Around 450,000 people worldwide could die by February as a result of hotter weather caused by the record-breaking El Ni単o, climate scientists are warning. The estimate is based on how many deaths have resulted from past temperature extremes around the world.

���We���re hoping this information is actionable, that decisions can be made to move resources ahead of time,��� says at the Rhodium Group, an independent research provider. This could include assigning health workers to check on the most vulnerable, ensuring people have enough water and providing fans or air conditioning.

Most of the deaths in the next six months will be in the southern hemisphere, because the extra heat will coincide with spring and summer there. But El Ni単o is expected to persist into the northern hemisphere���s spring, so there will be another wave of deaths there after February.

���We���re going to see anomalously high mortality numbers move north,��� says Grover-Kopec. ���I fully expect these numbers to get bigger, unfortunately.��� India and Pakistan could be hit especially hard, she says.

Grover-Kopec and her team���s projection of 450,000 deaths, published in a by the Climate Impact Lab at the University of Chicago, is based on the observed relationship between temperature and excess deaths. This is a U-shaped curve, with more deaths occurring in extreme cold or heat, but its precise shape varies from place to place depending on whether the people and infrastructure are adapted to heat extremes, say, or can afford things like air conditioning.

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A divided the world into 24,000 regions and estimated this relationship for each one, based either on historical data going back decades or on extrapolating from similar regions. Grover-Kopec and her colleagues have now combined this approach with the seasonal forecast from the European Centre for Medium-Range Weather Forecasts (ECMWF) to estimate how many more people than usual could die as a result of heat caused by El Ni単o.

The results suggest that over the period of the six-month forecast, from September until February, there will be 240,000 additional heat-related deaths. Adding the deaths estimated to have already occurred since the current El Ni単o started in June takes the total to 450,000.

Africa will be hit hardest, the team estimates, with over 30,000 extra deaths in Nigeria alone in the next six months. There could be 19,000 extra deaths in Indonesia, 16,000 in India and 13,000 in Brazil over the same period.

The report divides people into three age groups: 4 or under, 65 or above, and the rest. ���There are effects across all three age groups,��� says Grover-Kopec. ���The most sensitive group is that oldest group, followed by the infants.���

���I do find these results plausible,��� says at Indiana University Bloomington. ���El Ni単o will bring very high temperatures to much of the world, and the relationship between heat and mortality is consistent and reliable across the world.���

Callahan recently used a similar approach to estimate that the June heatwave in Europe killed 20,000 people. So far, 35,000 extra deaths in Europe attributable to the heat over a longer period of the summer.

The projection of 240,000 additional deaths between September and February depends on the forecast being right, says Callahan. The ECMWF forecast sits right in the middle of other forecasts, says Grover-Kopec, so it represents a moderate view of what could happen.

The report also looks only at heat-related deaths, Callahan points out. ���El Ni単o influences wildfire in Indonesia, infectious disease in South America, flooding in the western US and so on. So, the total death toll may be higher.���

���The most important message is not the absolute number itself, but what can still be done to reduce preventable harm,��� says at the University of Warwick in the UK. ���The report is best viewed as a call to strengthen anticipatory governance, preparedness and targeted adaptation measures, particularly for at-risk and vulnerable populations.���

A heatwave in May set monthly temperature records across Europe; a heatwave in June became the hottest ever observed in western Europe. Now, in July, yet another heatwave is developing. Just 50 years ago, the June heatwave would have been virtually impossible. But global warming is making heatwaves more frequent, longer and more intense.

Worldwide, heat is the deadliest type of weather, killing more than each year. The number will increase, since even if we reached net zero tomorrow, the carbon dioxide we have already emitted will keep raising temperatures.

���This is just the start,��� says at University College London. ���Things are unfolding in a very, very major way now, because this isn���t just about it [being] too hot in London, and the long-term effects are going to be savage.���

Outside the tropics, the time of the year in which temperatures above 32属遺 occur has lengthened by 12 days in the past half-century. In Europe, the fastest-warming continent, the season of strong heat stress now starts on average in June and continues until almost September. Sometimes, like this year, it starts in May.

