Santa Ana, Bolivia, February 13, 2008—A rancher herds cattle away from floods.

Bolivian President Evo Morales this week declared a national disaster, and officials said the devastating floods have killed scores since November and affected tens of thousands, the Associated Press (AP) reported.

A rainy season aggravated by La Niña—a periodic cooling of waters in the Pacific Ocean—has hit hard all across Bolivia, the AP reported.

Some scientists believe higher ocean temperatures caused by global warming boost the amount of moisture in the air and cause the El Niño weather pattern—and its echo, La Niña—to occur more frequently and cause more intense climate disruptions.

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