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Charmaine Cozier
the inquiry from the BBC World Service. I'm Charmaine Cozier. Each week, one question, four expert witnesses and an answer. June 2026 an extreme heat wave moves slowly across parts of Europe. Countries breaking temperature records include Poland, Denmark, Hungary, Austria, the Netherlands and Switzerland. Germany hits an all time national high of 41.7 degrees Celsius. Weather maps turn bright red as dangerous heat alerts are activated. Events are cancelled over public health concerns in the uk, Hot expanding train tracks stop services fueling it is a weather pattern where hot air gets trapped under a large slow moving area of high pressure. It's called a heat dome. Scientists say longer term global warming impacts of human caused climate change like deforestation and burning fossil fuels are also ramping up the effect. So as countries face the prospect of more frequent spells of intense scorching weather this week we're asking can we live with extreme heat?
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Part 1 Slip Slap Slop
Ollie Jay
There's a variety of different ways in which extreme heat can impact the human body across a lot of different physiological systems.
Charmaine Cozier
Ollie J is professor of Heat and Health at the University of Sydney in Australia. He's also Director of its Heat and Health Research Centre.
Ollie Jay
I'll start off with the most obvious, which is heat stroke. This is when body temperature increases to critical levels. So 40.5 degrees Celsius or 41 degrees Celsius is often a threshold that we're concerned about. This is the core body temperature.
Charmaine Cozier
Core body temperature covers blood, internal organs like the brain, heart and liver, and also muscles and tendons. The average for humans is 37 degrees Celsius. With heat stroke, as the body overheats, blood, which helps regulate temperature, is diverted away from the core towards the skin surface to try and cool it. It also reduces the flow of blood Carrying oxygen to the lining of the intestines. That damage results in toxins leaking from the gut into the bloodstream, and then
Ollie Jay
this gives rise to widespread blood clotting, Multiple organ failure, and death. So it's a very severe condition if heat strain evolves to the point where you're experiencing heat stroke. But what's quite noteworthy Is that people with heat stroke Represent a minority of cases in hospitals and in the death statistics during heat waves. In fact, the number one killer during extreme heat events Is actually cardiovascular disease. It's the very act of them physiologically trying to keep cool that places extra strain on their cardiovascular system.
Charmaine Cozier
So not only is the body sending blood to cool the skin surface, the heart is also working harder to pump it around the body to maintain blood pressure. Extreme heat can also see the body losing more fluids Than it can replace, Mainly through sweat. That can lead to dehydration.
Ollie Jay
But it's not the secretion of sweat that cools us down. It's the evaporation of sweat. And when it's humid that results in a proportion of your sweat that you've produced not evaporating. So that, in turn, requires you to sweat even more to keep cooling, Achieve a given amount of evaporative heat loss. In terms of volumes that we sweat, it wouldn't be unusual to sweat as much as 1 liter or 1.5 liters per hour, Particularly if you are engaging in vigorous physical activity In a hot, humid and sunny environment.
Charmaine Cozier
But replacing lost fluids Isn't as straightforward as it sounds.
Ollie Jay
We don't absorb all of the water that we drink, and drinking water itself acts as a diuretic, which means that it makes us urinate more. So, as a rule of thumb, we have to drink around about one and a half times the amount of water that we've lost through sweating in order to completely rehydrate. It's really difficult to be able to drink and absorb enough water to maintain hydration. And then there's people with kidney diseases. So if you have an underlying kidney disorder, Dehydration itself places extra strain on the kidneys, which can then lead eventually to the occurrence of chronic kidney disease. If this is something that happens over
Charmaine Cozier
prolonged periods of time, Extreme heat waves are risky for all of us. But even more so for babies who can't regulate temperature as efficiently as adults and for elderly people. The head of the World health organization said 1,300 more people died than the number that would have been expected over a single week in June and linked those excess deaths to high temperatures in Europe. Advice from health officials included drinking fluids, keeping homes and workplaces cool, avoiding non essential journeys and staying out of direct sunlight when ultraviolet rays are highest.
Ollie Jay
One thing that most people don't realize is that the temperature that's on the weather forecast or on your weather app, that's measured in the shade. And so if you're out in direct sunlight, you're going to be exposed to temperatures of at least 10 or 12 degrees Celsius higher than that temperature that you think you're being exposed to. So if it's 38 degrees Celsius in the shade, then in the sun it's going to be as hot as 50
Charmaine Cozier
degrees Celsius, which means we always need to be safe in the sun.
