Current El Niño coming on strong

Climate’s “little boy” is back in a big way.

El Niño, a weather disruption caused by unusually warm seawater in the eastern Pacific, kicked off in March and could become a whopper, the National Oceanic and Atmospheric Administration’s Climate Prediction Center reported July 9. The agency predicts that El Niño conditions have a more than 90 percent chance of continuing through the Northern Hemisphere winter and around an 80 percent chance of sticking around through spring.

An enduring El Niño will alter weather around the world, including potentially causing droughts in the Western Pacific and bringing heaps of much-needed rainfall to drought-stricken California (SN: 1/10/15, p. 16). New projections released by the Climate Prediction Center July 16 suggest Californians should expect above-average rainfall in parts of the state from September through April. The ongoing El Niño has already reached “moderate” status and has more than a 50 percent chance of reaching “strong,” the highest El Niño designation, says Anthony Barnston, a climate scientist at Columbia University.

With such a strong start, this year’s event could ultimately rival the blockbuster 1982–1983 and 1997–1998 “super El Niños,” says climate scientist Kevin Trenberth of the National Center for Atmospheric Research in Boulder, Colo. “As far as I can tell, it’s currently as large as it’s ever been for this time of year,” he says.

El Niño events spawn every three to five years or so when changing wind patterns over the Pacific Ocean push a colossal pool of warm seawater eastward toward the Americas. The warmth of this shifted water alters the flow of heat and moisture around the planet. El Niño years can alter storm activity, resulting in more intense typhoons in the Pacific and quieter hurricane seasons in the Atlantic (SN: 5/2/15, p. 36). This year’s El Niño is the first since 2010. Budding events in 2012 and 2014 fizzled before they officially started (SN: 11/1/14, p. 6).

The strongest effects from El Niño usually hit during a hemisphere’s winter. Countries in the Southern Hemisphere such as Brazil and Australia have already seen reduced rainfall connected to the current El Niño. The effects will shift northward over the coming months, potentially sparking droughts in India ( SN: 9/16/06, p. 190 ) and southeastern Asia. In the United States, the Ohio Valley, Great Lakes and Pacific Northwest will probably see drier-than-normal conditions while above-average rainfall will probably wet the western Gulf Coast and Southern California.

Increased rainfall may seem like a godsend to Californians, but it still might not be enough to end the state’s ongoing drought, says Brad Pugh, a meteorologist at the Climate Prediction Center in College Park, Md. “It’ll likely take more than one wet season to overcome a drought that dates back four years,” he says.

Even with a robust El Niño, increased rainfall over California isn’t guaranteed, says Michelle L’Heureux, a climate scientist at the Climate Prediction Center. The state received below-average rainfall during the strong 1965–1966 El Niño, she points out.

Beyond El Niño’s regional impacts, the extra heat released into the atmosphere from the Pacific Ocean can spike the global average temperature, says Tom DiLiberto, a meteorologist at the Climate Prediction Center. If El Niño strengthens over the coming months as expected, both 2015 and 2016 could easily end up among the hottest years on record, he says. Future climate change could increase the frequency of strong El Niño events, and the corresponding warmer years, in the coming decades (SN Online: 1/26/15).