Heatwaves Are Getting Deadlier - And It’s Going To Get Worse

0:00Record temperatures have hit the US this July, with 20 states recording temperatures over 38 degrees Celsius, or over 100 Fahrenheit. There has also been a record heatwave in Europe this June, with temperature records being broken on consecutive days. And that was especially notable foreboding, you could say, as June is not even the hottest month in Europe. Right. And work by the World Weather Attribution Group, they were on the podcast last year, shows that those June heat records would not have been possible without climate change. It almost goes without saying, but we do have to say it. Yeah.

0:30And it's everywhere as well, right? In June, in Sydney, the record temperatures. India and Pakistan had a heatwave in April to May, where the temperatures got above 46 degrees Celsius in many cities. And right now we've got wildfires in southern Europe. So heatwaves is what we're getting into today. From new scientists, this is the world, the universe and us. I'm Dr Penny Sarshe. And I'm Dr. Rowan Hooper. Now there's another heat wave now rolling out over Europe. Now it takes weeks to months even longer to get actual data on what's happened, the direct cause of this, how many people have died as a result of the heat.

1:06But a new estimate has put that at over 20 ,000, which is much, much higher than the official figures so far. Alec Luna and Michael LePage have been reporting on this and join us now. Michael, take us through how they've got these figures. Yes. So this is an estimate from Christopher Callahan at Indiana University in the US. And it's based on a study that he did at the beginning of the year. So he was looking at Europe and looking at past data on deaths and temperatures. And so you get this curve when it's very cold. You get a lot of people dying as it gets towards moderate temperatures, sort of deaths reach a minimum.

1:42And then as the temperature goes up and gets high, you start seeing this big increase on the other side again. And so what he was doing is using that data to sort of predict how many deaths there will be as climate change kicks in and we get hotter and hotter heat waves. But he was able to take that relationship he had worked out and apply it to the recent heat wave, the June heat wave in Europe and say, based on what's happened in the past, I can estimate that there would have been sort of between 17 ,000 and 25 ,000 deaths just in that sort of short period. So that's astonishing, isn't it? We're talking about 20 ,000, more than 20 ,000 deaths in essentially what was one week of extreme heat in Europe.

2:23Let's talk about that heat wave. What caused it? Why was it so hot? Well, I mean, the immediate cause is you had this dome of heat. That's where you have airs descending. As air descends, you get lots of sunshine, high pressure. And of course, as air descends as well, it warms up. And that just stayed in place for ages. but you know the bigger picture is of course you know from year to year you would expect variation and if there was if the climate was stable you just have some hot years some cooler years but now that's been overlaid on on global warming so temperatures are going up and up and up and so this year it happens to be a bit warmer but because of global warming every time it's a bit warmer those heat waves are a bit hotter there's also in europe europe sort of the temperatures has been warming particularly fast, and we're not quite sure of the reasons why.

3:13But there's some evidence, for instance, we know global warming, it's affecting the jet wave that controls a lot of Europe's weather, and it seems to be leading to these sort of longer periods. So, you know, when there is this sort of high pressure blocking patterns, they stay in place for longer, and that means it can get hotter. There are also some other things. So there was a study a couple of years ago were reported on where they found that it's you know the air pollution has been cleaned up a lot in europe and that's also adding to this these increase in temperatures sort of termination shock of cleaning up our air exactly and we've talked i think we've talked about a lot in relation to the oceans and with the shipping pollution being cleared up but it's also happening in a lot of land areas as well and leading to higher temperatures talking of blocking patterns right i feel like there is a disconnect between we talk even the media other media talk about climate change and the increased temperatures but then the deaths thing seems to be a bit unconnected in the broader public to climate change but this is something we absolutely need to to talk about isn't it so many deaths um there's a paper in nature medicine i'm looking at the summer of 2022 more than 60 000 people across europe died as as a result of extreme heat in 2023 that was a bit cooler 47 000 still heat related deaths um and alec you've been digging into this bit more and one of the things that jumped out at me was the was this increase in nighttime temperatures that we're seeing yeah so they're called tropical nights which doesn't really it makes it sound almost nice like you're on holiday or something but uh but they they're actually deadly um and and they and even for those that that aren't you know killed by them they they can be very stressful So in the UK, it's above 20 degrees Celsius.

4:58When the temperature doesn't drop below 20 degrees Celsius at night, that's considered a tropical night. It used to be that there would be about 1.5 tropical nights in the UK a year. Wow. And we just had four of them in London in June. Yeah, one last night for sure. And now more in July as well. This does, I think, two things. The first is it just disrupts sleep. The body, when it falls asleep, to fall asleep and stay asleep, the core temperature has to decrease by about a degree Celsius. So if you're having a tougher time dropping your bodily temperature because it's so hot in the room, then that can disrupt your sleep.