Ollie Jay
Here in Australia, of course, we're quite well known for our public health campaign called Slip Slap Slop, which really encourages people to apply sunscreen on sunny days. I have a six year old daughter, she just started school this year and one of the things that really struck me is that they have a rule at that school that each child has a wide brimmed hat and during break time they're not allowed outside unless they have their hat on. And it's a testament to the way in which the Australian culture is really adapted to this thread. Threat of skin damage due to uv, which results ultimately in increased risk of skin cancer. I think often people misunderstand that the risk of UV is associated with how hot it is, but it's really just how sunny it is.
Charmaine Cozier
Extreme heat is a clear threat to health. It can also reshape economic activity, as our next expert witness can explain.
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Part 2 Opportunity crops
Lindiwe Magelle Sabanda
so I have been farming in Zimbabwe, in Chegutu, just 100km out of the capital city, Harare, since 1997. I'm an animal scientist, so cattle have been my main enterprise in farming.
Charmaine Cozier
Lindiwe Magelle Sabanda is also chair of council for the National University of Science and Technology in Zimbabwe. Her other responsibilities include extraordinary professor at the University of Pretoria in South Africa and a board director for the global food and beverage company Nestle.
Lindiwe Magelle Sabanda
We had Our first El Nino 9798.
Charmaine Cozier
El Nino is a natural, complex and unpredictable weather pattern that causes disruption across continents.
Lindiwe Magelle Sabanda
1997, we experienced high heat and erratic rainfall and it was declared a drought year. Luckily, my head was small. I could cope with the water that I had. Then came 2015, where we had extreme heat. That was across Africa, Asia, Latin America. But for us as farmers in Africa, the biggest challenge was lack of water for our livestock, lack of water for our cropping activities. And if that rainfall distribution is affected, if the amount is reduced, it is at times as high as 50%. Your crops fail. And those have been the challenges that we face. And since then it's been continuous.
Charmaine Cozier
Agriculture and related industries play a crucial role in many African economies. Key to that is the vast network of small scale farmers or smallholders.
Lindiwe Magelle Sabanda
I'm now a large scale commercial farmer, but I was raised on a smallholder plot which was owned by my grandmother, which is a two hectare plot. And on that two, my grandmother was able to feed her children, which is her eight children and great grandchildren, well up to 20. You have a good 70% of the population who are on the land producing food. What is the food they'll go for staples. It will have maize, it will have millet, it will have sorghum.
Charmaine Cozier
Sorghum is a gluten free cereal grain popular in many African and Asian countries.
Lindiwe Magelle Sabanda
They will have different varieties of beans, but they will also have root crops and, and potatoes, sweet potatoes. On that small patch of land we had an orchard. We also kept free ranging chickens. We had about 15 goats and two cows which produced the milk that we had with our tea every day. So the small holding entity is the backbone of most African communities because people are able to feed themselves from the land.
Charmaine Cozier
It's an essential element of national food security.
Lindiwe Magelle Sabanda
So, so they are a critical player in the economy because if they don't produce enough, government has to import to feed them and has to subsidize the import so that the farmers can afford to buy. And there's nothing as terrible as feeding a smaller farmer. They lose their dignity and it has a big hole in the economy.
Charmaine Cozier
Erratic weather is a major threat to self sufficiency. It's led many farmers to rethink how and what they grow.
Lindiwe Magelle Sabanda
If in the mainstream maize and wheat, there are varieties that the scientists have bred which are drought tolerant, those are new to us. They are helping. But diversification is a better strategy. What has been good is that in terms of policy, government has increased the floor price of cereals for the traditional maize and sorghum to be at par with the maize. So millet, sorghum and maize now command the same price. That's now attractive for us as farmers because, because we know there's a ready market which can reward the hard work of farming with a good price. Already we've seen it in Zimbabwe. All hotels have now been mandated to serve a traditional diet. Because if you came to Zimbabwe, in most African countries, Kenya, West Africa, it's the western diet that is served. But now there's a big push to go back to traditional indigenous foods, which we now call opportunity crops.
Charmaine Cozier
There are also more precise agricultural techniques. Crop rotation and covering soil with protective layers retains moisture and nutrients.
