Heatwaves: how hot can it get?

from Spain to Siberia the world is experiencing record heat India suffered its hottest March in more than 100 years the heart of England today hotter than the Caribbean and the heart of Western Sahara today made history again and as Mercury rises too Does the death toll Hospital admissions increase is a deadly sign of what is to come: the body can no longer cool down at all. The heat wave is turning deadly. Now it starts cooking from the inside out. What turns a hot day into a heat wave and how that process is affected. Because of climate change, what is considered a heat wave depends on where you are in the world.

Heat wave is actually not a very well-defined term when you have a temperature that is a little above normal for that time of year for a persistent period of time. Over a period of time, someone somewhere will define that, as a heatwave in the UK, a heatwave can be declared after three days of over 25 to 28 degrees, depending on the region of New York, It must be at least three days of 32. degrees or higher, while in the Indian plains a heat wave can be declared when temperatures exceed 40 degrees and 4.5 degrees higher than normal for two days. Heat waves are a normal part of the climate system, but how do they factor into the heart?

Of many heat waves it is high pressure, the atmosphere is a sea of ​​air and if there is a particularly large amount of air accumulated over a particular place, then the air pressure increases and becomes high pressure. Areas of high pressure are known as anticyclones. rotating air masses that blow clockwise in the northern hemisphere as the air moves away from the high pressure center at ground level, the air from above moves downward to take its place, the air that sinks is actually getting hotter because it compresses in the same way as a bicycle pump heats up when you pump it and that not only makes the spot hotter, it also stops the processes by which that spot normally would cool, which would be by having convective air rising and clouds forming in mid-latitude places like the UK and US the polar front jet stream determines where the high pressure will occur.

It is a core of very strong winds that blow from west to east between 8 and 11 kilometers above the Earth's surface. People who cross the Atlantic by plane will know that it is often a little faster. if you come from America to Europe than if you are fighting the jet stream that is going in the opposite direction, the jet stream does not move in a straight line but it meanders. Around the world, low pressure areas are located in valleys and high pressure areas form in The Ridges when the twists and turns of the jet stream are particularly amplified, these lows and highs become sluggish when a maximum you end up stuck in one place it's known as a block these can persist for weeks or even months when I have one of these blocking systems running the rest of the weather basically you try to stop it or get around it um and that means you get this eye of stability, uh, where the crash happens, that's where you get the really nasty stuff.

Heat Waves Heat can perpetuate itself when the sun sets on a summer day, much of its energy being spent evaporating water into soil moisture or food plants. As the heat increases day after day, you start to run out of soil moisture and that heat that used to get into this latent heat of evaporating water just sticks in there and warms things up. This process is amplified when air descending from the anticyclone traps heat like the lid of a pot, creating what is sometimes known as a heat dome. it becomes this kind of weight of oppression that cannot change by itself that cannot be undermined this process developed in the heat wave of 2021 in the Pacific Northwest of America and Canada Vancouver, a city that is baked once more tonight in a record heat wave one that is called not only historic but dangerous the heat wave surpassed the national maximum temperatures day after day setting a new record of 49.6 degrees Celsius a political letter finally caught fire the heat wave of left-wing scientists basically stunned because they really hadn't foreseen something like this happening, the waves broke records on every continent in 2022, but it's when countries aren't prepared that temperatures can be deadly between 2000 and 2019.

The South Asia recorded more than one hundred and ten thousand deaths due to excess heat per year and in America the heat is responsible for more deaths than tornadoes, hurricanes or floods, heat waves do not have the drama of many other major meteorological phenomena, However, they kill a lot of people and that is why they are sometimes called the hidden killers or the invisible killers. In some climates like India, heat and humidity can be a lethal combination. Humans like landscapes. They cool down through evaporation, we sweat and the sweat evaporates and that takes away the heat.

