Think of it as Mother Nature's roller-coaster ride: the shift between the weather patterns known as El Nino and La Nina that, at their worst, can cause havoc worldwide.

El Nino — spurred on by a warming of the equatorial Pacific — has dried up rice crops across Southeast Asia, cocoa fields in Ghana, coffee in Indonesia and sugar cane in Thailand since last year. It contributed to the Western Hemisphere's strongest hurricane on record and the planet's warmest year since at least the 1880s.

Now the ocean's surface is starting to cool, which may signal the start of a La Nina. Scientists say this pattern typically contributes to more hurricanes in the Atlantic, drought in Brazil and heavy rain in Indonesia and India. While it might give a boost to U.S. natural gas, it could hurt Australian coal operations and palm-oil output in Malaysia. For some areas, it may be worse than a typical El Nino.