Lindiwe Magelle Sabanda
So for us, now that we know that we have the recurrent droughts, we need policies that promote climate smart agriculture. What are those policies? Number one, irrigation. Government has to step in to provide dams, dam the water and avoid losing the rainfall water to the sea. We now have to invest more in research and development to ensure that the seeds that we have are climate smart. So is smallholder farming sustainable for countries like Zimbabwe, where it's been the backbone of the economy? I say yes. And why? It's because we have to feed new technologies to keep the farmers farmers on the land.
Charmaine Cozier
That's already happening.
Lindiwe Magelle Sabanda
I'm seeing a lot of these smallholder farmers going into greenhouse production on their one acre plots. It means they are mitigating against climate change. They are also installing drip irrigation kits. They are also using solar driven boreholes. They have access to wi fi all the time. People are going back to farming because it is now modernized and it is major sector of the economy contributing 30 and in some countries up to 40% of the GDP. So we cannot let smallholder farming die. If anything, it has to be supported more than ever.
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Charmaine Cozier
Our third expert witness is nearly here. So what better time to remind you that Past episodes of the Inquiry like is technology ruining sport? Or Can Brazil's Indigenous population save the Amazon? Are available wherever you get your podcast tap like to subscribe Part 3 the
Diana Liverman
Urban Heat Island Effect
Winston Chao
Heat waves have been around for a long time. It's just that human caused climate change has made the frequency and and intensity of heat waves significantly worse in the present day. And it will continue to make it worse in the future.
Charmaine Cozier
Winston Chao is Co Chair of the Intergovernmental Panel on Climate change Working Group 2, also known as IPCC. It's the United nations body for examining climate impacts, adaptation and vulnerability issues. He's also professor of Urban Climate at Singapore Management University.
Winston Chao
So the issue is that when you have more built up areas in cities, you exacerbate the temperatures locally on top of the regional and global changes in climate and temperature. And that sort of compounding effect, or a double whammy effect, is something that really makes the levels of heat risk a bit higher for today's city dwellers.
Charmaine Cozier
It also makes those areas hotter than rural ones.
Winston Chao
The the urban heat island effect is the fact that there's elevated temperatures measured in cities and settlements relative to their natural surroundings. And it's caused by the removal of natural vegetation, your grasses and your trees. You replace it with concrete and asphalt. That stores more heat during the day and makes it warmer, especially at night. But there's also waste heat generated from air conditioning from traffic that goes into cities. That also adds on to the warmer environment that people observe and feel in
Charmaine Cozier
cities like in Singapore.
Winston Chao
So in Singapore we are low lying equatorial city, high temperatures year round, high humidity as well. We are an extremely urbanized country. 100% of our population lives in built up areas. A study that we did some time back pointed to a difference of about 7 degrees Celsius between a commercial downtown area and that of forested areas by the countryside. And and this is again on top of the long term trends in temperatures rising from climate change.
Charmaine Cozier
So what's being done to reduce the heat risk there? There's a lot of greenery which provides shade. Plants also draw moisture from soil and release it into the air as water vapour which has a cooling effect.
Winston Chao
We can call it green infrastructure, we can call it nature based solutions. It goes beyond the single street tree that you might see by the roadside. Increasingly we're seeing buildings in many cities have green walls and green roo that have small scale cooling that can be discerned by building dwellers. But also it's integrated or combined with park spaces that are not just of large size, but they're also connected. We find that the more connected these green infrastructure are in cities, the bigger the cooling effect that can really make a difference in reducing heat exposure for urban dwellers.
Charmaine Cozier
Extreme heat considerations are also built into property design, like covered outdoor walkways. There are also centralized systems pumping cold water through underground pipes to cool the inside of multiple buildings instead of the more traditional air conditioning units.
Winston Chao
So it's a combination of all these things to deal with the risk of the higher degrees of physical exposure from the heat island and from climate change that we are facing in Singapore. But we use several different approaches to try and reduce the heat risk that we'll be facing in the future.
Charmaine Cozier
Countries used to cooler climates are experiencing more frequent, longer and intense extreme heat. The ideal response is weighted more towards being proactive than reactive.
Winston Chao
There are many cities in India that have very well developed heat action plans. They work together with meteorological agencies to get the right level of early warning through forecasting or through models. And with that knowledge at that early stage, you can prevent the worst impacts of heat waves by quick communication with particularly vulnerable communities. That sort of prevention aspect really makes a massive difference in terms of life saved and in terms of lower morbidity events that usually happens from heat waves.