5:38And that obviously isn't good for health in general, especially during a heat wave. But then the second thing is it just, you know, nighttime is the time when people can recover from the very hot temperatures during the day, during a heat wave. You know, you get that respite at night, able to cool down, able to rest. And if you're not able to cool down at night, it just makes it that much more difficult the next day. So that really compounds the heat stress over a period of time. And the combination of a heat stress day plus a tropical night, that combination has been increasing around the world and especially in Europe.

6:16So we're seeing kind of these longer strings of hot nights and hot days where you just can't recover. And I think a big part of the problem that we're talking about in Europe is the, you know, especially in the UK, houses are adapted to sort of stay warm. And so I know my, you know, my house, you know, all that insulation I put on the roof to sort of keep it warm in winter is now keeping the heat in during the night. And so there's a real problem with getting houses cool at night. so you know when having these extra tropical nights and then you want to fling open the windows and cool your house down but it can take a long time and it takes so much longer if you have these really high nighttime temperatures yeah i worry that in the day obviously it heats up because if we're getting to 35 37 outside inevitably the house heats up but if you can't then open all the windows at night and get rid of that heat you're starting the next day at a higher base um and we uk houses just aren't built for this are they alec you've been spending some time in a heat experiment looking at what it's like to be in extreme heat.

7:14Can you tell us about that? Yeah, yeah. Just the scientist did a small experiment on me. In the name of science, I went into the heat chamber at the Environmental Extremes Lab at the University of Brighton. And so this is essentially a small room where they can control the humidity, the temperature and the oxygen content. They use it to study different kind of environments and their physiological stress on the body. It's actually right next to the Brighton and Hove football club stadium. They've had players in from the football club to test how fit they are in the off season. But they're also looking at people during heat waves.

7:52And so I went there and they dialed in basically the conditions that we experienced in the UK in June. So 35 degrees Celsius, 50 % humidity. And before I went in, they took my baseline skin temperature, oxygen levels of my blood, my heart rate. And then there was also a couple of questionnaires about how I rated on a scale, how much exertion I was feeling, how comfortable I was feeling, and how hot I was feeling. And then we went into the heat chamber and I was walking on a treadmill at 1 % incline, which basically replicates just normal movement outside during a heat wave. And I was only in there for 10 minutes.

8:35But after just five minutes, my skin temperature had gone up by from about 33 to about 36 degrees Celsius. And as this is all happening, the scientist is standing there explaining to me what's going on in my body, which was kind of freaky. So he was saying, oh yeah, your skin temperature is going up because your body is pumping blood from your core towards your skin to try and cool your core temperature down. So that's why we're seeing this kind of spike in your skin temperature. And then my heart rate had gone from 72 to 90 something beats per minute because I was starting to sweat. And as you sweat, you're losing water, obviously.

9:16And so your blood is actually getting thicker. So your heart is pumping more. It has to work harder. So basically, we saw that when my heart rate just shooting up because my heart was working so hard to pump the blood around my body. And I only spent 10 minutes in there. But after the end of that 10 minutes, I came out and I said, how did I do? And the scientist there said, yeah, you're not well adapted to the heat. And I think that's the case probably for a lot of us in the UK. We're just not adapting. I mean, just imagine it. That's 35 degrees. People in many parts of the world are trying to work outdoors in in 40 45 degrees it's just untenable can you imagine it you can't even imagine it well you can now you can start to imagine it i mean just just walking on the treadmill for for 10 minutes at a very moderate pace you know they had me keep on rating my exertion level and it just felt so tiring yeah towards the end of that um even though it wasn't serious physical activity like a you know physical laborer would be doing and i mean And that's essentially they kind of make two big points with this research they're doing.

10:23One is that is behavioral adaptation. Our body can only do so much. We can only sweat so much. So we need to adapt our behaviors to try and cool down. And so one neat thing that they did was when I came out of that heat chamber, they sat me down and they gave me a tub of cold water and they had me immerse my hands in the cold water. and they say that this technique is the best way they've found to cool people down after they've been in the heat chamber because you have so many blood vessels, capillaries and everything in your hands and also so many nerves in there that it can cool a large volume of blood relatively quickly by immersing your hands or your feet in a tub of cold water.

11:02I've never heard that. I want to do that right now. You know, that physical exertion. I foolishly went and did park run on a Saturday after the heat wave It was only in the 20s then, but I underestimated the heat. I mean, I rarely hit a wall. I rarely struggled. And I was just absolutely drenched afterwards. Well, so the second thing that we should all be thinking about is the more bigger picture thing, which deals with exercise, first off. If you have aerobic exercise on a regular basis, your heart gets stronger, better at pumping the blood around your body. You can cool your blood down, pumping it to the skin more effectively.

11:37Secondly, repeated heat exposure. So their message really was we think of heat as just a blanket bad thing. You know, we need to get rid of heat. In fact, we need to embrace it a bit and expose ourselves to heat in advance of heat waves so that we build up a heat tolerance. And a good way to do this is going into the sauna, actually. What does it mean, a heat tolerance? How does your body get used to it? There's a bunch of different mechanisms that can kind of become more effective by repeated heat exposure. One is with vasodilation, how much your blood vessels can kind of open up and dilate to allow the blood to really flow to your skin.

