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Cautionary signal

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Cautionary signal

/ 01:22 AM October 11, 2014

Don’t be lulled just yet by the downgrading of El Niño by the Department of Science and Technology. The peak is just ahead. Beefed-up sustained response for rougher threats in the years to come is more urgent than ever.

That cautionary note comes from hydrologist Pedro Walpole, who heads the Institute of Environmental Science for Social Change based in Ateneo Loyola Heights. Walpole is a Jesuit priest.

Many thought the threat was over. Not so. Although weaker, its effects here will peak next month. A fading El Niño can still affect the harvests of small farmers who constitute an overwhelming majority. Many have no fallback source for their next meal.

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We understand better now the time lag between when El Niño is declared in the mid-Pacific and when it slams into, say, Mindanao’s Bukidnon, writes Dr. Wendy Clavano of Environmental Science for Social Change. That lag comes roughly to 197 days.

Analytical tools, like the standardized cumulative precipitation index of available water in natural systems in Mindanao, have been crafted and make such estimates possible.

Clavano earlier tracked rising sea levels in the Philippines. They will be highest along the Pacific seaboard. That slices from Samar to eastern Mindanao, the Zamboangas, plus the provinces of Romblon and Marinduque in the Sibuyan Sea.

El Niño will possibly have a lesser impact on the Agusan valley in eastern Mindanao because there is more available ground moisture, Clavano writes. But it will have a stronger impact on Bukidnon where there is more cropland on a plateau, with the rivers set in deep canyons.

Take a typical upland Bukidnon village like Bendum. Its annual average rainfall is 2,240 mm. The impact of El Niño, as presently calculated, translated to a 30-percent deficit of 364 mm by mid-April. That shortfall will be more today.

Forget cloud seeding. Costing $1,000 per flying hour, it forms one-off type of activities, useful only for the press release. The Department of Agriculture is therefore distributing shallow tube wells and drought-tolerant crop varieties, and exploring water-saving technologies. “These responses are however limited to lowland contexts. Upland situations are not considered.”

Crop alternatives have not been explained well. Slow-growing root crops such as sweet potato, cassava and yam are crucial for food security in future and more intense El Niños.

El Niño is a weather-changer, Walpole writes. We’re learning to adapt as we understand a little more of this phenomenon that impacts all continents through the atmosphere and jet stream.

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Every 20 years or so an intense El Niño hits, due to major sea temperature changes in the Pacific. The result is drought that sears much of Southeast Asia down to Australia, then on to parts of South America and Southeast Africa. The most severe droughts were in 1982-1983 and 1997-1998.

El Niño is associated with the destruction of sardine shoals off Peru (east Pacific) at Christmas when traditional Misas de Gallo or dawn Masses are celebrated. Our knuckles tighten when it emerges, second quarter of the year, 6,000 kilometers away from Peru. But it will take about three to four months before rainfall patterns are affected here. Add a few more months before a drought becomes perceptible as it spreads.

The Oceanic Niño Index is a key warning tool. If there is an ONI surge of more than 0.5 above the normal temperature, then El Niño is declared. This threshold was breached here last April, May and June, and El Niño was duly announced. In 1997, the variance was 2.38 above the average.

The warmer water of Niño 3.4 region does not reach the Philippines. But passing over the warm sea, the air slowly increases in temperature and moves westward. The winds and wind power are weakened. Typhoons are less likely to form.

A storm surge like the ones brought by “Yolanda” (Haiyan) can’t happen during the months of El Niño. That’s cold comfort because the rains have often turned disastrous. Today’s El Niño clones the 1997-1998 pattern. The threat is much less. But there is a 75-percent probability that a water shortfall may exceed 30 percent.

The rains weakened over the months, until “Mario.” The reduced rains will be most critical here next month. In other regions on earth, El Niño dumps heavy rainfall and La Niña would indicate drought. That seems the opposite of what happens here.

Why? During an El Niño, westerly winds along the equator that drive the moisture-laden air toward the Philippines weaken. Much rain falls over the open seas. The warm pool also has the energy to generate more evaporation than normal.

Rainfall supplies water to the environment depending on the speed at which it travels through the hydrological system. Moisture is essentially stored on land and becomes available at a later time.

This delay allows drought to be forecast in advance of water-supply decisions. Depending on the nature of the water resource, the distribution system in place, and primary use of the water, the lead time could be a few months. Hence the critical priority for water storage and local dams.

By the New Year, we will know the final outcome of the 2014 El Niño. It may never “arrive” in the Upper Pulangi area of Mindanao or even “Hacienda Binay” in Rosario, Batangas. The stronger the Oceanic Nino Index, the more reliable is the reading of subsequent effects.

Despite improved tracking confidence, drought forecasts remain shaky. A mild drought might even be a boon to farmers in the lowland valleys, where they grouse that they get too much rain now compared to past records.

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E-mail: juanlmercado@gmail.com

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TAGS: DOST, El Niño, Juan L. Mercado, opinion, Pedro Walpole, Viewpoint, weather
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