Diana Liverman
Part 4 Bridging the Heat Divide it's clear that a lot of vulnerable people are having a much harder time coping with heat extremes than those who are better off and less disadvantaged.
Charmaine Cozier
Diana Liverman is professor of geography at the University of Arizona in the city of Tucson in the US
Diana Liverman
and we're seeing this all over the world, not just the global south majority world, but also of course in Europe and across the United States where we have very high heat extremes, especially where I live in Arizona, which is the hottest state in the US and getting hotter. So, for example, if you take Tucson, we used to have on average 12 days above 40 degrees C. We now have 28. Phoenix, which is the hottest large city in the country, used to have 20 days above 43 degrees C. And in 2024 they had 70 days. So we're definitely seeing the impact of warming temperatures and climate change across the state.
Charmaine Cozier
Extreme heat inequality impacts different groups of people in different ways.
Diana Liverman
We have a high proportion of single moms living in poverty, and we know that many of them are having to choose between paying their energy costs, which will provide them with air conditioning, or feeding their kids. And they also may not be able to access the most nutritious food, which will make everybody in the household more vulnerable to heat extremes. And I think another key Thing is, people who work or live outside. So across the world, farm workers are very vulnerable to extreme heat. Here in Arizona, construction workers, people who work in people's gardens, and then of course, the unhoused, the homeless who are living outside during these terrible heat waves. And in most parts of the world, poverty intersects with race and ethnicity. So people of color are often more vulnerable because they're poor and discriminated against. And also, indigenous folks in many parts of the world can be very vulnerable to extreme heat.
Charmaine Cozier
One form of lower cost accommodation, mobile or manufactured homes in trailer parks, can also widen the divide.
Diana Liverman
I mean, you have these quite beautiful trailer parks that are lived in by better off retirees with gardens and trees and reliable access. But then there are a lot of poorer people living in very broken down trailer parks with really old trailers with thin walls with no insulation.
Charmaine Cozier
Heat emergency procedures in major cities in Arizona are addressing some extreme heat imbalances.
Diana Liverman
In Tucson, for examp example, we have cooling centers where people can go during extreme heat. One of the things we figured out is they need to be able to take their pets because they don't want to abandon them, who are also very vulnerable to extreme heat.
Charmaine Cozier
There's also free transport to those heat relief centers which have free cold drinks and snacks.
Diana Liverman
We also have tree planting programs that are providing shade in some of the poorest areas of Tucson where there isn't tree cover that can reduce temperatures. Everybody in Arizona is threatened by the drought on the Colorado river, which comes to many urban areas. But one of the problems, for example, with having trees around your house is during these heat waves, you actually need to irrigate your trees. And many people come afford to do that. There are places in the southwest, for example, on indigenous lands where people don't have good access to running water. The droughts are making the wells decline. And the big problem with extreme heat is you're going to have more evaporation and that means less water. So people are having to spend hundreds of dollars just to keep a vegetable garden going in this extreme heat. There are going to be a lot of people suffering if we don't act faster and more seriously on climate change.
Charmaine Cozier
So back to our main question. Can we live with extreme heat? Yes, but only if the means to adjust to it are available, affordable and sustainable. That goes for countries with tropical climates and cooler ones where buildings are designed to keep heat in. Whether the measures to tackle future record breaking hot spells are more proactive or more reactive is also crucial. Last word to our expert witness, Winston Chow.
Winston Chao
Cities don't have much of a choice. It's either we adapt or we face the consequences of of not just higher heat risk, but other sorts of climate driven impacts like droughts and floods and sea level rise that many cities will face in the years to come. So if you don't adapt, then you're going to have to pay the consequences of a significantly warmer world.
Charmaine Cozier
Thank you for joining us. To find past episodes like can the New World Screw Worm be Stopped? Or why Does Mexico Owe the US Water? Look for the Inquiry podcast wherever you get yours, tap. Subscribe for Updates this episode of the Inquiry was written and presented by me, Charmaine Cozier. The producer was Jill Collins, researcher Amelia Cox, editor Tom Bigwood and technical producer Cameron Ward. A Moment in time Captured by what
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they heard I heard some people making phone calls.
Winston Chao
Okay, which Runway would you like at Teterboro?
