California could be next.

• Position: Natural Disasters - Brief article

In 2005, the Gulf Coast felt Mother Nature's wrath; now, it may be California's turn. If the world continues to burn greenhouse gases, warn researchers at Lawrence Livermore (Calif.) National Laboratory, the West Coast may have an increased risk of winter floods and summer water shortages, even within the same year.

The predictions assume atmospheric carbon dioxide concentrations double from preindustrial levels. The amount of water flowing in California's rivers needs to be just right--too much brings a risk of flooding; too little causes reservoir levels to drop.

As temperatures warm as a result of carbon emissions, more rain than snow falls at higher elevations. For the areas that do receive snow, melt occurs sooner. The research shows that this well-known scenario--in which global warming causes an increase in wintertime river flows and a reduction in spring and summer flows--is more robust than previously thought.

"It seems unlikely that any changes in...