America always has been vulnerable to droughts.
A prolonged drought from 800 to 1000 A.D. destroyed the classical Mayan civilization. Whole cities were abandoned.
Sometime in the last quarter of the 13th century similar weather conditions destroyed the Anasazi civilization in the U.S. Southwest.
Costa Rica is reeling today under a drought that is unprecedented in historical times. The Anasazi and the Mayas did not know the cause, but today scientists point to El Niño, an unusual slug of warm water in the distant Pacific.
The World Meteorological Organization expects El Niño to strengthen and peak by the end of the year. “Typically El Niño events peak late in the calendar year,” said the U.N. agency in a summary Tuesday.
Surface water temperatures in the east-central tropical Pacific Ocean are likely to exceed 2 degrees C above average, potentially placing this El Niño event among the four strongest even since 1950, the agency said, listing other strong events as those in 1972-73, 1982-83 and 1997-98.
For Costa Ricans El Niño means that Guanacaste has received rainfall this year that is from 85 to 40 percent less than normal, according to the Instituto Meteorológico Nacional. The impact on agriculture is devastating in a province that is generally dry anyway.
And the outlook does not appear to be any better. In Guanacaste, the weather institute says that the rainfall shortage will be between 40 to 70 percent and from 10 to 50 percent down the Pacific coast. The central government last year declared a state of emergency. Some towns are having their water trucked in.
By contrast, the northern zone and the Caribbean coast have been wetter. And that is expected to continue with rainfall from 30 to 60 percent above normal over the rest of the year.
El Niño has other impacts. The Atlantic hurricane season is expected to be among the mildest while the Pacific season has hit a record: There are three full-blown hurricanes in the Pacific now.
The El Niño phenomenon is expected to last through the first quarter of next year and then begin to decay, said the World Meteorological Organization, which based its estimate on previous El Niño events.