The future looks warmer for many major cities, that's clear—but perhaps you missed the part where it's also forecast to look wetter. Scientific measurements show that the quantity of rainfall that fell on the Northern Hemisphere intensified in the second half of the 20th century. At least some of that increase can be attributed to anthropogenic climate change, according to a recent study.

Economists, scientists and urban planners are increasingly documenting the growing risks of flood to city dwellers. Perhaps the greatest moment of awareness of this trend, at least among urban leaders, came when the storm waters of 2005's Hurricane Katrina washed away an aging and inadequate infrastructure to devastate New Orleans.

Check out this online tour of recent floods to see how vulnerable even well-planned and highly developed cities and towns can be.

» View a slide show of recent floods that might be a window to our frequently flooded future.