At least one Southeast Asian country, Thailand, declared the arrival of La Niña in early August. Others have suggested there is a 70% chance of a La Niña event occurring between August and October 2024. While crop-producing countries generally welcome the arrival of La Niña (“the little girl”), the phenomenon is usually a double-edged sword given some of the negative impacts.
The 2023-2024 El Niño event was recorded as one of the five strongest on record, bringing heatwaves and droughts, but the La Niña event will be welcomed after it. This event affected agriculture in Southeast Asia, especially rice production. The El Niño event was declared over by May 2024. Unlike El Niño, La Niña events are usually associated with cooler and wetter weather that brings favorable conditions for crop growth. La Niña events usually follow El Niño events (especially when El Niño events are considered strong), but this is not always the case.
La Niña events are characterized by abnormally cold temperatures. They usually occur approximately every 3-5 years and are caused by cyclical cooldowns in sea surface temperatures in the east-central equatorial Pacific Ocean. They can occur over several consecutive years and last from 6 to 24 months.
La Niña's impact is almost the opposite of El Niño: it can lead to intensified rain and heat patterns compared to when the El Niño Southern Oscillation (ENSO) is in its neutral phase. Some weather authorities are being cautious, with state meteorological departments in Indonesia, the Philippines, Vietnam and Malaysia monitoring the risk of potential storms and floods predicted to begin in August, and, in the case of the Philippines, an increased occurrence of tropical cyclones.
However, climate agencies warn that climate change could cause sea surface temperatures to reach record-breaking levels in 2023-2024, which could deviate from the historical global pattern of heat transfer associated with ENSO. It is therefore difficult to predict how this unusual rise in global sea surface temperatures will affect future La Niña and El Niño events. However, studies have found that these two phenomena are becoming more frequent and extreme due to climate change.
Historically, La Niña events have brought increased rainfall to parts of Southeast Asia, particularly the Philippines, Indonesia, and Malaysia (see Figure 1). Maritime countries in the region experience more rainfall from September to November and March to May, although the Philippines and Indochina experience less rainfall from June to August.
Additional rainfall coinciding with the planting season may improve soil moisture and benefit crops, but higher than normal rainfall and winds may cause flooding and more destructive storms, which may lead to loss of fertile topsoil/fertilizer, seed washing, landslides, reduced crop quality, crop destruction, or livestock deaths, depending on the stage of the agricultural production cycle.
Based on historical records, the major rice-producing countries of Indonesia, Vietnam and Thailand have often benefited from increased rice production during “strong” La Niña years (see Figure 2).
Let's use an umbrella
Figure 1: Typical rainfall variations over Southeast Asia for September-November, December-February, March-May, and June-August based on limited historical La Niña events (1979-2021).
Source: Singapore Meteorological Service
Increased rice yield (normal)
Figure 2: Rice production (in million tonnes) overlaid with La Niña and El Niño periods for Southeast Asian countries from 1995 to 2022. Stars indicate years with increased production.
Source: FAOStat, GGweather
Note: 2020-2021 has been unusual due to Covid-19 related production impacts.
There may be adverse environmental, social and economic impacts, especially in areas affected by last year's strong El Niño. This is likely to affect productivity in subsequent cropping seasons. For example, soils compacted by heat waves and drought in 2023-2024 may have limited capacity to absorb rainfall and increase runoff, causing flooding. Farmers, already suffering economic losses from reduced yields, may find it difficult to buy enough seeds and other inputs for the next crop cycle. This could limit farmers' ability to maximize benefits from La Niña.
La Niña typically impacts global supplies of staple grains by bringing dry weather and low yields to Argentina (affecting corn, wheat, and soybeans) and Brazil (affecting corn and wheat), both major exporters of affordable grains. However, this reduction can also be offset by agricultural gains from better weather in China, India, Australia, and parts of North America (see Figure 3). However, the timing and intensity of rainfall is critical; flooding during harvest season can lead to reduced yields.
Southeast Asia is a large and fast-growing importer of grains and oilseeds. Indonesia is among the world's top three wheat importers, and the Philippines is among the top ten. Many Southeast Asian countries are net importers of corn (Figure 4). Malaysia and Vietnam import about 100% and 75% of their corn, respectively. Southeast Asia's wheat and corn supplies come mainly from Argentina and Brazil. Wheat is used for food and feed, and most of the corn is used for feed. A global supply shortage will increase meat prices in Southeast Asia. It will also affect food trade. For example, Vietnam is the world's third-largest seafood exporter, but more than half of it is farmed fish and shrimp, which depend on imported feed.
Wet Dry Wet
Figure 3: La Niña-induced net wet and dry areas around the world and when
Source: International Climate and Society Institute
La Niña typically brings above-average rainfall to parts of Southeast Asia, often benefiting agriculture, but there is no guarantee this will always occur. Climate change is altering the dynamics of ENSO, and it is not yet known how that will affect La Niña, and future El Niños. One thing is known: climate change may make weather more extreme as a result of La Niña, increasing the risk of flooding, especially in low-lying agricultural regions. If rainfall coincides with sensitive periods in the crop cycle, La Niña can also cause significant damage to mature crops and exacerbate pest and disease outbreaks.
Whether they benefit or harm, Southeast Asian countries should act proactively to mitigate risks and capture potential gains. Rather than just celebrating that reservoirs may be filled again, governments should help farmers recover quickly from last year's El Niño-related challenges, including through extension services and favorable credits for inputs, to ensure maximum benefits are realized if an event occurs. In addition, policymakers should prepare for possible higher meat prices and trade disruptions due to reduced grain harvests in La Niña-affected Latin American regions. In the long term, policymakers should also invest in improved research and development of climate-resilient crops to ensure the long-term sustainability and resilience of food in the region.
This article was first published on ISEAS – Yusof Ishak Institute’s blog site Fulcrum.
