Repeat of 2015 haze crisis unlikely: Experts

SINGAPORE – Since August, countries in South-east Asia, including Indonesia and Malaysia, have been choking in a blanket of persistent haze caused by raging fires in Indonesia.

Dense smoke haze has been seen over southern and central Sumatra and various parts of Kalimantan on most days since Aug 21.

Forest fires in Indonesia are more easily sparked during the ongoing dry season, which usually stretches from June to October. In 2026, the fire season is further worsened by a “Godzilla” El Nino phenomenon, which makes the weather hotter and drier.

The confluence of these events has conjured flashbacks of the region’s worst air pollution incident in 2015. That year was also an El Nino year, and the fires caused the Pollutant Standards Index (PSI) – a measure of air quality in Singapore – to soar above 300 in September, reaching hazardous levels and forcing schools to shut for a day. Half a million cases of respiratory infection were recorded in Indonesia then.

But weather experts told The Straits Times that a repeat of such a disaster in 2026 seems unlikely, mainly because the onset of El Nino happened around June, later than the April onset in 2015. This means that the effects of 2026’s El Nino will have a shorter overlap with the traditional dry season.

However, the severity of haze pollution experienced here can also be affected by other factors.

The Straits Times speaks to weather and forestry experts on how the haze forecasts for the region could shape up.

What leads to haze over Singapore?

The severity of haze and when it occurs depend on the duration of dry weather, wind conditions and direction relative to the location of fires, the extent of burning, as well as measures taken on the ground to suppress fires, said the National Environment Agency (NEA).

During the current dry south-west monsoon season, winds are expected to blow from the south. Smoke plumes from southern Sumatra and the southern parts of Kalimantan could be transported towards Singapore if the fires intensify, said NEA.

Other weather events, such as typhoons near Singapore, could also contribute to the appearance of haze over the Republic, said Wang Jingyu, a weather expert and assistant professor at the National Institute of Education.

For instance, two typhoons brewing near the northern part of South-east Asia on Aug 24, when the PSI in central Singapore neared the unhealthy range of 101 and above, could have contributed to the hazy conditions over Singapore that day, said Wang.

He explained: “The two typhoons, Narra and Saudel, developed over the north-east of South-east Asia. These systems concentrated moisture around themselves, making South-east Asia even drier on top of the existing dry conditions already worsened by El Nino.”

The typhoons also strengthened winds from the south and promoted the movement of transboundary haze towards Singapore, he added.

The PSI in the central region inched up to 99 before dropping.

Since then, the PSI has dropped to the moderate range.

How does 2026’s El Nino affect haze forecasts?

While both 2015 and 2026 are super El Nino years, the NEA and weather experts do not think that the 2026 forest fires will match the extent of those in 2015.

This is because the current El Nino started later than the 2015 cycle. The El Nino in 2015 had an onset in April, and a long impact on the dry season, said NEA.

“Extensive fires and dense haze were observed across the region, resulting in prolonged periods of air quality registering ‘Unhealthy’ or worse over Singapore,” said a spokesperson.

In comparison, the 2026 El Nino started later around June, and the number of hot spots over Sumatra and Kalimantan so far is lower than in 2015.

NEA noted that there could still be periods of haze, especially during prolonged dry spells. 

“The severity and duration of haze episodes will depend on how the ground situation subsequently develops and the extent of fires,” said the agency.

According to the Indonesian government’s forest fire monitoring system, more than 202,000ha of forest and land had been burned by the end of July 2026.

In comparison, the 2015 inferno charred about 2.6 million ha of land during the fire season.

Koh Tieh Yong, adjunct associate professor in meteorology and climate science at NUS, stressed that transboundary haze is at its core a man-made disaster sparked by using fire to clear land for agriculture.

If hot-spot detection, fire-fighting efforts and enforcement achieve their objectives, “we may still avert the worst impacts this year compared to 2015”, he said.

What is causing the widespread fires in Indonesia?

Fire is widely used as a cheaper option for agricultural land clearing by both smallholders and plantation companies, as burning costs far less than machines, said Dede Sulaeman, research lead for peatland monitoring at the World Resources Institute (WRI) Indonesia.

Many of the hot spots are seen on plantation land, called concessions, he added. “Concessions represent land with full control by companies, which should play a significant role in preventing fires and achieving a zero-fire target,” said Dede.

His colleague Muslih Biladi, a land use and supply chain analyst, added: “Many companies still struggle to keep fires from breaking out, and even large firms continue to see hot spots turn up in their subsidiaries’ concessions or in supplier areas near their production sites.”

Agricultural land in Sumatra and Kalimantan has been a tinderbox for decades since waterlogged peatlands were drained for plantations, making the land dry and flammable.

El Nino just amplifies the human-caused burning. “The risk is therefore highest when human activities occur in already degraded or drained landscapes and coincide with prolonged drought,” Dede said.

Wahyu Perdana, advocacy, campaign and communication manager of non-governmental organisation Pantau Gambut, noted that since 2015, the government has made important improvements in early warning, firefighting capacity and fire-prevention efforts.

“However, the persistent challenge is that responses remain too often reactive, sporadic and incident-based, whereas peatland fire management requires structural and preventive intervention,” he added.

In end-August, the Indonesian authorities arrested 89 people suspected of starting forest and peatland fires.

Dede added: “Although law enforcement efforts have been strengthened, challenges remain in establishing the causes and chain of responsibility for forest and land fires.”

The budget allocated to firefighting has also shrunk in 2026. While the Indonesian government has set aside 5 trillion rupiah (S$358 million) in reserve funds for disaster response, firefighting will need to contend with competing needs, including the recent major earthquake in East Nusa Tenggara, he noted.

What affects the strength of an El Nino?

An El Nino is declared when the temperatures of the sea surface in the central and eastern Pacific Ocean – roughly between Australia and South America – warms by at least 0.5 deg C above the norm.

A strong El Nino happens when the warming is at least 1.5 deg C. A super, or “Godzilla”, El Nino happens when the sea surface warms 2 deg C and above.

According to the Australian meteorology bureau, the sea surface temperature in this El Nino monitoring region has risen by 2.45 deg C. It added that the current warming of the central equatorial Pacific is forecast to reach levels above the warmest seen since proper records began in 1950.

Koh said El Nino develops because of an instability in the interaction between the tropical Pacific Ocean and the atmosphere. How strong these unstable disturbances grow is random.

“But the stronger they are, the more rarely they occur. We have had very strong El Ninos once every 10 to 20 years since instrumental records began. The current occurrence seems to follow this pattern,” he added.

A new study tracing El Ninos of the past 900 years – published in scientific journal Science in August – has shown that the phenomenon has been exacerbated by climate change.