If the humidity in the air is high, then that is a less efficient way to cool down, so the higher the humidity at a given temperature, the hotter you will actually feel. The so-called wet bulb temperature measures heat stress and provides an indication of the danger to human life. It is measured by wrapping an old-school mercury thermometer in a damp cloth if you have the thermometer wet. bulb temperature above about 35 degrees Celsius, that is, above body temperature, the body can no longer cool down at all and begins to cook from the inside out, even young and healthy people will die after about six hours with this heat and humidity, humid bulk temperatures. are on the rise, many countries have already reached a wet bulb temperature of 31 degrees and some weather stations in South Asia, the Persian Gulf and the southwestern coast of North America have recorded wet bulb temperatures close to or above 35 degrees Celsius. for short periods.

I'm Elliot. I work with films from The Economist. If you'd like to read more of our extreme weather coverage, why not subscribe to The Economist? You will receive daily and weekly analysis of global issues. You can read us online in the app or listen to the audio edition to get the best deal, click the link High temperatures may be unbearable, but they are not always the direct cause of deaths around the world. Excessive heat will make it difficult for people to breathe and put stress on their lives. circulatory systems this is particularly bad for older people or people who have underlying diseases and it is not always the hot days that are the deadliest, the so-called tropical Knights where the temperature does not drop below 20 degrees Celsius but is increasing in many countries No It's entirely clear why this is associated with mortality, but there's something about the very disturbed sleep people have during such events that seems to make it more likely that some of them will die.

Incredibly, even simple adaptations can save lives, but being prepared is in most places where there has been a horrible, deadly and unexpected heat wave; Then, determine what they should have done and try to implement policies and habits that would make things better next time—the trick is to learn the lessons before you take the heat. wave something France realized when a heat wave in 2003 killed 14,000 people. One of the reasons it was particularly lethal was that France simply hadn't seen itself as the kind of place that has heat waves like that, so many lessons were learned. In France, both on a personal and institutional level, one of them was that you have to control people if you have any concerns about them.

Another is that you have to find a way to get people, especially older people, people who live in precarious housing, to places that were refrigerated. School gyms, for example, turn out to be something that works very well unless they adapt now. Countries that are not yet experiencing the most extreme heat will be particularly susceptible to the kinds of areas people are concerned about where heat waves historically haven't been seen as much. But where they could cause a lot of damage is in Afghanistan, other parts of Central Asia and also parts of Central America, adaptation will be increasingly important as climate change continues to increase atmospheric temperatures.

Often, the role of climate change in extreme weather conditions is a bit subtle that if you make the planet hotter you're going to make heat waves hotter, and a relatively new area of ​​science is key to understand the impact that the idea of ​​climate attribution is in determining how likely a given event you just saw is due to global warming compared to how likely it would have been without that pioneering global warming attribution study focused in the 2003 heat waves in Europe responsible for 70,000 deaths. The researchers involved concluded that heat waves like the 2003 heat wave were now about twice as likely as in the pre-climate change world.

Evidence has accumulated since temperatures in Siberia in 2020 reached 38 degrees Celsius, the highest ever recorded north of the Arctic Circle. Researchers say climate change made this heat wave 600 times larger. chances are you're basically saying this is yes that would never be seen without climate change the mechanism is simple greenhouse gas emissions have raised average atmospheric temperatures by at least one degree Celsius from pre-industrial levels a small change on the average makes the really unlikely high temperatures in the extreme tail much more likely, if the atmosphere continues to warm you will see worse heat waves than we have seen historically and you will see them over larger areas.

There are predictions that, under some fairly extreme warming scenarios, we could see wet-bulb temperatures that make areas basically uninhabitable become quite common in some parts of the world, but scientists still don't understand how climate change will affect atmospheric circulation patterns that cause heat waves. The question of whether the strange things that cause high-pressure domes will persist in particular places, whether they become more or less likely some models say yes some say no contradict each other whatever answer humanity needs to act now even after the levels of greenhouse gases in the atmosphere stabilize and with them one hopes In the climate, there will still be many more heat waves because the average temperature of the planet will be higher.

Governments must do more to protect their populations, not only national governments but also municipal governments. Local governments, at the same time, people must understand the risks so they can protect themselves and, crucially, others. I'm Oliver Morton. I'm a senior editor at The Economist. For more information on our coverage of extreme weather and climate change, click the link and also, if you would like more information on this, please. Subscribe and as you do now, in which case thank you very much.