365 Days of Climate Awareness 225 – Impacts on Philippine Agriculture

The Philippines sit entirely in the tropics, and the northwest Pacific is one of the most active areas in the world for cyclones. Furthermore, the impacts of ENSO are large across the Philippine islands: La Niña tends to bring rain, and El Niño to bring drier weather. These effects have been tracked in recent years, along with fundamental variables like air and sea temperature. The resulting picture is complex.

Air and sea surface temperature trends are unambiguous, showing increases throughout the 20^th and early 21^st centuries. One of the fundamental components of climate change analysis, including the concept of “global weirding”, is that increases in heat content in atmosphere and ocean, by adding energy to the climate system, should result in more frequent and energetic storms and rainfall. And while this is to some extent true around the world, in reality the global climate response is not a simple linear increase. That is the case in the northern Pacific as well.

NOAA's ONI (Ocean Niño Index), 1951-2022.

NOAA’s Ocean Niño index (ONI)  has come to help define El Niño vs. La Niña years. It is a measure of sea surface temperature differences across the tropical Pacific, and it shows no major trend over the past seventy years, either in frequency, mean (trending toward one state or another), or amplitude (severity). The most severe El Niño years (dry for the Philippines, elevated N hemisphere temperatures) seem to be becoming a bit more so, and perhaps La Niña years (wet for the Philippines, warm water is driven by wind deeper into the ocean) are becoming more frequent.

But there is no obvious trend in cyclone count or severity in recent decades. (And let’s be clear: this is not disappointing. We’re not rooting for destruction!) But as the ocean continues to absorb more heat, any increase in La Niña activity can reflect an increase in system storage of heat, even if it is not expressed immediately through major storms. But factors can combine. Even if storm activity is not by itself notably increasing, along with sea level rise they are producing increasingly damaging floods.

Rice yields (gray), by quarter, by temperature ranges for present-day and modeled future climates.

Severe droughts tend to coincide with El Niño years, which begin to have an impact around the end of the year, during the rainy growing season for rice. During the first quarter (January-March), when the rice fields are most productive, heat has the least effect, though drought the most, on productivity.   

Tomorrow: introduction to the Maldives.

Be brave, and be well.