By Stephen Leahy *

UXBRIDGE, Canada, Oct 11, 2011 (Tierramérica)

La Niña is back less than three months after the end of its last appearance, a particularly strong event that contributed to driving up global food prices.

The new La Niña will continue the largely dry conditions in important agricultural regions in Brazil and Argentina as well as the southern United States and hurt yields of soy and wheat, experts say.

“Multi-year La Niñas are not uncommon,” said Jeff Masters, co-founder and director of meteorology for Weather Underground, the web’s first commercial weather service.

“The last was between 1998 to 2001 with a few months of neutral conditions like this year,” Masters told Tierramérica.

La Niña and El Niño are, respectively, the cold and warm phases of the famous El Niño-Southern Oscillation (ENSO), a cyclical climate phenomenon that affects weather patterns around the world.

ENSO is part of the system that regulates heat in the eastern tropical Pacific Ocean and is driven by changes in surface ocean temperature and air pressure.

“ENSO is undoubtedly being affected by climate change,” said Masters.  Continue reading →