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Strong El Nino years to double, scientists say

Source: Thomson Reuters Foundation - Tue, 18 Feb 2014 10:23 GMT
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A general view shows a flooded church at San Roque village on the riverbank of Magdalena, Colombia, on December 17, 2011. REUTERS/Joaquin Sarmiento
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MEDELLIN, Colombia (Thomson Reuters Foundation) – Climate change could double the rate of occurrences of the strongest El Niño events, one of the world’s most destructive climate phenomena, climate scientists say.

El Niño occurs when the surface water of the Pacific Ocean warms up, changing rainfall patterns around the world. Its effects include droughts in Africa, crop losses in Southeast Asia, floods in Peru and Ecuador, and forest fires in the Amazon- problems that can represent billions of dollars in damage.

Observations show that El Niño comes every 5 to 7 years, and very strong events happen every 20 years. But a recent study published in Nature shows that 17 out of 20 climate change modeling scenarios predict that these stronger El Niño events may start coming once every decade, doubling their frequency.

“If someone tells me that El Niño is to double, I wouldn’t worry twice as much… I would worry much more,” said Germán Poveda, a hydroclimatologist at the Universidad Nacional de Colombia and a member of the Intergovernmental Panel on Climate Change who has studied El Niño and its effects in tropical countries for more than 25 years.

Colombia is tremendously sensitive to El Niño, and serves as a poster child to illustrate its effects on everything from hydropower generation to agriculture, vector-borne diseases, and river navigation, Poveda said.

Colombians still remember the nationwide blackouts and energy rationing from May 1992 to February 1993. The electric system is dominated by hydropower, and El Niño dried out the reservoirs used for power generation. The country even had to adopt daylight savings time in order to reduce electric power demand.

Such blackouts had tremendous impacts on the economy. In 1994, a new law opened generation of electricity to private investors, and over the last 20 years power regulation has been modified to ensure reliability of supply during intense El Niño-related events.

Today there are market incentives for power sources that can ensure long-term reliability, which favors the development of large hydropower and thermal power plants.

EFFECTS ON COFFEE

Some crops suffer due to lack of water during El Niño events, but that is not the case for Colombia’s most famous crop. Luis Fernando Samper, from the Colombian Coffee Growers’ Federation, said that warm, dry seasons are good for coffee production, but they do favor the appearance of “la broca” (the coffee berry borer), a small beetle that eats the coffee grain and destroys the harvest.

The beetle is a very costly pest to control, Samper said, and is one of the reasons that coffee growers increasingly tend to favour higher altitude fields. One area near Pereira – a major Colombian city – that has been afflicted by la broca and higher-than-average temperatures has seen coffee farmers move elsewhere after their yields decreased.

Bad market conditions and increasing land costs also played a role in the moves, he said, but “nowadays you can’t find any coffee in those areas.”

LA NINA?

Worsening El Niño events may not be the only worry for Colombians. Scientist say there are still no conclusive studies about the behavior of La Niña, the “cool-phase” of El Niño, caused by the intense cooling of the surface of the Pacific Ocean. This phenomenon also modifies the global weather in a dramatic fashion.

In 2010 Colombia received a heavy blow from La Niña, as extreme rainfall caused heavy flooding and some of the worst climate-linked disasters in Colombia’s history.

That year, La Niña-related floods affected over 4 million Colombians, roughly 9 percent of the population. A 2013 study by the Smithsonian Tropical Research Institute estimated economic losses from infrastructure damage, cropland flooding and government costs to deal with the problem at $7.8 billion.

Even coffee, a crop that is not located in flood-prone areas, was affected. Excess humidity in the soil and heavy rain affected the growth of coffee plants and their flowering process.

“You could see bright and green coffee trees, but there was no coffee production”, Samper said. This decline in production, along with the appearance of a fungus in coffee leaves, make Colombia’s coffee industry more vulnerable to La Niña than to El Niño, he said.

Climate modeling so far has not produced a clear scientific consensus on questions such as how long future El Niño events will last, whether the frequency of extreme La Niña events will change, and how intense La Niña events may be in the future. More study is needed, researchers say, as studies so far have produced mixed signals.

Santiago Ortega Arango is a Colombian engineer and freelance journalist interested in climate change and renewable power issues. He is an associate professor at the Escuela de Ingeniería de Antioquia. Twitter: @sortegarango

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