Sunny afternoons in October are an anomaly in Costa Rica, but this month the Central Valley has seen its fair share of them. Combine them with heavy rains along the Caribbean coast and drought-like conditions in the northwestern Guanacaste province and you’ve got what scientists are calling wacky weather produced by the climatic phenomenon El Niño.
Since July, El Niño has been causing “a very irregular distribution of precipitation” along with higher temperatures across the country, explained National Meteorological Institute (IMN) director of forecasting Werner Stolz.
What exactly is El Niño? It’s a weather pattern that occurs when the water temperature in the Pacific Ocean surrounding the equator increases by one-half a degree Celsius for a five-month period or longer, Stolz explained.
Conversely, sister weather pattern La Niña occurs when this water temperature decreases by one-half a degree Celsius for five months or more.
During the past year, Costa Rica has seen weather indicative of both La Niña and El Niño, Stolz said, though neither has been officially recorded because temperature changes have not been sustained for five months.
In March, at the end of the dry season, meteorologists predicted that La Niña would produce cooler ocean temperatures, leading to a rainier wet season than usual (TT,March 31).
However, the second half of the year’s weather has proved them wrong. In July, Pacific Ocean temperatures began heating up, resulting in air temperatures about two degrees Celsius warmer than average as well as less rain than usual all over the country, particularly in Guanacaste, Stolz said.
Last month, Guanacaste saw “extreme dryness,” meaning 30% less rain than average, while the Central Valley and north-central zone experienced “dry” weather (20% less rainfall than usual) and the Caribbean coast saw normal rainfall, according to a report published by IMN.
However, October, typically one of the rainiest months of the year, has proved true to its reputation, Stolz said, at least in the Caribbean and along the Pacific coast, which experienced flooding this week.
Thousands of residents from Guanacaste to Golfito were hit with intense and sustained rains last weekend, and damage to aqueducts left approximately 9,000 people without potable water for several days, according to the National Emergency Commission (CNE).
Overall, 42 communities suffered infrastructure damage caused by the heavy rains; five bridges and two aqueducts were destroyed, according to a statement from the commission.
During what’s left of the rainy season, which usually lasts until November, the country is likely to see continued heavy rains along the Caribbean slope and more dry weather in the Central Valley and Guanacaste, Stolz told The Tico Times.
As for the upcoming dry season, Stolz predicts hotter-than-normal temperatures through the first three months of 2007.
This abnormal weather has not only meteorologists, but also farmers and the National Emergency Commission (CNE), concerned about its possible effects.
“In terms of the whole year, there is a poor distribution of rain, and a below-average accumulation of rain that creates the perfect conditions for fires,” especially in Guanacaste, Stolz said.
Production Minister Alfredo Volio predicted that the sugarcane, livestock, fishing and banana industries are likely to be affected. Rice growers in Guanacaste recently reported 30-40% of their crops affected by drought-like conditions, according to the daily La Nación.
Dry weather can lead to plagues of rats, while wet weather helps bacteria and harmful insects propogate, Volio said.
The Production Ministry (MIPRO) has created a commission to plan for these effects, the ministry announced at an Oct. 5 press conference.
The commission, made up of representatives from the ministry, CNE and IMN, is working on contingency plans to “keep these problems under control and work hand in hand with the agriculture sector to mitigate the possible effects of El Niño,”Volio said.
Taking an inventory of the country’s livestock feed, forming regional committees and strategizing to move cattle if necessary are among plans the commission is discussing.
Global Warming and El Niño
With former U.S. Vice-President Al Gore’s movie “An Inconvenient Truth” sparking international dialogue on planetary climate changes (TT, Oct. 13), Costa Ricans may naturally wonder about the link between global warming and the country’s unseasonably warm weather.
Stolz said a link is “possible,” but he is not convinced of it. Another scientist at Universidad Nacional (UNA) in Heredia, north of San José, said the connection is undeniable. What they agree on is that El Niño and La Niña are nothing new – they have been occurring for thousands of years.
However, UNA chemist Germain Esquivel said an increase in greenhouse gases in the atmosphere is causing these weather patterns to occur more frequently.
“It’s a scientific fact that an increase in certain gases causes a warming of the atmosphere. This increased with the industrial revolution around the 19th century,” Esquivel said. “In general, the temperature of the Pacific Ocean is related to the temperature of the land, meaning that, yes, El Niño would be related to global warming.”
Stolz, however, said El Niño and La Niña are occurring with the same frequency they always have. The difference is that modern-day science means they are recorded better, he said.