That increases people���s exposure to hot days and heatwaves. Parts of North America, Europe, South America and Africa now experience up to 50 more days of strong heat stress compared with the 1970s.

���If you���ve got heatwaves that last longer, and then you���ve got more heatwaves, people are going to be in that raised physiological state for longer,��� says Neil Maxwell at the University of Brighton, UK. ���That can lead to greater inflammatory marker responses, and that ultimately puts a greater stress upon individuals.���

Strong heat stress almost never occurred at night before 1998. But now, nighttime temperatures in western Europe and other places are increasing at of global warming as a whole.

A drop in body temperature triggers sleep. If the environment is too hot, it is harder to fall asleep, as well as to enter a state of deep sleep. And loss of sleep over several nights in a row can hinder reaction time and boost anxiety and stress.

���If you don���t get cooling periods at night, which we define in this country as less than 20属遺 at night, sustained temperatures without cooling have worse impacts,��� says Montgomery.

The hottest summer ever seen led to apocalyptic scenes in Europe in 2022. Wildfires broke out in France, Portugal and Spain. Italy���s longest river, the Po, ran dry in places, and wrecks of Nazi ships full of explosives were discovered as the Danube fell to record lows. In the UK, temperatures exceeded 40属遺 (104属F) for the first time.

More than 60,000 people died because of these baking temperatures. The highest mortality rates were in Mediterranean countries, which had some of the biggest temperature anomalies, with temperatures reaching higher than 40属遺 in Italy, Greece and Spain. These countries also have some of the , whose bodies aren���t as resilient to heat and who are more likely to have chronic illnesses.

���You also get inflammatory responses from heat, so heat exposure in itself triggers all sorts of bad biology in your body, basically, that is directly harmful��� and in particular in people with diseases,��� says Montgomery.

The frequency of a heat stress day followed by a tropical night of at least 20属遺 has increased 73 per cent in Europe since the 1970s. These are called ���compound events��� because the body isn���t able to cool down and recover at night, compounding the heat stress.

Europe has also seen prolonged periods of heat stress become more common. And Africa is now almost three times more likely to suffer hot spells lasting three-quarters of the year or more.

Leaders like US President Donald Trump have made pledges to plant millions of trees while increasing CO2 emissions. But in the case of urban heat, trees can make a big difference. They create areas of shade, and they also draw moisture from the soil, which then evaporates from their leaves, cooling the environment. Neighbourhoods with tree canopies can be as much as than similar places.

But although many cities have started planting trees to deal with heat, a recent found that many still have swathes of territory below the 30 per cent canopy cover that can reduce dangerous heat island effects. More than 90 per cent of the buildings in Paris and London fall below this threshold.

掘顎姻看沿艶���s most extreme heatwave so far may have killed between 17,000 and 25,000 people, according to an early estimate based on past deaths from heat in the region.

���These numbers are preliminary,��� says at Indiana University. ���But they highlight the need for rapid adaptation investments to avoid these impacts in the future.���

Callahan���s estimate is based on . ���We���re taking data on temperature and mortality across Europe, and we are correlating how high temperatures relate to excess mortality rates,��� says Callahan. ���We then use that relationship to infer how a given heatwave affects mortality over a region like Europe.���

Callahan���s conclusion is that the heatwave in Europe from 22 to 28 June 2026 killed approximately 20,390 people, including 5210 in France, 4543 in Germany, 3163 in Spain, 2709 in Italy and 862 in the UK. These numbers are much higher than the direct counts announced so far, but this isn���t surprising because it takes time for data on deaths to be collected and analysed.

���This figure is a modelled estimate rather than a final count, and it will be some months before the true toll is confirmed, in part because heat rarely appears on a death certificate,��� says at the University of Warwick in the UK.

For instance, on 28 June, the head of the World 91弼秤頭 Organization, Tedros Adhanom Ghebreyesus, said so far. This number is largely based on reporting around 1000 more deaths in the country than expected from 24 to 26 June.

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However, that statement made it clear that this number is based on a computerised death certificate system that is far from complete. It records 80 per cent of hospital deaths, 45 per cent of deaths in long-term care facilities and 25 per cent of deaths at home. ���Mortality will consequently be higher than these initial figures suggest,��� the statement said.

