Sunday, June 26, 2016

What is La Nina and what does it affect

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.

The cycles occur every two or three years on average and help regulate the temperature of the Earth as the equatorial Pacific absorbs the heat of the sun during the El Nino and then releases it into the atmosphere. That can create a La Nina: a “recharge state” when “the whole Earth is cooler than it was before this started,” Trenberth said. 

United States

While El Nino can produce a milder winter across the northern U.S., La Nina often brings chills to the Pacific Northwest, northern Great Plains and parts of the Midwest. For places like Iowa, a major source of corn and soybeans, timing is key, said Harry Hillaker, the state’s climatologist. If a La Nina occurs early in summer, there’s a chance for hot and dry weather, which can hurt the plants as they are pollinating.
Natural-gas producers in the U.S. “would really like La Nina,” said Teri Viswanath, managing director for the commodity at PIRA Energy Group in New York. They hope it will produce warmer temperatures in summer and the possibility for cooler temperatures in winter. “A cool winter, wow, that would be really helpful.”

U.K. and Europe

For Europe, the energy prospects are more muddled. From November to December, the phenomenon could mean colder temperatures and thus higher fuel demand.
“It’s also the case that we get the unfortunate relationship of lower wind speeds during that period, so that could mean we get lower wind power,” said Hazel Thornton, manager of the U.K. Met Office’s climate-change adaptation team. After the New Year, the pattern in Europe would typically flip, with temperatures becoming milder and wind increasing.


For Brazil, La Nina is more dangerous than El Nino because it hits crop production “hard,” said Eduardo Assad, a climate researcher at Brazil’s state-run agricultural research company, Embrapa. That’s because it can bring drier conditions, which also could damage the water supply, worsening Sao Paulo’s water crisis, he said.
Brazil tops the world for soybeans and oranges, and Sao Paulo is one of the cities hosting football matches for this year’s Olympic Games.


For India, La Nina “means good rains,” said Atul Chaturvedi, chief executive officer of Adani Wilmar Ltd., a refiner and retailer of cooking oils. “India has been reeling with poor rains for almost two years now, so La Nina for all practical purposes should be a boon.”
It might come too late to enhance this year’s monsoon, however, said Dave Streit, chief operating officer for the Commodity Weather Group LLC in Bethesda, Maryland.


It also may come too late to help this year’s palm-oil crop in Malaysia, with futures there rising in February to the highest in eight years.
“There is no way the emergence of La Nina, or just normal weather, will undo the damage done by El Nino,” said Ling Ah Hong, director of Malaysian plantation consultant Ganling Sdn in Kuala Lumpur. “This is something a lot of people misunderstand.”
An extreme La Nina could cause yields to fall. Flooding hurts the ability to harvest and reduces the quality of fruit, said Roy Lim, group plantations director at Kuala Lumpur Kepong Bhd., Malaysia’s third-largest producer.


For Australia, the “main negative impact” from La Nina is heavy rainfall and “a disproportionate number of major flood events,” said Blair Trewin, a climatologist with the national Bureau of Meteorology.
In 2010-2011, the pattern triggered so much rain that 85 percent of the continent’s coal production was hit by flooding. Spot prices of metallurgical coal jumped to $383 by the start of 2011 from $212 per metric ton in the third quarter of 2010, Mark Levin of BB&T Capital Markets said in a May 10 note to clients.
La Nina returned in 2011-2012, helping to boost wheat production to a record 29.9 million metric tons. It also caused vegetation to flourish in the usually arid interior -- which fueled widespread grass fires when the rains stopped.
While the world waits to see if a La Nina will develop, there’s always a chance it could fizzle. Forecasters were certain an El Nino would form in 2014, only to see it fall apart. The prediction models are better around June and July than they are now, according to Michelle L’Heureux, a forecaster for the Climate Prediction Center.