5 Ways Heat Can Kill

5 Ways Heat Can Kill

By Yisih Chai 21 August, 2024

It’s hot, it’s bad & it’s here to stay, killer heat has arrived. It claims nearly half a million lives each year & it could get worse as our planet continues to warm. But how does heat kill? CWR’s Chai shares 5 ways

It’s hot, it’s bad and it’s here to stay, killer heat has arrived. This global challenge claims nearly half a million lives each year and in the US alone, heat contributed to 2,300 deaths last year – more than any other natural disaster in the country.

Killer heat has arrived… but how does heat kill?

Adding to the worry is that we’re in a year of record-breaking temperatures both in Asia and worldwide – last month marked the hottest July on record – so it looks like killer heat is here to stay. Moreover, we are on track for around a 3°C rise above preindustrial levels if climate action is not stepped up, which means even hotter temperatures. But how does heat kill? We share five ways below from deadly wildfires to our bodies being vulnerable to heat and not-climate ready infrastructure to diseases.

1. Wildfires: A Triple Threat

There have been massively destructive wildfires in recent times, like the wildfire in Hawaii last August that wiped out villages and like the one blazing now in Jasper, Canada. The threats from these are clear, fire and smoke can kill – in California, toxic particles from wildfire smoke caused >50k premature deaths between 2008 and 2018 – but there’s more, wildfires are actually a triple threat.

Wildfires are a triple threat – the fire & smoke, release planet warming emissions & destroy crucial carbon sinks

In addition to the above, wildfires release massive heat-trapping emissions – Canada’s fires last year alone spewed 3.28bn tonnes of carbon dioxide, nearly 4x the carbon emissions as airplanes do in a year. And then on top of this, they destroy carbon sinks (trees, vegetation etc.). Canada’s 2016 fires wiped out millions of acres of boreal forests, known to store more carbon than any other terrestrial ecosystems. Both contribute to global heating, which in turn contributes to killer heat, which can kill us.

And now climate change found responsible for increasing burned areas

And the outlook is not good. Despite measures to protect against wildfires like Park Canada’s national fire management program, wildfires continue and could get worse. Scientists have found that they have doubled in frequency and intensity over the past two decades. Plus, modelled analyses showed that climate change was responsible for increasing the burned areas by up to 40% in Canada and 50% in western Amazonia during 2023-2024 fire season. Get more on what we can expect with wildfires going forward and how climate change is impacting wildfires from Jed O. Kaplan, professor at the University of Calgary. Plus, don’t forget about the “zombie fires” that we’ve seen in the Arctic that are hiding underground and can reignite anytime in the spring or summer.

2. Your Body vs. The Heat

Our bodies are vulnerable to heat and work hard to keep cool, especially on hot days. One way it does this is by sweating – when sweat dries, it carries heat away from your body’s surface and lowers your temperature. However, without enough water to replace those lost fluids, one risks dehydration that can overwhelm the body’s cooling system, leading to heat exhaustion or even deadly heat strokes. Just look at the recent Hajj pilgrimage in Mecca in June this year where more than 1,300 people lost their lives as temperatures soared to 51.8°C – the Saudi health minister said there had been attempts to warn the public of the dangers of extreme heat.

Our bodies are vulnerable to the heat…

….>1300 lost their lives in this year’s Hajj pilgrimage when temps soared to 51.8°C

Some of us are even more vulnerable so be alert! Kids under 4 and adults over 65 take longer to adapt to high temperatures and if you’re on certain medications or have any pre-existing conditions e.g. respiratory and cardiovascular illnesses, you might have more severe symptoms or your illness might worsen.

Plus the “wet bulb” effect, where heat and humidity combine, makes it even worse. In Singapore, there’s a network of Wet Bulb Globe Temperature (WBGT) sensors across the island to monitor heat stress levels, helping residents decide whether to limit outdoor activities or work.

3. Intense heat & bone-dry conditions: A Deadly Mix

Heat and drought are closely linked and often intensify one another in a vicious cycle. When we experience prolonged high temperatures, or heatwaves, they can trigger drought conditions by speeding up evaporation and drying out the soil. This rapid evaporation drains water supplies faster than rain can refill them, which means we end up with even longer stretches of dry weather and scorching temperatures.

Though droughts = only 15% of natural disasters, have claimed ~650k lives from 1970-2019…

…rapid evaporation adds strain on crucial water resources

Even though droughts only make up 15% of natural disasters, they have claimed ~650,000 lives between 1970 – 2019. Moreover, droughts are making things worse for the over 2bn people struggling with access to clean and safe drinking water by speeding up water evaporation.

