El Niño-related Droughts in the Philippines: Impacts and Mitigation Efforts

The El Niño Southern Oscillation (ENSO) is now a well-developed model to link regional climate extremes to fluctuations in sea surface temperatures (SSTs) over the central and eastern equatorial Pacific Ocean. The SST anomalies in the warm pool area of the Pacific have a strong correlation with climatic variability in the Philippines, particularly during the northeast monsoon season (October to March). An El Niño event is manifested in the Philippine local climate by drier than normal weather conditions that can last for one or more seasons, causing dry spells or even drought in many parts of the country. Weak monsoon activity, early termination of the rainy season and suppressed tropical cyclone activity near the country are other manifestations.

El Niño Impacts

During El Niño, the consistently low annual rainfall over river basins leads to a significant decrease in the water inflows in major reservoirs. Worsening decreases in inflow result in curtailment in the domestic and irrigation water supply, thus causing water rationing in residential areas and reduction in irrigated farmlands. The agricultural sector is affected by widespread water shortages induced by El Niño, which is also when crop production damage is highest, not only in upland and rainfed areas, but also in lowland irrigated areas.

The high temperature and rapid evaporation of surface water during El Niño create unfavorable conditions for marine fishes. Production losses are caused by drying of fish ponds, shorter production cycles, stunted fish growth, and fish mortalities from stress, poor water quality and disease. El Niño-related drought events are also associated with indirect environmental effects. Due to the long dry spell that moves into the otherwise wet season, forest fire destruction has steadily increased in recent years.

Mitigation Efforts

In past El Niño episodes, the Philippine government responded with each agency formulating its own action plan. This fragmented approach did not curb the effects as evidenced by the extensive losses incurred. It was recognized that the effects on agriculture, environment, domestic water supply, health and energy are inherently interrelated and called for a more coordinated approach.

The government response during the most recent El Niño (1997-98) was initiated by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA, Weather Bureau) through the issuance of a monthly weather outlook by the National ENSO Early Warning and Monitoring System (NEEWMS). The NEEWMS is an enhancement of PAGASA’s Drought Early Warning and Monitoring System (DEWMS), the objective of which is to provide timely assessments of weather conditions and other information needed by various end-users, particularly policy decision-makers and those concerned with crisis management. The assessment of various weather elements and developments in the global climate system make possible the early detection of an impending extreme climate event. Advisories are immediately issued to the public to mitigate adverse impacts even before an event occurs.

PAGASA’s early warning of the 1997-98 El Niño episode alerted the public and government to better prepare them for the anticipated effects. Before the warming event reached its peak, the Office of the President of the Philippines issued a memorandum creating the Task Force on the El Niño Phenomenon, an interagency body of representatives of sectors that might be affected by El Niño. Together, the eleven members formulated action plans for strategic programs to help the populace cope with the phenomenon and to minimize its disastrous effects. A Comprehensive Action Plan included government interventions to forewarn, educate and direct both government and private sector mitigation efforts. This was complemented by intensive tri-media information and education campaigns. The comprehensive program centered on measures that affected the agriculture, domestic water supply and environment sectors. The program likewise called for an analysis of past El Niño episodes and identification of potential crisis areas. 

Dr Aida Jose is Chief, Climatology Branch, PAGASA, and can be contacted at cab@philonline.com.ph