Global warming is killing - if you look at it with one eye closed

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Global warming is killing - if you look at it with one eye closed
Global warming is killing - if you look at it with one eye closed
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The new work claims that global warming is exacerbating heat waves, thereby increasing deaths from them by thousands each year. True, the key author of this study has convincingly shown earlier that far more people die from the cold than from the heat. And it is very strange that he kept silent about the impact of global warming on the weakening of cold weather. In addition, deaths from heat waves have not increased at all in recent years, although climate change is setting record after record. But there is also a more pressing problem: the very idea that global warming leads to heat waves does not yet have a solid scientific basis. We understand the details.

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Life constantly shows: if we want to survive, we must distinguish real signals from the surrounding world from illusory ones. We recently illustrated this with an example about the author of 300 scientific papers, based on whose opinion, many residents of Russia have put their survival in jeopardy. A little earlier, Naked Science talked about, calling things by their proper names, fake scientific works of the author of hundreds of other scientific articles, already Western. But the list of such unpleasant cases is much longer than this pair. Therefore, it is extremely important to keep your eyes open, not being limited to blind faith in the written word.

A prime example is a new article in Nature Climate Change. Its authors argue that, judging by empirical data from 43 countries, 37% of all deaths in the "heat waves" in 1991-2018 did so because of global warming. It is known to have raised the temperature of the planet by about one degree relative to the pre-industrial era, which, according to the authors, intensified the heat waves. The researchers' conclusion is clear: let's fight warming. Everything would be fine if not for the details.

Methods are key in any scientific work. How did the authors come to the conclusion “37% of those who died from heat waves did so because of global warming”?

In the first step, they used regressions to establish a mathematical relationship between temperature and mortality from 732 data points in 43 countries. The dependence was different, since in some states (for example, Bangladesh) mortality from rising temperatures does not show a noticeable increase at all, and in others (for example, Sweden) it grows already at a little 20 degrees above zero. At the second stage, the authors took the temperature series of these 732 points and modeled them minus the warming that gave global climate change for 1991-2018.

Then the modeled "minus warming" temperature series were superimposed on the mortality series - and the modeled "no warming" mortality rate was 37% lower. Everything looks balanced. True, the accuracy of the estimate raises questions: the contribution of warming to mortality from heat is estimated in the range from 20.5% to 76.3%, a rather large spread. But, as will become clear below, this is not the main problem.

Here is one more significant: to date, it has not been scientifically proven that global warming leads to an increase in heat waves. The thing is that the warmest years, in fact, often give a minimum of heat waves: the increase in temperatures in them is due to the increase in winter, spring and autumn temperatures, and the summer heat is softened by abundant precipitation, as it was in Europe and Russia in 2020 year.In the same year, in the same Europe and Russia, we recall that very few heat waves were observed - despite the record high average annual temperature. The reason is that a hotter climate normally means an increase in the amount of precipitation, and they significantly soften the temperature jumps upwards.

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However, let's go meet the authors of the work halfway. Let's say someone will prove in the future that heat waves do become more frequent with global warming. What then?

Then the main problem of the new work will remain: it is based on the assumption that people, as it gets warmer, do not adapt to the rise in summer temperatures. This is why the work takes a simulated lower temperature and imposes it on mortality - which cannot be done if people are able to adapt. If they can adapt to rising temperatures, then as it warms, the specific mortality (per capita) from heat waves among us decreases. If there were no warming, the specific mortality during heat waves would be higher than without warming. That is, all the work in Nature Climate Change would be built on sand.

Hence the question: are people able to adapt to the heat and die less often from its waves?

Why are there so few people in the tropics who want to die from the heat?

The authors of the work note that mortality from heat is most often associated with the hottest (one) percent of all days of the warm season in one place or another. After the “hottest percent” (31 ° C) days in Chicago, mortality is up 36%. In Berlin, the hottest percentage of the warm season is about 28 ° C, and the death rate after it rises by as much as 57%. Why do Berliners die at 28 ° C much more often than Chicagoans after 31 ° C?

The thing is that the human body is constantly adapting to certain conditions. Any middle-aged person who tries to start running at + 30 ° C will quickly feel unwell. A healthy person running for at least three summer months will calmly endure such a temperature towards the end.

The average temperature of the hottest month in Berlin is 19.1 ° C, and in Chicago - 24.8 ° C. This is a big gap. Therefore, what is good for a Chicagoer, then death for another German.

But there are places on the planet that are warmer than Chicago, for example Bangladesh. As we have already noted, it was generally not possible to establish the temperature there, after which the mortality rate would increase: this does not happen, even when it reaches the peak values ​​for this area. Apparently, people in Bangladesh, where average annual temperatures are much higher than the average temperature of the hottest month in Chicago and Berlin, are much better adapted to the heat than Chicagoans and Berliners.

It turns out that a person can adapt to temperature: in different countries, he most obviously shows very different mortality at the same heat. But does this mean that the inhabitants of the same countries, the same places can adapt to the gradual warming that has taken place over the past decades?

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Psychologically, of course, yes. For example, May 2021 in Moscow was +1, 1 ° C warmer than the climatic norm. But if you poll Muscovites, none of them will call the past month warm. And the reason is simple: global warming in recent years has accustomed residents of the capital to higher average temperatures. In 2019, for example, May was 3.1 ° C warmer than the climatic norm and two degrees warmer than in 2021.

But what about physiology? Can our body get used to heat and less likely to die during heat waves?

Spain: how heat sensitivity "global pole" suffers from insufficiently high temperatures

The work in Nature Climate Change has a wonderful map that shows the rate of increase in mortality in one or another part of the world at the onset of the "hottest percentage" of the local warm season. Spain is marked in monstrous red there, where the "hottest percentage" can easily double the death rate. It turns out that the country should be an informative example in the question "whether a person adapts to the heat as it warms."

