Last year, I wrote about the world reaching its first climate tipping point: waters in tropical seas have warmed 1.5 degrees Celsius above pre-industrial levels and are causing massive die-off of coral reefs [https://www.bernama.com/en/news.php?id=2479881].
This is a sobering thought as without coral reefs, home to thousands of marine life, the collapse of one ecosystem will set off a cascade that ends with us hungry or worse. If the seas are no longer hospitable to the corals, it stands to reason that humans are headed the same way unless we manage to cool down the Earth enough.
My trip to Pulau Sibu, Johor, earlier this month drove home the point.
I was there on a media familiarisation trip to the island, which is smack dab in the middle of a marine park where Malaysia’s elusive dugong (dugong dugon) population likes to visit and play. The trip was organised by the Habitat Foundation and MareCet, a group dedicated to the research and conservation of marine mammals in Malaysia.
I did not get to see any dugong, unfortunately, other than the few ripples I got to see when one of them stuck its head out, only to hightail out of there when an excited conservationist spotted it and bellowed for the marine biologist diving nearby.
What I did get was a crash course in the consequences of living in a rapidly warming world.
DUGONG SEARCH MEETS WET BULB
It was about 11 am and the sun was intense. There were a few storm clouds, but they were far away.
The sea was calm with little wind, which MareCet co-founder and marine biologist Dr Louisa Ponnampalam said were ideal conditions to spot a dugong. Not because they like calm seas but because “it’s easier to see them when they break the surface”.
A few of us had gone into the water, about three or four metres deep and with plenty of sea grass, the dugong’s favourite food, on the sea floor. According to Dr Louisa, there are about 100 dugong left in Malaysian waters. They are endangered in Malaysia due to the degradation of sea grass and their vulnerability to fishing activities. These marine mammals are listed as Vulnerable to Extinction on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.
The Mersing Archipelago in Johor, which includes Pulau Besar, Pulau Sibu and Pulau Tinggi, is one of the major spots for dugong.
It was hot on the boat and despite the blinding sun, it was humid. I had started to feel a little nauseous and dizzy. Malaysia had issued some heat advisories, albeit not in Johor. The high temperature for the day on Pulau Sibu was 32°C, while several areas in northern Peninsular Malaysia recorded highs above 35°C.
After an hour or so, we made our way to Pulau Sibu Kukus, where we had a picnic lunch. Despite drinking isotonic drinks, staying in the shade and limiting my physical activity, my situation did not improve much. I had gone wading in the water for a bit, which helped cool me down a little, but that did not last.
We started hearing thunderclaps and seeing lightning strikes over the islands on the horizon, but did not think the storm would affect us until it did. Then it was a rush to pack everything up and get everyone into the boat before the storm hit.
We managed to outrun the storm when we got back to Pulau Sibu. But rain was just a matter of time. It was humid – a Google search pegged humidity at 85 percent. Rather than shower, I chose to take a nap, hoping to get over my exhaustion. It was the wrong move.
A few hours later, I was bent over in the middle of the dung-covered field, emptying the contents of my stomach while on a walkabout in the village on the island.
I knew then it was due to heat exhaustion and it was serious. Despite sweating and drinking isotonic beverages, I had hit my ‘wet bulb temperature’ limit.
WHAT IS WET BULB?
Wet bulb temperature (WBT) takes into account the dry temperature, which is the temperature outside under the shade, and humidity, and calculates the coolest and lowest temperature the human body can reach via sweating in these conditions. Wet Bulb Globe Temperature (WBGT) is the next step, taking WBT and combining it with wind speed and solar radiation. These measurements have been gaining popularity as a more accurate way to predict heat stress.
While Malaysia uses WBGT, it also uses Heat Index, which combines air temperature and relative humidity for a “feels like” temperature reading, to warn the public.
The human body cools itself by sweating. When sweat evaporates, it takes away the heat within. But when the conditions outside no longer allow for sweat to evaporate, that is the WBT limit. The theoretical lethal WBT limit for humans is 35°C, although research by Pennsylvania State University in the United States on young healthy adults in 2022 found that high humidity lowered the limit to 30 to 31°C.
National University of Singapore Heat Resilience and Performance Centre director Dr Jason Lee told me that, given the dry temperature and humidity on that day, my WBT was about 29.9°C.
“(W)hen the wet bulb temperature is high, it means there's a lot of water vapour in the atmosphere. It doesn't mean you still cannot evaporate your sweat. Some of the sweat can still be evaporated. So what I'm saying is that most of it cannot be evaporated and therefore you build heat very fast,” he said.
The irony is that my body warned me I was on the road to a heat stroke even before we left for Pulau Sibu Kukus. I had noticed droplets of water on my arm during breakfast. Like I had been swimming or just taken a shower. But it was all sweat. The tell-tale sign was that the droplets were not evaporating.
Although I had stayed hydrated, Lee warned that drinking alone was not enough to stave off heat exhaustion or heat stroke, either.
“(H)ydration is important, but through the course of my work, (I found that) many assume that all they need to do is to hydrate more to beat the heat, but that is insufficient. You should still continue to drink because you will continue to sweat, but that cannot be your only strategy.”
I was curious why I was so badly affected while others in my group were not. All of us were exposed to the same amount of sun, and some even more than me. The crucial clue was the fact that I did not go swimming during the excursion or take a shower upon returning. While immersing myself in cool water would have helped reduce my core body temperature – “Once you are in the water, it's actually 24 times more powerful than in the air,” Lee commented – my reasoning was that I felt so exhausted I just wanted to rest and do nothing.
Lee understood, saying this is an issue with the warming world where people would adjust their behaviour to avoid heat, such as staying indoors in air-conditioned rooms, to the detriment of their health in the long-term.
BECOMING UNINHABITABLE
Southeast Asia is experiencing and will continue to experience extreme heat events, according to research. For example, Houmsi et al reported in their paper ‘Spatiotemporal Changes in Hourly Wet Bulb Globe Temperature in Peninsular Malaysia’ – published in 2023 in the Switzerland-based MDPI Sustainability journal – that the WBGT had increased over the decades to 30.5°C in the western coastal region.
To make matters worse, a Super El Nino is expected to occur between mid-year to early next year. In Malaysia, it means severe droughts, record-breaking heat and haze. As of March 31, health authorities in Malaysia reported one death and 15 heat-related illnesses.
Other than increasing green cover and cutting carbon emissions to help reduce the effects of climate change and global warming, Lee, who is also the chairman of WHO-World Meteorological Global Heat Health Information Network Southeast Asia Hub, said for the time being, there are steps the public can take to prevent and reduce heat stress.
“(With the) four environmental stressors, if you cannot affect dry heat and humidity, you can still affect solar radiation and the wind,” he said.
He said the best way to stave off heat stress is regular exercise to help the body acclimatise as well as recognise the warning signs and take the necessary steps. He added that going outdoors is still beneficial for one’s physical and mental health in the long run, as long as people are careful.
He suggested carrying a portable fan, being in the shade and reducing UV exposure.
“The problem is for us who are living in a perpetually warm and humid environment like Southeast Asia and living in a city. The problem we face is not one of heat stroke because we have enough cooling facilities to avoid the heat.
“And therefore, the bigger question for us is, while we might not see many cases of heat stroke, we are seeing our whole population not living to their true potential because we avoid the heat as much as possible,” he said.
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