Sometimes you have the impression that the world is on fire.
Europe was boiling over in a heat wave dubbed setimana infernale - "hell week" - in Italy.
Temperatures exceeded 50 degrees Celsius in China and parts of America, where body bags filled with ice were used to cool hospital patients.
The hottest June of all time was recorded in Great Britain.
And in 2022, Great Britain recorded a temperature that exceeded 40 degrees Celsius for the first time.
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Last year, a heat wave caused 60.000 deaths across Europe.
No wonder the United Nations has warned that we are now living in an era of "global boiling".
"I think it's very important to understand that it's no longer something that's distant or far from us or something in the future. We're really feeling it now," says Professor Lizzie Kendon from the UK Met Office.
So what does a changing climate mean for our bodies and our health?
I usually turn into a puddle of sweat when it gets hot, but they invited me to take part in the heat wave experiment anyway.
Professor Damien Bailey from the University of South Wales wants to give me a typical encounter with a heat wave.
And so we'll start with 21 degrees Celsius, crank up the thermostat to 35 degrees and finally reach 40,3 - which equates to the hottest day in the UK.
"You will sweat and your body's physiology will change quite significantly," Professor Bailey warns me.
Professor Bailey ushers me into the weather chamber.
It's a room-sized piece of scientific equipment that can precisely control the temperature, humidity and oxygen levels of that hermetically sealed space.
I've been here once before to investigate the effects of the cold.
But the gleaming steel walls, heavy doors and tiny windows take on a whole new meaning in anticipation of the rising temperature.
I feel like I'm staring out of my own oven.
The temperature starts from a perfectly pleasant 21 degrees when the first instruction arrives from Professor Bailey to "take everything off".
In response to a raised eyebrow, he assures me that we'll find out how much I'm sweating by how much my weight changes.
After that, I'm strapped to a dizzying array of devices that monitor the temperature of my skin and internal organs, my heart and blood pressure.
A huge mouthpiece analyzes the air I exhale, and an ultrasound studies the blood flow to my brain via the carotid artery in my neck.
"Blood pressure is working fine, heart is beating fine, all the physiological signals at this point are telling me you're in great shape," Professor Bailey tells me.
We still have one quick brain test to complete - memorizing a list of thirty words - and then the ventilators start.
Temperatures are starting to rise.
My body has one simple goal - to keep the internal body temperature around my heart, lungs, liver and other organs at around 37 degrees Celsius.
"The thermostat in the brain, or the hypothalamus, is constantly checking the temperature and then sending out all these signals to try to maintain it," says Professor Bailey.
We pause at 35 degrees to take some measurements.
It's warm here now.
It's not uncomfortable - I'm just resting on the chair - but I'd hate to have to work or exercise in this temperature.
Some changes in my body are already obvious.
I look redder.
Damien too, he's stuck in here with me.
This is because the blood vessels near the surface of my skin open up to make it easier for my warm blood to release heat into the air.
Also, I'm sweating - I'm not dripping, but I'm noticeably glowing - and as the sweat evaporates, it cools me down.
Then we climb to 40.3 degrees and now I feel like the heat is killing me.
"It's not linear, it's exponential. "Five degrees Celsius doesn't sound like much anymore, but physiologically it's a much bigger challenge," says Professor Bailey.
I'm glad we're not climbing any higher than this.
When I wipe my forehead with my hand, it is soaked with sweat.
It's time to repeat the tests.
When I throw my sweaty clothes on the floor, towel myself off, and climb back on the scale, I'm shocked to discover that I've lost more than a third of a liter of water over the course of the experiment.
The cost of opening all those blood vessels near my skin to lose heat is also obvious.
My heart beats significantly faster and at 40 degrees it pumps a liter of blood per minute more through my body than when it was 21 degrees.
This extra strain on the heart is why there is an increase in deaths from heart attacks and strokes when temperatures skyrocket.
And as the blood enters my skin, my brain is at a loss.
Blood flow decreases and with it my short-term memory.
But the main goal of my body was achieved - keeping my internal body temperature at around 37 degrees.
"Your body does a nice job of trying to protect that internal temperature, but of course the numbers show you're not the same beast at 40 degrees as you were at 21, and that happened in less than an hour," says Professor Bailey.
In addition to the heat, this summer also brought strong storms in the Balkans:
Humidity factor
In my experiment, only the temperature changed, but another key factor that must be taken into consideration is the amount of water evaporation in the air - the so-called. humidity.
If you've ever been really uncomfortable on a steamy night then you can blame it on the humidity as it hampers our body's ability to cool down.
Sweating by itself is not enough - only when the sweat evaporates into the air does it have a cooling effect.
When there is already a high level of water in the air, it is more difficult for sweat to evaporate.
Damien kept the humidity at 50 percent (not unusual for the UK), but a team from Pennsylvania State University in the US tested a bunch of healthy young adults at different combinations of temperature and humidity.
They were looking for the moment when the internal body temperature starts to rise rapidly.
“That's when it gets dangerous. Our internal temperature starts to rise and this can lead to organ failure," says researcher Rachel Cottle.
And that point of danger is reached at lower temperatures when the humidity is very high.
The prevailing concern is that not only are heat waves more frequent, longer and more intense, but also wetter, says Kotl.
She points out that last year India and Pakistan were hit by a severe heat wave with simultaneously high temperatures and high humidity.
"It's definitely a 'now' problem, not a future problem," she says.
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The human body is designed to function at an internal temperature of around 37 degrees.
We start to feel dizzy and prone to fainting as the internal temperature rises closer to 40 degrees Celsius.
High internal temperatures damage our body tissue, such as the heart muscle and brain.
Eventually it becomes deadly.
"Once the core temperature gets up to about 41-42 degrees Celsius we start to see really, really big problems and if they don't get help, the individual will actually end up dying of hyperthermia," says Bailey.
This phenomenon - heatstroke - is considered a medical crisis.
People's ability to cope with heat varies, but age and ill health make us more vulnerable, and temperatures we once enjoyed on holiday can become dangerous at different stages of life.
"You'll walk out of the lab today with a smile on your face - all these statistics we're getting tell me you're up to the task and you've done an exemplary job," says Professor Bailey.
But old age, heart disease, lung disease, dementia and some medications can cause the body to already work harder to function and is less able to respond to heat.
"Every day is a new physiological challenge for him, and now when you add to it all the additional unpleasant heat and humidity, sometimes he can't defend himself from the challenge," says the professor.
How to cope?
Many of the tips for coping with the heat are obvious and well-known - stay cool, wear baggy clothes, avoid alcohol, cool the house, don't exercise during the hottest part of the day and stay hydrated (you saw how much I sweated in just an hour).
"The second tip is to try not to burn in the sun. A mild sunburn can throw off your ability to thermoregulate or sweat in as little as two weeks," says Bailey.
But dealing with the heat is something we may all have to get used to.
Without action on climate change, Professor Lizzy Kendon says Britain's hottest summer day could increase by 6 degrees under the high emissions scenario:
"That's a huge increase by the end of the century."
See also this story:
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