Charmaine Cozier
We're gonna begin to what they saw
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I put my head down, I saw
Winston Chao
the movie of my life started going
Charmaine Cozier
through my head what they smelt.
Lindiwe Magelle Sabanda
I still remember the smell of the
Diana Liverman
fresh fish and I completely lost my appetite.
Charmaine Cozier
Moments captured which last for a lifetime. Scientists have made the atomic bomb that
Diana Liverman
sort of flash set on fire the birds and they all fell down without
Winston Chao
their feathers on the way was clear
Ollie Jay
for Hitler to realize all his demonic plans.
Charmaine Cozier
Stories from people with first hand accounts of events that have shaped our world.
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At the end, Kissinger called me into his office and he said, you did a good job. I left the office with tears in my eyes.
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She called me and told me I'm doing Studio 54.
Charmaine Cozier
She had already become a star in Paris.
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She came back a superstar.
Charmaine Cozier
Listen now. Search for witness history wherever you get your BBC podcasts.
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BBC World Service | Host: Charmaine Cozier | July 28, 2026
This episode of The Inquiry examines the pressing question: Can we live with extreme heat?
Amidst record-breaking heatwaves across Europe, the show explores the science, health risks, economic costs, urban challenges, and inequities created by the world’s rising temperatures. Through four expert witnesses, the inquiry delves into how human bodies, food systems, cities, and societies cope—or fail to cope—with greater heat, and what adaptations are needed for a hotter world.
Expert: Ollie Jay, Professor of Heat and Health, University of Sydney
“People with heat stroke represent a minority of cases … The number one killer during extreme heat events is actually cardiovascular disease.” — Ollie Jay [03:41]
“We have to drink around about one and a half times the amount of water that we’ve lost through sweating in order to completely rehydrate.” — Ollie Jay [05:11]
“The temperature that's on the weather forecast … that's measured in the shade. … in direct sunlight, you're going to be exposed to temperatures at least 10 or 12 degrees higher.” — Ollie Jay [06:24]
Expert: Lindiwe Magelle Sabanda, Zimbabwean Farmer & Food Policy Leader
“You have a good 70% of the population who are on the land producing food … small holding entity is the backbone of most African communities.” — Lindiwe Magelle Sabanda [09:28]
“There’s a big push to go back to traditional indigenous foods, which we now call opportunity crops.” — Lindiwe Magelle Sabanda [12:00]
“People are going back to farming because it is now modernized and … contributing 30, and in some countries up to 40%, of the GDP.” — Lindiwe Magelle Sabanda [13:17]
Expert: Winston Chao, Co-Chair IPCC Working Group 2; Professor of Urban Climate, Singapore Management University
“You exacerbate the temperatures locally on top of the regional and global changes … that sort of compounding effect … makes the levels of heat risk a bit higher for today's city dwellers.” — Winston Chao [15:34]
“The more connected these green infrastructure are in cities, the bigger the cooling effect that can really make a difference in reducing heat exposure.” — Winston Chao [17:58]
“You can prevent the worst impacts of heat waves by quick communication with particularly vulnerable communities. … That sort of prevention aspect really makes a massive difference.” — Winston Chao [18:45]
Expert: Diana Liverman, Professor of Geography, University of Arizona
“Phoenix … used to have 20 days above 43°C. In 2024 they had 70 days.” — Diana Liverman [19:47]
“Many [single mothers] are having to choose between paying their energy costs ... or feeding their kids.” — Diana Liverman [20:42]
“If it’s 38°C in the shade, then in the sun it’s going to be as hot as 50°C.” [06:24]
“There’s nothing as terrible as feeding a small farmer. They lose their dignity and it has a big hole in the economy.” [10:35]
“Cities don’t have much of a choice. It’s either we adapt or we face the consequences of ... a significantly warmer world.” [24:44]
“We’re seeing this all over the world ... people who work or live outside ... are very vulnerable to extreme heat.” [20:42]
“There are going to be a lot of people suffering if we don’t act faster and more seriously on climate change.” [23:59]
Can we live with extreme heat? The answer, as the episode highlights, is "yes, but only if the means to adapt are available, affordable, and sustainable—for everyone."
Adaptation is possible, but it requires:
“If you don’t adapt, then you’re going to have to pay the consequences of a significantly warmer world.” — Winston Chao [24:44]
For more in-depth explorations, subscribe to The Inquiry wherever you get your podcasts.