As we went to press, devastating wildfires sweeping southern California had forced at least half a million people to flee their homes, with close to 2,000 houses destroyed. Twenty-one firefighters and at least 24 others had been injured. Several deaths were reported.

The fires, spread by winds up to 100 miles per hour, burned about 670 square miles from the Los Angeles area to the Mexican border, with San Diego County the hardest hit.

Thomas Swetnam, a forestry expert at the University of Arizona, says the increasing numbers of large forest fires and area burned in the western U.S. are “significantly correlated” with larger warming and drying trends.

Interviewed on “60 Minutes” last week, Swetnam described how it plays out: Spring is arriving earlier because of warming conditions, and mountain snow melts and runs off earlier. Logs, branches and tree needles all dry out sooner, leaving dry tinder on the ground for longer periods — thus more opportunity and fuel for fires to start.

Said Swetnam, “We’re dealing with a period of climate, in terms of temperature and humidity and drought, that’s different than anything people have seen in our lifetimes.”

Amy Luers, California climate manager for the Union of Concerned Scientists, warned that the scientific evidence “suggests that if we do not make dramatic cuts in our emissions of global warming pollution, the wildfires throughout the West could lead to dramatic changes in the western landscapes.”

President Bush rushed to look like a take-charge leader in this disaster — a former adviser called it an “anti-Katrina” response.

But the same newspapers that carried front-page photos of the flames also carried a news report that the White House had forced the director of the Centers for Disease Control and Prevention to slash scientific references to the health risks of climate change from testimony she gave to Congress this week.

Serious leadership on global warming is required, not phony photo-ops.