Written by: Yao Hua Law

El Nino reliably warms up Malaysia but its impact on rainfall is more nuanced and spotty. Still, as global warming drives more extreme weather events, experts foresee El Niño causing more droughts too.

LAST MONTH must have felt like a furnace for many people across the world. Hundreds of millions suffered heatwaves in India, Europe and the United States. Dozens died. Since 1850, humans have waged world wars and landed rovers on Mars, but we have never stifled in a warmer month than July 2023.

July also marked the return of a natural climate phenomenon called El Niño. Last observed in 2019, El Niño tends to lead to warmer and drier months in tropical Asia. Scientists expect this El Niño to last through March 2024.

(Photo: At its Weather Operation Centre in Selangor, the Malaysian Meteorological Department constantly monitors the country’s weather using satellite and radar data. | Pic by YH Law)

While Malaysia has not declared any extreme weather events this year, authorities are concerned. Since June, the dry weather has prompted government agencies to conduct cloud-seeding to replenish dams. Many Malaysians would recall the severe heatwaves and months-long droughts that hit the country during strong El Niño episodes in 1997/1998 and 2015/2016.

And El Niño is more likely to cause drastic impacts now than before. That is because Malaysia is warmer than in the 1990s, partially due to human-caused climate change. Experts say the extra heat injected into the seas, winds, and clouds would fuel extreme weather. The risk escalates as the world warms.

“If I may make a bold conjecture,” says climatologist Liew Ju Neng of Universiti Kebangsaan Malaysia, “I would say that the El Niño effect will be more widespread.”

El Niño is a complex process that keeps upturning expectations. For example, at times, El Niño events have increased rather than reduced rainfall in Malaysia. To see what lies in store for Malaysia’s climate, we looked to the past for telltale signs.

Historical records show that El Niño exacerbated heat, but Malaysia has been warming up even without El Niño. Effects on rainfall patterns were less straightforward, but predictions point to more droughts and floods in the country.

El Niño heats up Malaysia

There is no doubt that El Niño turns up the heat in Malaysia. Weather data from the Malaysian Meteorological Department shows that the top three maximum daily temperatures were recorded in years of strong El Niño. These were April 9 1998, April 10 2016, and March 27 1998 with readings of 40.1°C, 39.3°C, and 39.1°C, respectively.

separate study in 2021 also concluded that El Niño had a “considerable effect on the warming in Malaysia” between 1985–2018.

Very high temperatures are deadly. Prolonged exposure can kill, particularly when humidity is high and our sweat cannot evaporate to cool our bodies. The Malaysian Meteorological Department declares a hot weather alert when maximum temperatures exceed 35°C for 3 days in a row. In years with El Niño events – even weak ones – such dangerously hot days were more common.

Between 1985 and 2022, El Niño caused the number of potential hot weather alert days (above 35°C) to double in 6 cities. These cities have complete weather data that can approximate the conditions across Peninsular Malaysia. While this year’s El Niño has only just begun and remains weak, worrying signs are emerging. By the end of June, there were already 47 days that were warmer than 35°C in Alor Setar, Subang, Melaka, Kluang, Kuantan, and Kota Bharu.

The extra heat brought by El Niño is worrying enough. But there are also climate change and global warming which are caused by human activities. What can we expect when they come together?

In actual fact, Malaysia has been warming, even without El Niño. This is according to weather data compiled by the World Bank Group and University of East Anglia. The Malaysian Meteorological Department corroborated this trend with Macaranga.

Before 2000, 8 of Malaysia’s 10 hottest years coincided with El Niño; after 2000, El Niño featured in only 4 of the 10 hottest years. In fact, 9 of Malaysia’s 10 hottest years since 1950 came after 2000. This suggests that Malaysians are more and more experiencing sweltering temperatures even without the searing force of El Niño.

Alarmingly, this would also suggest that we can expect worse when El Niño enters the picture.

Variable El Niño impact on rainfall

El Niño is also often thought to reduce rainfall in Southeast Asia. But while it increased temperatures across Malaysia, its impact on rainfall is more spotty and variable.

Some studies reported that El Niño years were reliably drier in Southeast Asia and Peninsular Malaysia for the periods of 1960–2018 and 1989–2018, respectively. In the Peninsular Malaysia study, the authors found that El Niño reduced rainfall in Kedah and Terengganu more than in other states.

On the other hand, the Malaysian Meteorological Department told Macaranga that they did not detect any significant impact of El Niño on yearly rainfall patterns in Malaysia. They had examined country-wide data for 1951–2022.

Macaranga had also looked at bouts of continuous dry days in Peninsular Malaysia. Here too there was no obvious impact of El Niño. Years without El Niño also had long stretches of dry days.

Although the analyses do not fully agree, they share some findings. Generally, El Niño events reduced rainfall in northern Sabah and northern Peninsular Malaysia, but less so in Johor, says climatologist Liew Ju Neng. That restricted impact however, would expand to other areas during a strong El Niño event, such as that in 1997/1998.

Even less clear is the combined impact of El Niño and human-caused global warming on rainfall. The Malaysian Meteorological Department sees no relationship between rainfall patterns in Malaysia and global warming. Likewise, an independent 2022 study found that while heavy rainstorms have increased across Peninsular Malaysia except in Johor since 1989, these changes do not correlate with global warming.

Moisture all around

Malaysia’s geography might explain why its rainfall has been less influenced by global processes like El Niño and global warming. The seas around the country provide plenty of moisture to form rain clouds even during El Niño, says Ambun Dindang, senior director of the Meteorology Instrumentation and Atmospheric Science Center at the Malaysian Meteorological Department.

The authors of the 2022 study also noted that the formation of these clouds happens on small local scales that might not be readily changed by bigger processes.

While historical rainfall records do not present a simple picture, scientists have produced clearer predictions of what is to come.

Many climate models predict that global warming will lead to more extreme weather. That would mean that droughts would become more severe and frequent, but so would floods.

“The climate is always fluctuating between dry and wet,” says Liew. More energy in the system will drive higher rates of fluctuation, and therefore higher chances of heavy rains and droughts.

Droughts more likely

In a 2017 study, Liew’s team simulated rainfall patterns under various future carbon emissions and socio-economic scenarios. In most cases, Malaysia will experience less rain in December to February, and more rain in June to November.

“The risk of drought will get higher. We are talking about an increment of 15–30%,” says Liew. “We have seen numbers higher than 30%, but this is based on modelling and I would rather be more conservative about the numbers.”

Some of his other models also predict that in a warming world, areas that have been relatively unaffected by El Niño, such as Johor, would not be spared.

“Crazy stuff” is coming

El Niño, and the larger ENSO phenomenon of which it is a part, are some of the most complex climate processes. Many scientists acknowledge that we have yet to fully understand them, not to mention conclude how they might change in a warming world. “No two ENSO events are the same,” wrote one highly cited 2021 study that reviewed ENSO models.

But consensus is emerging. The same study found that the most accurate models also tended to predict that climate change would lead to more intense ENSO events. Perhaps such findings are best summed up in a citation in a 2019 review paper. “From now on every El Niño event is going to generate all these weird extremes,” said the El Niño researcher. “We have to be ready for the crazy stuff.”

[Edited by SL Wong]

We thank the Malaysian Meteorological Department for supporting data journalism and providing us with weather data.

Correction: Aug 9:  We have corrected our mistake that said that the Malaysian Meteorological Department declares a heatwave when temperatures stay above 35°C 3 days in a rowit should be a ‘hot day alert’ instead.

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