Monday, August 3, 2009

Forecasting Advances Help Nations Adapt to Climate Variability

(Alerted governments, industries can prepare for damaging effects of El Niño)

This is the second in a series of articles about the El Niño climate phenomenon and its effects on global weather and ocean conditions.

By Cheryl Pellerin [Science Writer]

Washington - As the fledgling 2009-2010 El Niño warms the waters of the central and eastern tropical Pacific, weakens trade winds and modifies tropical rainfall patterns, some regions that are most vulnerable to this climate phenomenon are doing something that only recently has become possible. They're preparing for it.

The U.S. National Oceanic and Atmospheric Administration (NOAA) announced the arrival of El Niño July 9, citing observations by scientists from its National Weather Service Climate Prediction Center that weekly sea-surface temperatures in the eastern equatorial Pacific were at least 1.0 degree Celsius above average at the end of June.

"Those warm temperatures meet the threshold for what we define as El Niño," meteorologist Gerry Bell, NOAA's lead seasonal hurricane forecaster, told

El Niño events occur every two years to five years and last about 12 months. They often intensify between July and September and peak in the Northern Hemisphere in early winter. (See "El Niño Climate Event Begins to Influence Global Weather, Oceans (



The ability to forecast El Niño and its cool-water counterpart La Niña is a relatively recent scientific accomplishment.

"Back in the early 1980s, there was a major El Niño under way, the 1982-1983 El Niño. Many scientists were arguing whether it was even there, even after it was very strong," Bell said. "We didn't have the monitoring capacity and the tools that we have now - the satellites, ships and buoys. All of these things help us to see not only the ocean temperatures but also the corresponding weather patterns."

Scientific knowledge of El Niño has grown tremendously since the late 1980s, but especially since about 1995.

"In 1997, when we had a very strong El Niño," Bell said, "we saw it developing in June and were already putting out forecasts for the next winter. That was pretty much revolutionary at the time - to be able to say something with that much confidence that far ahead."

The climate variability that accompanies El Niño and the climate change it is beginning to promote worldwide can cause abrupt floods, droughts and tropical storms. Such disruptions can take a major toll on a country's economy if a significant part of its economic activity is sensitive to weather and climate.

But scientists now can warn some vulnerable populations of an impending El Niño event several months in advance, giving them time to try mitigating its worst effects.

"Advanced climate science allows us to alert industries, governments and emergency managers about the weather conditions El Niño may bring," NOAA Administrator Jane Lubchenco said in a July 9 statement, "so these can be factored into decisionmaking and ultimately protect life."


During an El Niño, much of the Philippines, a southeast Asian country in the western Pacific Ocean, experiences moderate-to-severe dry periods that can last for a season or more. This takes a toll on the Angat reservoir, which provides nearly 100 percent of the water supply for metropolitan Manila's 11 million people, irrigation for 30,000 hectares of rice and 248 megawatts of hydropower for the island of Luzon.

Since 2003, with funding from NOAA and the U.S. Agency for International Development (USAID), scientists from the International Research Institute (IRI) for Climate and Society have worked with Philippine government agencies, the meteorology service and the National Water Resources Board to use leading-edge climate information, like seasonal forecasts of reservoir inflow, to manage the effects of climate variability.

IRI, established with funding from NOAA in 1996, is a member of the Earth Institute at Columbia University in New York.

Working together, IRI and meteorologists from the Philippine Atmospheric, Geophysical and Astronomical Services Administration have made progress in predicting the onset of the summer monsoon.

The meteorology service has received training in regional climate modeling and learned to use an IRI climate predictability tool to forecast Angat inflow based on global climate models.

"This project involved significant engagement with the institutions using forecast information," IRI senior staff associate Esther Conrad told in a July 20 e-mail, "and has resulted in tools that Angat managers have been trained on and are ready to use."

With the National Water Resources Board, IRI developed a reservoir model that integrates seasonal climate forecasts with the reservoir-management decision process and a digital interface that lets users visualize probability curves associated with different water-availability scenarios.

"It's one thing to have the technical capability or scientific understanding to say, we have an El Niño and that's likely going to influence the weather or seasonal rainfall in these places around the globe," IRI climate research scientist Bradfield Lyon, part of the Angat team, told "That's great for scientists to know. But if people on the ground have some awareness of that, they can take proactive measures to mitigate the consequences."

Lyon said IRI is planning to reproduce in other countries the lessons learned in the Philippines.