Southeast Asia braces for more droughts, haze

Malaysia and the rest of Southeast Asia face heightened risks of haze, drought, and water shortages with El Niño being declared this year.

The onset of dry conditions can typically last a year beginning in either July or August. The region was last hit by El Niño in 2015 and 2016 when several countries were blanketed by a transboundary haze that resulted in canceled flights and classes, a sharp increase in respiratory ailments, and deaths. Water rationing was also introduced due to drought.

The United States National Oceanic and Atmospheric Administration agency says that El Niño will strengthen toward the end of 2023, with a 56 percent chance of it peaking as a strong event, and an 84 percent likelihood of it being a moderate event.

A strong El Niño could impact Sumatra, Java Island, Sulawesi, and southern Borneo with drier conditions from September to November, while northern Borneo and the southern Philippines could experience dry spells from December to February.

Extensive open burning or forest fires in Sumatra and Kalimantan could mean a transboundary haze when the southwest monsoon sweeps the particles toward Singapore and Malaysia.

The 1997-1998 El Niño event is an example of an El Niño-induced drought and transboundary haze disaster, which was considered the most severe in Southeast Asia, lasting three months and causing billions of dollars in losses from disrupted air travel and businesses, plus increased health-care expenditures.

It also caused droughts and flooding in other parts of the world, with extreme rainfall in Africa and North America and one of Indonesia’s worst droughts on record. The year 1998 ultimately became one of the warmest years on record.

The El Niño and La Niña weather patterns result from complex interactions between the atmosphere and the ocean, with significant warming or cooling occurring in the eastern tropical Pacific Ocean. These interactions disturb air flows in the lower atmosphere and lead to localized air-sea interactions that impact weather across the globe.

The drier-than-normal conditions are influenced by two anticyclonic systems active over the southern Indian Ocean and the northwestern Pacific Ocean. These systems act as controlling mechanisms, shaping the movement and intensity of dry conditions across regions.

While air-sea interactions shape the local impacts of El Niño, monsoon winds also help, strengthening it during the summer months (June to August) and weakening it during winter (December to February). In the summer months in Southeast Asia, southerly winds prevail, blowing northward from Kalimantan and Sumatra.

These winds enhance the southwesterly monsoon winds which can blow the smoke haze from Sumatra and Kalimantan toward Singapore, Peninsular Malaysia, Sarawak, Brunei, and Sabah. During autumn (September to November), the southern part of Southeast Asia (Sumatra and Kalimantan) continues to experience reduced rainfall, while conditions in Peninsular Malaysia return to normal. However, in Borneo, the area of reduced rainfall expands northwards, covering the entire island.

This dry weather aids the outbreak of large-scale forest fires in southern Sumatra and Kalimantan which result in the haze. Southeast Asia’s geographical location between the Pacific Ocean and the Indian Ocean exposes the region to the influence of both El Niño in the Pacific and the Indian Ocean dipole occurrence.

The dipole is a climate pattern characterized by temperature differences between the western and eastern parts of the Indian Ocean. Similar to El Niño, it affects air-sea weather patterns and ruffles the southern part of Southeast Asia.

If these two climate phenomena occur together, they can bring out the worst in each other, causing disaster-scale droughts and haze especially during the summer and autumn seasons. The various phases of an El Niño phenomenon, spanning its origin to its influence on regional atmospheric and oceanic processes, is a complex interplay between anticyclonic circulations, monsoon winds, sea surface temperatures, and other atmospheric variables. These interactions collectively shape the drier-than-normal conditions over Southeast Asia during El Niño events.

Gaining a comprehensive understanding of these dynamics is essential to accurately predict and manage the impacts of El Niño on our climate and associated socioeconomic sectors. To mitigate the effects of haze episodes, proactive measures including monitoring and controlling human activities that contribute to fire outbreaks are important to ensure the well-being and sustainability of affected regions. The Jakarta Post/Asia News Network

——————

Ester Salimun, Ph.D. is a senior lecturer at the Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan, Malaysia. This was originally published under Creative Commons by 360info.

——————

The Philippine Daily Inquirer is a member of the Asia News Network, an alliance of 22 media titles in the region.