Have you ever read anything good about global warming? Why is all the news always bad?

Objectively speaking, any environmental change should have both positive benefits and negative effects. For example, theory predicts and observations confirm that human-induced warming takes place primarily in winter, lengthening the growing season. Satellite measurements now show that the planet is greener than it was before it warmed. There are literally thousands of experiments reported in the scientific literature demonstrating that higher atmospheric carbon dioxide concentrations — cause by human activity — dramatically increase food production. So why do we only hear one side about global warming?

Perhaps because there’s little incentive for scientists to do anything but emphasize the negative and the destructive. Alarming news often leads to government funding, funding generates research, and research is the key to scientists’ professional advancement. Good news threatens that arrangement.

This is the reality that all scientists confront: every issue, be it global warming, cancer or AIDS, competes with other issues for a limited amount of government research funding. And, here in Washington, no one ever received a major research grant by stating that his or her particular issue might not be such a problem after all.

A recent story is typical. Two American scientists, Thomas Knutson and Robert Tuleya, published an academic paper forecasting an increase in the power of hurricanes (typhoons) because of global warming. Specifically, they used a computer model in which the sea surface temperature was warmed, and they found that nearly 60 percent of the changes in the computer’s hurricanes could be attributed to that effect.

The real world is not the world of the computer. In reality, only 10 percent of the behavior of hurricanes in the Atlantic Ocean (where there are the best long-term records) is related to sea surface temperatures. When that is factored in, any changes in hurricanes related to global-warming become undetectable over the next century.

How could there be such a disconnection between a computer simulation and reality? Why don’t scientists check for this before they publish their papers? And why don’t other scientists who peer-review the research papers point out inconsistencies before they are published?

Computers only do what they are told, and they don’t do what they are not told. One factor that was ignored in this study is global warming is likely to increase winds, several kilometers aloft, that actually destroy hurricanes. In fact, as the planet has warmed, maximum winds measured by hurricane-research aircraft in the Atlantic Basin have declined.

This tempering effect of upper-atmospheric winds on hurricanes is one reason that oceanic heating explains so much less of hurricane behavior in the real world than it does in the computer’s imagination.

There’s no need to single out the recent hurricane story. There are plenty of similar examples concerning global warming.

How many times have scientists stated publicly that human-induced global warming is destroying the glaciers of Africa’s Mt. Kilimanjaro? Again, a larger constellation of facts changes the story.

There were two periods of global warming in the last century. The first ended around 1940 and was caused by the sun’s warming up. Temperatures then cooled slightly, until the early 1970’s, before warming again. Scientists believe this second heating was largely caused by the burning of fossil fuels, rather than a change in the sun.

In the first warming, 45 percent of Kilimanjaro’s ice cap disappeared. When the planet subsequently cooled, it lost another 21 percent. In the recent warming, another 12 percent has gone, the slowest rate of loss in the last 100 years. Some 4,000 to 7,000 years ago, the earth was a degree or two warmer than it is today, and yet Kilimanjaro’s glaciers were greatly expanded compared to the current era.

The fact is that Kilimanjaro’s glaciers vary greatly, with or without global warming.

And there are dozens of other stories where scientists exaggerate global warming, ignore its positive aspects, and where the media only report the bad news. In August 2000, the New York Times headlined on the front page that “The North Pole is Melting” and that “the last time scientists could be certain that the Pole was awash in water was more than 50 million years ago.”

It turns out that two United Nations scientists were onboard a Russian icebreaker serving as a tourist ship when they encountered water at the North Pole. They told this to the newspaper without bothering to check the historical record. Open water is occasionally found at the North Pole at the end of summer. The Times ultimately retracted the story — but that retraction appeared far away from the front page.

Why didn’t the polar scientists check first before calling the paper? And why didn’t the New York Times check the facts before publishing? The answers are obvious. Stories like this sell newspapers and generate government research grants. There’s no incentive in telling the larger truth, not for science, not for the media, and certainly not for those public officials who lavish funding on global warming science.