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There is such a scientific concept as the "temperature of minimum mortality." In cold countries it is lower (Holland - 16, 5 ° С), in warm countries - higher (Greece shows it above +30 ° С). Spanish researchers, however, have shown that the temperature of minimum mortality is not a constant at all: it changes, and very quickly.

They compared the temperatures of minimum deaths in the regions of Madrid and Seville in 1983-2018 and found interesting information. The lowest mortality rate in Madrid was at 28, 3 ° C - ten degrees higher than in Holland. But in Seville, the minimum death rate was observed in general at 35, 0 ° C, 17 degrees higher than a similar minimum in Holland. In both cases, women showed the lowest mortality slightly below this norm, and men - higher (on the graph).

This means that the organisms of the Spaniards in Seville are most comfortable with the air temperature, which almost never happens in Moscow, and for local men it is even higher than their body temperature. As soon as the thermometer readings fall below this optimal value for them, the mortality rate begins to rise. That is, the onset of temperatures of plus 33 ° C already means an increase in cold mortality among Sevillians. It is easy to guess that in the local winter there is no plus 33 ° C, which is why the situation with mortality becomes much worse. But the main thing in the work is still not a surprising conclusion that a person can die from a "cold snap" to +34 ° C. Another thing is more interesting.

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It turns out that the temperature of the minimum mortality rate for Madrid in this segment grew at rates of up to 0.58 ° C in ten years. And for Seville - at 1, 14 ° C in ten years. That is, during the life of one generation of people, the most optimal air temperature outside for them can change very quickly - faster than the rate of global warming over the same period. The work of other research groups from Spain showed similar results.

It remains to quote the authors of the work on the change in the temperature of the minimum mortality:

“One of the consequences of the impact of climate change on health is an increase in maximum temperatures and … heat waves (IPCC report for 2013). Various studies indicate that heat waves should have a clear impact on the rise in daily mortality (and the resulting economic damage) associated with high temperatures.

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Most of these studies begin with the assumption that the effects of heat on mortality remain unchanged. Also, this approach requires a fixed threshold, after which the heat wave begins. However, the assumption of a permanent effect of heat on mortality is unrealistic. (Italics ed.) Several studies show that the effect of heat on mortality is declining around the world.”

The authors' conclusion is predictable: people living in the same area adapt to rising temperatures and do it faster than the climate changes.

We add to this: the numbers they identified indicate that the bulk of the year in Spain is much colder than desirable in terms of minimizing the death rate of its inhabitants. If the average temperatures there rose, mortality would have fallen, not increased.

The general reasons for this are fairly obvious. Man as a species originated in Africa, and in places where it is much warmer than in Seville, not to mention colder places. It is not surprising that it is easier for him to adapt to an increase in temperatures up to + 35 ° С than to their fall.

Why did the authors of the article in Nature Climate Change close their eyes to earlier Spanish works?

As we can see, data for one of the most "heat-affected" countries show that people adapt to heat faster than warming increases it. Consequently, the work in Nature Climate Change is based, in the language of Spanish scientists, on the "unrealistic" assumption that such adaptation simply does not exist. Why did researchers publishing in a prestigious journal base their work on an unrealistic assumption?

To understand this easier, let's ask a question: why in general the work in Nature Climate Change only affects the impact of global warming on mortality from heat waves? After all, this, if you think about it, is extremely strange. The team of authors there is headed by Gasparini, a well-known scientist who has convincingly shown earlier that cold deaths are much higher than deaths from heat both on the planet as a whole and in the vast majority of countries. Just to quote him from 2015:

"Analysis of the largest dataset of temperature-related deaths suggests that most of these deaths are caused by moderately cold temperatures."

In numbers: the cold was responsible for 7, 29% of all deaths in the studied zones, and the heat only for 0, 42%, which is more than 17 times less. Why now Gasparini took only mortality from heat, but excluded mortality from cold? How can you recommend fighting warming, forgetting to mention that deaths from cold are more than 17 times higher than from heat?

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Take a look at the findings from the new work of the Gasparini group: "Our results provide further evidence of the potential benefits of strong containment measures against future warming …"

What would happen if we included in the work figures that mortality from cold is more than 17 times higher than mortality from heat? Inevitably, there will be a feeling that global warming is reducing the number of temperature-related deaths. By the way, this is not a sensation, but a scientific fact. Why go far for examples: in the winter of 2019-2020, 20 thousand fewer people died in Russia than in the winter of 2018-2019 - fortunately, the first was a record warm in our entire history.

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How do you then write the words “Our results provide additional evidence of the potential benefits of strong containment measures in relation to future warming …”? After all, it turns out that warming-restraining measures may well raise the overall mortality rate among people. Of course, it was objectively impossible to take into account mortality from cold in the work, otherwise it would have to end with completely different conclusions.

It is for this reason that the work completely ignored earlier studies showing that humans adapt to heat faster than global warming. If we do not close our eyes to this scientific fact, it turns out that the number of victims of the heat, intensified by global warming, is generally difficult to calculate. How to count them if the adaptation to the heat is faster than the intensification of this heat? How can an increase in the number of victims be calculated if, based on empirical data, it is generally impossible to show that such an increase in principle took place?

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The situation with Gasparini's work is fully explainable. If you are unable to publish the work given the scientific facts, you will have to do it by ignoring them.

What is less clear is: How deeply will you sleep at night after that? Wouldn't you dream of "cruel pests" that will force Nature to withdraw your scientific work - as happened to another amateur describing the dire consequences of anthropogenic carbon dioxide emissions?

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