CNA Explains: Here’s why extreme weather has been plaguing Southeast Asia

Key Concepts

• La Niña: A climate pattern characterized by cooler-than-average sea surface temperatures in the central and eastern tropical Pacific Ocean, which influences global weather patterns, often leading to stronger monsoon rains in Southeast Asia.
• Negative Indian Ocean Dipole (IOD): An oceanic phenomenon where the western Indian Ocean becomes cooler than average and the eastern Indian Ocean (near Indonesia) becomes warmer than average, drawing moisture towards the warmer waters.
• Atmospheric Moisture Capacity: The ability of warmer air to hold more water vapor, leading to more intense rainfall during storms.
• Climate Change/Global Warming: The long-term shift in global weather patterns, primarily due to human activities, leading to rising global temperatures and more frequent extreme weather events.

Unprecedented Rainfall Events in Southeast Asia

Southeast Asia is currently experiencing a generation-defining period of extreme rainfall and flooding. Recent weeks have seen devastating impacts across the region:

• Southern Thailand: Entire towns have been submerged underwater.
• Central Vietnam: Recorded an astonishing 1.7 meters (1700 mm) of rain in a single day.
• Philippines: Hit by successive "super typhoons," forcing over 1.5 million people to evacuate their homes.

Collision of Climate Forces: The Primary Drivers

This severe weather is attributed to the rare simultaneous alignment of two major climate systems:

1. La Niña: This phenomenon cools the central Pacific Ocean and pushes heat westward. This shift intensifies monsoon rains across Southeast Asia, contributing significantly to increased precipitation.
2. Negative Indian Ocean Dipole (IOD): Characterized by warmer-than-usual waters near Indonesia. These warmer waters act like a "giant magnet," pulling in substantial amounts of moisture from the surrounding atmosphere.

The overlap of these two powerful climate forces has resulted in "supercharged rainfall," transforming an already challenging rainy season into a full-blown disaster.

The Role of Climate Change and Global Warming

Beyond the immediate climate patterns, global warming is significantly exacerbating these events, making them more intense and frequent:

• Warming Oceans and Atmosphere: As oceans warm, the atmosphere also warms.
• Increased Atmospheric Moisture Capacity: Warmer air has a greater capacity to hold moisture, akin to "adding a bigger sponge above us." This means that when storms form, they are capable of dropping significantly more water.
• Accelerated Regional Warming: Climate scientists report that Asia is heating up at twice the global average rate. Consequently, what were once considered "once in a century floods" are now occurring every few years, indicating a rapid shift in climate patterns.

Escalating Risks and Future Outlook

The region faces ongoing and escalating risks:

• Saturated Ground: The ground across Southeast Asia is already heavily saturated from previous rainfall. This condition means that even normal amounts of rain can now easily trigger dangerous landslides or fresh, widespread floods.
• Persistent La Niña: La Niña is projected to continue influencing weather patterns until 2026, suggesting that the heightened risk of extreme rainfall and associated disasters will persist for several more years.

Regional Adaptation Efforts and Challenges

Governments throughout Southeast Asia are actively attempting to adapt to these new climate realities:

• Infrastructure Upgrades: Efforts include upgrading drainage systems and constructing coastal defenses to mitigate flood impacts.
• Improved Forecasting: Investments are being made in enhancing weather forecasting capabilities to provide earlier warnings and better prepare communities.

However, scientists issue a stark warning: the impacts of climate change are escalating at a rate faster than the region's capacity to adapt. This suggests that current adaptation measures may be insufficient to keep pace with the rapidly changing climate.

Synthesis and Conclusion

The extreme weather events in Southeast Asia, driven by the rare convergence of La Niña and a negative Indian Ocean Dipole, are profoundly intensified by global warming. This situation represents a "preview of the new normal," with Asia's accelerated warming leading to more frequent and severe floods and related disasters. Despite governmental adaptation efforts, the scientific community warns that the rate of climate impact is outstripping the capacity for adaptation, positioning Southeast Asia on the front line of the global climate crisis. The persistence of La Niña into 2026 ensures that this elevated risk will continue, demanding urgent and scaled-up responses.