Even so, other experts think Callahan may have overestimated the numbers. ���Twenty-thousand for a single week seems very large,��� says at the University of Bristol in the UK. ���We���d have to look into details of the modelling to be more sure.���

While Callahan���s method is sound, the main issue is that he used data from 2015 to 2019 to calculate the relationship between heat and deaths, says at Pozna�� University of Medical Sciences in Poland. People may now be less vulnerable due to ongoing adaptations, such as increased access to air conditioning, . Walkowiak���s back-of-the-envelope calculation is that if this is taken into account, the actual number of deaths would be around 15,000.

Callahan is sticking to his guns. ���We don���t have very strong evidence that the relationship between temperature and mortality dramatically changed over time,��� he says. ���So it���s not obvious it���s different now than it was 10 years ago.���

���In general, we find that our sort of broader statistical estimates give higher numbers than direct reporting on the ground, because that direct reporting can often miss people who die from heat where it���s not obvious that heat was the cause,��� he says.

On the flip side, Walkowiak says that Callahan hasn���t taken into account the fact that heatwaves of the same temperature are more deadly in early summer than in late summer. ���In late summer, part of the especially vulnerable population is already long gone,��� he says.

Mitchell also says the kind of approach used by Callahan also counts only the immediate deaths. There can be longer-term impacts, such as more deaths from domestic violence, suicides and kidney failure. ���The impacts of heat on health vary a lot across timescales,��� he says.

What matters most is avoiding further deaths as the planet warms further and heat becomes more extreme, says Nunes. ���The signal is clear: heat is now the deadliest weather hazard we face, and the majority of these deaths are preventable,��� she says. ���We can now forecast these events with considerable accuracy; what we have not done is build the systems, across health, housing, social care and transport, for example, that translate an accurate forecast into actual protection. Adaptation is not keeping pace with the risk.���

I���m finding the heatwave hitting Europe really scary. It���s bad enough in itself, with many records being broken, especially for the higher nighttime temperatures that make it so much harder to cope. But I just keep thinking, ���If it���s like this now, what���s it going to be like in 10, 20 or 30 years��� time?���

The answer, of course, is hotter and hotter and hotter. In the UK, national weather service the Met Office has just warned that, by 2056, there could be , with some places hitting 45属遺 (113属F). In just 30 years! I���ve seen at least one piece asking ���is this the new normal?��� about the current heatwave, but we���re never going to have normal in our lifetimes again ��� just ever more extreme heat.

It���s possible to get through even worse heatwaves than this if all your infrastructure and systems are geared up to cope. But the UK is very much not prepared. The air conditioning in New Scientist���s office, for instance, is failing to keep up with the heat as I write ��� and lots of people have to endure this hot weather without any air conditioning at all. In a sign of the times, a meeting on adapting to extreme heat ��� part of London Climate Action Week ��� got .

Climate scientists are continually warning of the need to prepare for hotter heatwaves, worse droughts, more flooding and rising seas. During heatwaves like this one, they might even get a little media coverage. But then the weather cools, the news agenda moves on and nothing is ever done.

That���s not just my view ��� it���s the official verdict of the UK���s Climate Change Committee, which advises the UK government. ���Adaptation progress is either too slow, has stalled, or is heading in the wrong direction,��� it said in last year. Everyone seems to assume this green and pleasant land is going to remain green and pleasant, but it won���t. We���re heading towards catastrophe, but never looking up.

There are many aspects of this that frighten me. Firstly, emissions are still rising, so the fundamental cause of the problem is getting worse. True, it���s not getting worse as fast as it was, but we are currently , and possibly even more.

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Even these alarming numbers are a little misleading because the oceans that cover most of the planet don���t warm as fast as the land. Average land temperatures are therefore going to go up by a lot more than the above numbers imply.

And what really matters to us is extreme weather, not the average. The projections for future extremes are already dire, and there are reasons to think that we���re in for extremes even greater than those currently projected for a given level of warming. For starters, heatwaves are already more extreme than projected in some parts of the world. One reason for this is that climate models may not be capturing how the dynamics of the jet streams change in a warmer world. Another is that regional models haven���t accounted for reductions in sunlight-blocking air pollution.

