In 1862, California was hit by a flood of biblical proportions. In the state’s Central Valley region, the “great flood” created lakes that grew 20 miles wide and 250 miles long. It killed thousands of people and destroyed entire towns and vast tracts of farmland. In Sacramento, the state capital, the flooding forced Leland Stanford, the newly elected governor, to travel by rowboat to his inauguration.

Some scientists believe that the extreme flooding of 1862 was caused by atmospheric rivers, clouds of water vapor that carry water from the poles and deposit heavy rain or snow when they hit land. California and the western United States have been hit hard the past few winters. They are likely to be even more severe in a warming world. Western states need to prepare for this. (Alice C. Hill and Tess Turner, more at www.cfr.org)