We Need To Talk About Deadly Heat

Simon Kerr
4 min readNov 8, 2021

Everything with the climate dilemma is moving much faster than anticipated…

(David Law, Unsplash)

… including super deadly heat waves.

In July 2021, an off-the-charts heatwave hit the upper western seaboard of the US and Canada, including the 49.6°C heat smashing record in the now devastated town of Lytton in inland British Columbia. This is another wakeup call of the realities of climate disruption. Before that Sunday in early July, temperatures had never risen beyond 45°C in Canada.

This is a 5°C jump in heat. Unprecedented is an understatement.

For the record, Scientists have determined that this extreme heat was virtually impossible without climate change.

As the world heats up, it will produce increasingly deadly heat events, both for humans and non-humans. This is now an unavoidable future for many parts of the world, including Australia. These weather extremes and climate feedback loops are what scare scientists. It is what we ought to expect with a world that is getting hotter.

Absolute temperature is not the only dangerous part of a heatwave. I have cycled the 12km from work in 44°C days in Melbourne where I live. Maybe not the brightest thing to do, though I was fit, well hydrated and humidity was low. I was also close to the limit of my tolerance.

The other aspect of deadly heat perhaps poses the most danger. This comes from the wet-bulb temperature, which measures not just absolute temperature but also humidity. It is something we need to know about.

Our internal body temperature is around 37°C. We can avoid overheating in temperatures above this if we can still sweat (though only for a limited time and depending on our health and fitness). In arid, low humidity environments, such as my bike riding example above, we can tolerate temperatures above our body’s 37°C. But once the humidity (the amount of moisture in the air) reaches a certain point, sweating will no longer cool us.

Here is the kicker: even when the air temperature is a little lower than our internal body temperature, if this is combined with high humidity, then we are physiologically in trouble. Our usually highly reliable internal cooling system gets overwhelmed, and we can’t shed the internal heat that builds up in our body.

Unless we can escape prolonged exposure to these dangerous wet-bulb temperatures we will die. Science fiction writer, Kim Stanley Robinson, details this in graphic detail in the beginning of his recent novel, The Ministry for the Future. Heatwaves will not feel so safe after reading the first chapter. It is, frankly, terrifying.

For a really useful and more technical explanation of what the wet-bulb temperature is and why it is so dangerous read this short Medium article by Tim Anderson: Wet Bulb temperature is the scariest part of climate change that you’ve never heard about

Dangerous heat is already built into our future

Our planet is already committed to much more dangerous heating in the years and decades ahead. It is built into our future.

We need to talk about heat; about preparing for heat, about ensuring our cities can stay cool and our infrastructure can cope. We must plan ahead to ensure everyone has a safe place for extended heat waves. This is both an issue of technology and social justice. Those living in cheaper, poorly insulated housing without access to a cool safe place will bear an unfair burden on their health and, potentially, capacity to survive.

This may well mean air-conditioning, both for households and in public safe zones. This is another powerful reason to speed up transition to clean energy. We will need a lot of energy when these events strike. And it must not be powered by coal, one of the big reasons our planet is heating in the first place.

The burden on emergency services is already massive in heat waves. This will only increase and likely to exceed their capacity in peak demand. Building heat protection into urban planning is preventative.

But we must also give serious thought to how non-humans will cope, the wild creatures as well as those in our care, including farm animals. As Humans drive up planetary temperatures, safe spaces for many non-humans will decrease or disappear, and many already live near the limits of their tolerance.

We have much work to do.

Postscript: the climate and ecological crises need not be the end of our world

We must adapt to this new eaarth. There are real limits in our capacity to adapt and no guarantee we will, or can. Yet, at this point, the climate and ecological crises need not be the end of our world. But if we are to have any chance of a positive future, learning how to live with devastating climate disruption is now no longer an option. For anyone.

It is all hands to the plough for every citizen, parent, business owner, musician, investor, policy maker, artist, farmer, decision maker, educator, entertainer … it must enter the DNA of how we think and act from this point on-wards if we are to have a fighting chance of a liveable future.

And talking of a fighting chance, have a listen to the title track of our new (2021) climate-album, Only One Way To Head.



Simon Kerr

Climate change thinker, research fellow, creator of ‘Music for a Warming World’, www.musicforawarmingworld.org and has a PhD in Politcal Ecology