Take the Mekong River Delta for example, also known as Vietnam’s rice bowl. In April 2024, it faced a severe drought due to El Niño, which reduced water levels in the river. The lack of water killed crops, raising concerns over food security. Additionally, saltwater crept 5-7km upstream because of the reduced flow, which contaminated the water affecting over 73k families.

4. Not Climate-Ready Infrastructure making us vulnerable

Our infrastructure is unprepared for climate hazards today including killer heat. Firstly, heat is creeping into the roads and buildings causing asphalt to soften, concrete to crack and metal to warp – not a comforting thought.

Heat is creeping into roads & buildings causing asphalt to soften + more

Power grids and the related infrastructure is also highly exposed to heat. Already there have been cases where grids have overheated due to high temperatures as well as due to increased demand – linked to the use of cooling equipment; which FYI while it’s cooling you down it’s actually heating the planet up – that leads to blackouts. These blackouts can force businesses to shut down, roads become dangerous when traffic lights fail and it can also be life-threatening, with hospitals forced to run on generators.

We must rethink disaster management and infrastructure planning. For example, we are unprepared for sporadic heavy downpours we have now due to the changing climate. Even our soft infrastructure like information systems need upgrading too – Covid-19 exposed this. Climate extremes will only worsen, and our infrastructure must be ready.

5. Pathogenic Diseases: Thriving as Temperatures Rise

This way that heat kills is something you might not have thought about… Rising temperatures turn freshwater bodies into perfect breeding grounds for bacteria and parasites, spreading diseases like cholera and typhoid fever. It turns out that 58% of infectious diseases have gotten worse at some point by climatic hazards sensitive to GHG emissions and warming is the biggest culprit.

58% of infectious diseases gotten worse by climatic hazards

Global warming is also expected to cause a huge increase in mosquito-borne diseases like dengue and chikungunya, even spreading to previously unaffected areas like Europe and the US.

In places with limited access to clean water and sanitation, the risk is even higher – between 2010 and 2021, 97% of cholera cases were from 31 of the 34 countries with the lowest levels of water and sanitation services.

 Heat also comes with social & economical impacts – forced migration >216mn by 2050 + “heatflation”…

…urgently need to cut emissions & solid heat action plans

It’s not just about feeling hot and sweaty anymore – if you’re curious about the bigger picture, dive into this interactive infographic. Jack Marley, an Environment & Energy Editor at The Conversation also tells us more on how these diseases could only spread more and potentially lead to new ones emerging. Remember, if Earth gets sick, so do you.

As you can see, heat kills in many ways but it also comes with social and economic impacts like “heatflation“, which is due to resource shortages. And by 2050, 216 million people might need to move to escape extreme heat – that’s comparable to the entire population of Brazil. Even cold places like Antarctica and Greenland aren’t spared and experiencing rapid ice melt; living in Singapore, the idea of sea levels rising too fast too soon from this ice melt is nerve-wracking. It’s time for rapid and deep emissions cuts and solid heat action plans.

Further readings

• Hot, Thirsty, Sweaty & Wet: HK’s Future Down The Drain? — CWR’s Chan & Tan look beyond current tensions & see very real threats to HK’s future from climate change
• Rising Temperatures, Melting Ratings – 63 countries will suffer climate-induced rating downgrades in the world’s first climate smart sovereign rating simulation. More key findings from Dr Klusak, Dr Agarwala, Burke, Dr Mohaddes & Dr Kraemer
• Heat Waves Hit the Poor Hardest – Heatwaves are among the deadliest disasters and poorer countries will be 2-5x more exposed to them by 2060, which risks $ billions. Sadegh, Abatzoglou & Alizadeh share more key findings from their research

More on Latest

• A Conversation with Jed O. Kaplan – Climate Change & Wildfires – Wildfires are raging like never before. What’s supercharging them? We sit down with Kaplan, Professor at the University of Calgary, to find out the key ingredients, the impacts climate change is having & what can be done
• If Earth gets sick, so do you – Earth’s growing fever has repercussions for human health. What should we be worried about? How is climate change changing the transmission of >20 tropical diseases? Are our brains at risk? Marley from The Conversation covers these questions and more
• Cooling Equipment: Keeping Us Cool but Heating Up the Planet – Ever think about the hidden costs of blasting your AC? Turns out it’s worse than just soaring energy bills. CWR’s Lam unpacks why our cooling habits could be warming our planet faster