12:16That can be improved. That can happen quicker and more effectively if you're building up your heat tolerance with repeated heat exposure. And then the other thing is you actually get more efficient at sweating. So if you go into a sauna a lot, let's say, you get good at starting to sweat sooner, to sweat more. So that's cooling you down. And then also your sweat actually gets less salty. So you're preserving, you're conserving more sodium, which is an important electrolyte for bodily processes. So you're actually, your body is functioning more efficiently because it's able to conserve electrolytes better.

12:53I was talking to one of our reporters in Australia yesterday, Alice Klein, and picking her brain about heat. And she was saying, for I think the same reasons that you're saying, Alec, you know, the UK is starting to embrace air conditioning. We're starting to think about getting it in our homes. and yes it can help us sleep and that sounds quite important but you don't want air con all the time because we do actually have to train our bodies to adapt to it in a way. What if the most high octane workout for the brain is just play? That's the takeaway from the latest New Scientist CoLab feature exploring how active play is a powerful brain sculpting force that operates at every level from genes to cell biology to behaviour.

13:32By designing toys with a built-in curiosity gap and then giving children the agency to explore and the freedom to fail, ActivePlay cultivates flexible, creative thinkers who generate original ideas, ask better questions and bring human empathy to their work. Head over to newscientist.com slash lego to find out how play shapes future thinkers. Sponsored by Lego. Michael, how do we get from those stresses of being exposed to heat to those vast numbers of deaths? how does that sort of translate to those statistics? Well, just picking up on Alex's point about sweating. So one of the things that happens as you get older, you get worse at sweating.

14:12It takes longer before you start sweating and you sweat less. And this is one of the reasons why elderly people are more vulnerable to the heat. And so as you see these heat waves, it is basically, I was looking at the statistics for last year, which we have in terms of age, So the vast majority of the people who are dying during these heat waves are sort of elderly, particularly, you know, 70s, 80s. But there are still a few people in their 20s, 30s who are dying as well. But the vast majority are sort of older people who are the most vulnerable to the heat and can't cope with it. I think one of the things that sort of really alarms me around that is we already know in this country, the sort of winter crisis with flu and COVID and the rest of it in hospitals is very deadly.

14:56We see all of our health services overstretched. And now potentially we're thinking in terms of also having a completely different kind of summer crisis where vulnerable people are also in real danger. Yeah, I mean, the thing to say about that is this is completely avoidable. I mean, if we adapt our infrastructure so that houses don't get too hot, then we're not going to have these kind of excess deaths. You know, this is so much you can do. A part of it with elderly people is obviously having a sort of network where they checked up on and also educating them on what to do. For instance, you know, a lot of people don't understand about the need to sort of shut windows during the hottest part of the day and shut your blinds.

15:35I think you need to keep your windows open during the hottest part of the day because people here are just not used to that kind of heat. So these basic things. Also, I was talking about older people not being able to sweat as much. spraying yourself with water is very effective obviously you combine that with a fan it's basically the same thing isn't it potentially less dehydrating as well because you're just putting the water straight on your skin and a trick i learned when i lived in japan and it's very hot and humid there is um have a wet towel in in in like a dish next to your bed and you can just lay lay under a wet towel which sounds freezing cold but it really works it actually does cool you down.

16:13But I mean, to come back to this point about the disconnect between the deaths and climate change, we are at breaking point. Like you mentioned about the hospitals, the London Ambulance Service, one of those days in June, it had a record, the record number of life-threatening emergencies in a single day at 641 call outs. So the ambulance services stretched to breaking point. A couple of hospitals declared critical incidents due to the heat wave and started only accepting emergencies. So yeah, we're already, you know, this is 1.5 degrees, we're already at breaking point. So I know you say, oh, it's all avoidable, but we've got to actually make those changes.

16:56Yeah, exactly. This is what really frightens me about these heat waves we've seen. Because I just keep thinking, well, what's coming next year in a year after that and 10, 20 years down the line. And of course, we know the answer to that. It's going to get hotter and hotter and hotter. And we're going to see sort of, you know, more extreme heat waves with higher temperatures, higher humidities that are lasting for longer, more tropical nights. You know, we can survive them if we sort of take adaptation seriously and we start changing our buildings. You know, we are going to need air conditioning in this country.

17:28I know there's some sort of people who are very opposed to that, but we are going to need air conditioning in a lot of buildings. we need to start sort of changing and adapting now but at the moment every time we have one of these heat waves and it's worse than the last one it's like it's a surprise to people oh what's happening well you've been warned about it you know climate scientists have been trying to warn you about this for decades and no one seems to be listening as you say in your story adaptation is not keeping pace with the risk exactly as climate scientists like to say this is the coolest summer we'll probably experience for the rest of our lives well on that note we'll leave it there That's all for this episode.

18:02Thanks to our guest, Michael LePage, Alec Loon, and thanks to you for listening. Do subscribe and follow wherever you get your podcasts. Goodbye for now. Goodbye.