increase between 2.5 degrees F and 10.4 degrees F. That's more than 50 percent higher than predictions made just six years ago.

Scientists, of course, can paint a pretty scary picture about the type of world our grandchildren will live in. And we're justified in harboring more than just a little skepticism about the demise of planet Earth. After all, cyclical climate trends have been the norm for millions of years. But unlike past shifts in the global climate is the human factor. With more than 6 billion of us now occupying the same rock flying through the universe, it's only logical that we've had some impact on our own nest.

Agriculture has come under criticism by environmental groups as destructive to our environment and as a major contributor to global warming. I'm pretty skeptical about those claims, too. But even if they're true, my response to environmentalists is that it's hard to live on clean air alone. However, I realize we can't be too smug about our industry-especially with the large number of people now rushing to the country to make ranching their new career.

As Time magazine reported (April 23, 2001), ranchland in the Texas Hill Country has escalated in value by 300 percent to 500 percent in the past decade. It's a hotspot for tech millionaires to build lavish getaways-raising a few buffalo, emus or cows in the process. Texas A&M University, bombarded by questions from first-time ranchers, has launched an Urban Rancher Web site to teach the basics from septic tanks to wildlife feeding. Neil Wilkins, a wildlife biologist at A&M, was quoted in Time: "All the time I hear they want to restore the native habitat with buffalo and bluebonnets. They call and say, 'I've already cleared the brush, now what?'" Of course, they've destroyed the very habitat that attracted wildlife.

One of the new "windshield ranchers" as Time described them, flies in by charter jet from Houston to a 200-acre ranch outside Kerrville. When he couldn't conquer the seaweed in a newly created lake, he tried carp, then chemicals, and finally filled it in with concrete. Another couple bought a lavish ranchette and spent millions expanding the house (to 8,600 square feet) and barn (to 28 stalls with a covered riding ring).

Such reports make it easy to believe the scientists who authored the global warming report when they tell us that with just 4 percent of the world's population, the United States produces 25 percent of the world's greenhouse gases. Your new neighbors, those with the new SUV and the pocketful of cash, are contributing more than their share to global warming-and hurting the image of all of agriculture in the process.