In California, wildfires that continue to rage have killed five people, claimed 1,500 homes and forced the evacuation of nearly 1 million residents - the largest mass relocation of Americans in modern history.

Parts of the South and West are in a record-setting drought. Unless it lifts, the water supply for the city of Atlanta could run out within 90 days. Earlier this week, New Orleans got 7 inches of rain that left water waist-deep in some neighborhoods. And in New Hampshire, the odd run of hot, wet weather continues.

Extreme variations in weather are an expected result of global warming. But is that what's going on? Skeptics believe the link between these California fires and global warming has yet to be conclusively made. They're right. But skepticism shouldn't prevent people and governments from making preparations and taking precautions.

The dangers posed by rapid climate change, whether it's caused by humans or a change in cyclical weather patters, are real. By now, many people can recite them: rising sea levels, more frequent and severe droughts, wildfires and floods, species extinction, the northward spread of tropical diseases and more.

The forced migration of those displaced by the California fires could be just the beginning. Consider this: Studies by the non-profit Worldwatch Institute among others, warn that at least 21 of the world's cities with a population of 8 million or more face damage or inundation from higher seas and fierce storms. Bangkok, a city of 8 million-plus, for example, is only a few feet above sea-level and sinking at the rate of 4 inches per year. At risk are some 643 million people living in low-lying areas of a host of nations, including the United States.

The thought of relocating a major metropolis or protecting it from the sea is daunting. The cost would be enormous. But minimizing the impact of fires like those sweeping over southern California is doable. Same with preventing damage in areas guaranteed to flood or be destroyed by storms. It's not like no one knew these disasters would happen.

In June, a story in The New York Times warned that because development throughout the West continues to spread into areas known to burn periodically, losses from wildfires would continue to grow.

The most attractive places for homes, in the West or on the nation's seacoasts, are adjacent to or near public lands, and some 8.6 million new ones have built in the last 25 years. Whole towns sprung up next to fire-prone national forests. Protecting them and other development from wildfires now accounts for almost half the Forest Service's annual budget and, if development continues, will consume all of it.

Fighting wildfires costs taxpayers hundreds of millions of dollars per year, not counting disaster relief and higher insurance costs to make up for losses. Firefighters are needlessly dying to protect homes that never should have been built where they are in the first place.

Is it fair to ask public servants or volunteers to die to save someone's vacation home in a brush-filled canyon, especially when its owner didn't bother to clear the land around the structure or take other measures to reduce the risk of fire? We think not.

Most of the people living in the great metropolises threatened by the sea can't move. Most Americans who build waterfront homes in hurricane-prone areas or decide to live next to nature in the dry hills above San Diego or Los Angeles can. If the skeptics are wrong and global warming has begun making natural disasters a regular event, they'll have to.