The next level beyond is how bad the knock-on effects of this extreme weather will be. These kinds of things are very difficult to project because so many complex systems are involved, but here, too, there is reason to think we are underestimating the impacts.

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For starters, we could see mass deaths even among young people as heatwaves get more extreme. Then there���s our ability to feed people, the basis of civilisation. There���s growing evidence that global warming is already hitting food production, pushing up prices and causing yet more deforestation as farmers try to compensate.

As ever more weather extremes hit the world at the same time, the economic impacts are going to get ever more serious, too. One 2024 study warned that the result could be the worst global financial crisis ever.

And I haven���t even mentioned the wild cards, such as the Amazon drying up or the Atlantic Meridional Overturning Circulation shutting down. One researcher I chatted with at a recent conference thinks a slowdown of this crucial current system around 12,000 years ago triggered extreme seasonality in places like Britain, with sweltering summers, but temperatures plummeting tens of degrees below freezing in winter.

The fact is, the world is changing fast and we need to change just about every aspect of our lives to adapt ��� our homes and offices, factories and schools, cars and trains, farms and gardens, and so on. But it���s not happening.�� That���s why if you���re not scared witless by this heatwave, you should be.

With Europe in the grip of a mega heatwave and deaths already being reported, staying cool isn���t just about comfort ��� for many, it is a matter of life and death. Many people will be relying on fans rather than air conditioning, so it is important to be aware that, as it gets hotter, fans can flip from cooling you to warming you.

But how hot is too hot? The UK government warns , whereas the World 91弼秤頭 Organization says . Some studies suggest even lower or . The reality is that there is no simple answer, as several factors are involved.

The key thing to know is that you become less good at sweating as you age, so fans will start to warm you at a lower temperature than is the case for younger people. However, you can compensate for this by spraying yourself with water or wetting your clothes.

The situation would be very simple if we didn���t sweat. Our skin temperature in the shade is typically between 35属遺 and 37属遺 (99属F). If the air temperature is lower than our skin temperature, heat is transferred to the air, cooling us, but if it is higher, we gain heat from the air. Moving air over our skin with a fan speeds up this heat transfer, whichever way it is going.

Because of this, in the past, 35属遺 was often said to be the point at which fans stop cooling us, says in the UK. But this number doesn���t take account of evaporative cooling.

The evaporation of water transfers lots of heat from our skin into the air, cooling us even when air temperatures exceed skin temperatures. But blowing air over our skin with a fan doesn���t necessarily cool us more if it���s too dry or too humid.

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When it is very dry, our sweat can evaporate as fast as we produce it. In this situation, turning on a fan won���t help, because evaporation cannot increase any further. Instead, the moving air will just transfer more heat to your skin. For instance, modelling and experiments show that at 15 per cent humidity and 45属遺, turning on a fan will almost certainly .

But as the humidity rises, evaporation slows because there���s already lots of moisture in the air. Basically, if you are dripping with sweat, you are producing sweat faster than it can evaporate. In these conditions, a fan does help.

For instance, a fan can still cool you at up to 60 per cent humidity and 38属遺. As the humidity gets even higher, however, evaporation will slow to a point when a fan stops helping.

���So it depends on the humidity in the air,��� says Havenith. ���That���s why people often look at what kind of climate you have in different countries.���

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The other big factor is age. As we age, our body temperature and skin temperature can fall. It also takes longer for us to start to sweat, and we produce less sweat. This means the temperature at which a fan will start warming us at a given humidity declines as we age.

In this situation, wearing wet clothes or spraying ourselves with water can help. This can also reduce sweating and thus reduce the risk of dehydration.

Many other factors also play a part, such as clothing and whether your body is adapted to high temperatures. The bottom line, however, is that if you live in a building that gets really hot, temperatures during this heatwave could well exceed the level at which fans will help, even if you���re spraying yourself with water.

���At that stage, you probably would have to leave your house and find a cooler place,��� says Havenith. ���Because it���s a really bad situation.���