Heat waves and climate change:against the deniers

The weekly round-up on the climate crisis and data on carbon dioxide levels in the atmosphere.

These days a heat wave is crossing three continents:Europe, Asia, North America.Extreme temperatures are being recorded across much of the Earth's northern hemisphere.The month of June this year was the hottest so far recorded. The return of El Niño, the cyclical phenomenon that causes the surface of the central-eastern Pacific Ocean to warm, contributes to pushing up the planet's temperatures. There's a good chance that 2023 will become the warmest year on record.But even if it doesn't reach first place, displacing 2016, we are certain that it will be among the top positions.The ten hottest years they are concentrated in the last decade.It is not a coincidence, it is one of the many evidences of the reality of anthropogenic global warming.

🌡️ Extreme levels of heat are affecting large parts of the Northern Hemisphere

⚠️ Exceptionally high temperatures are breaking records in places and dangerously hot weather will continue in many areas during the next week pic.twitter.com/zebYqdZXGH

— Met Office (@metoffice) July 17, 2023

Even in the face of this reality, the drumbeat of denialism does not stop making noise.In fact, he plays the same old music.The same, repetitive, notes, like those in the song Is it hot?It's summer.Unfortunately, it is much easier to repeat this music than to read and explain what decades of scientific research have produced.This is the asymmetry between correct information and misinformation.

The summer heat we experienced just a few years ago has little to do with what we are witnessing now, with ever greater frequency.The heat waves of recent years have been clear evidence of global warming.20 years have passed since that in 2003 hit Europe, causing more than 70 thousand deaths.Today it is considered the first event for which it was possible to evaluate the impact of global warming.The study was published in 2004 in the journal Nature by the climatologist of the British Hadley Center Peter Stott and two other scientists.

Until then, even if the reality of global warming was now a scientific fact, it was thought that it was difficult, if not impossible, to correlate it to a single event, such as a heat wave, a drought, or extreme precipitation.Just in 2003, Oxford University climate scientist Myles Allen, one of the authors of the 2004 article on Nature, he wrote, on the same magazine, that it would be possible to develop a method that could allow us to answer this question:Compared to the probability of a specific event occurring, what fraction of this risk can we attribute to anthropogenic global warming?

It's a bit like playing with loaded dice.Greenhouse gas emissions, produced by human activities, insert a game-changing element into the climate system.The attribution studies they do this:through climate models they compare the world we live in with an alternative world, in which our emissions do not exist.“We estimate that it is very likely (>90% confidence level) that human influenza has at least doubled the risk of a heat wave exceeding this magnitude level,” wrote the authors of the study published in 2004.

In a subsequent 2014 study, Peter Stott and two of his colleagues asked how much the probability of a similar event occurring had changed ten years after 2003.The result was that global warming, meanwhile, had increased the odds by about 10 times.A heat wave that would once have occurred every 50 years at that point had become an event with a return period of 5 years.

The extreme heat of 2003 showed the dramatic nature of the impacts of such a phenomenon.A study published in 2016 calculated that in the summer of 2003, climate change increased the risk of heat-related mortality in central Paris by about 70% and by about 20% in London, where maximum temperatures had been lower.The authors of an article, published in 2021 on Nature Climate Change, used data from 732 locations in 43 countries to estimate the mortality burden associated with heat exposure between 1991 and 2018.Their conclusion was this:“Across all countries examined in the study we find that 37% of heat-related deaths can be attributed to anthropogenic climate change and that increased mortality is evident on every continent.”

Since 2003 the science of attribution has made significant progress.Several recent heat waves have represented an opportunity to highlight, and confirm, the contribution of global warming to the increase in the probability and intensity of these phenomena.During the one that occurred in Siberia in 2020, the record temperature of 38 °C in the city of Verkhoyansk.The heat has facilitated the spread of large fires in forests and the acceleration of the melting of permafrost, which has even caused damage to buildings.The title of the attribution analysis published in 2021 in the journal Climate Change it is eloquent:«the prolonged heat that hit Siberia would have been «almost impossible without anthropogenic influence»

The 2021 heat wave in Western Canada and the northwestern United States:49.6 °C recorded in a Canadian village.The subsequent attribution study defined this event "virtually impossible" in the absence of global warming.In the same year, extreme heat also hit Europe.Near Syracuse, 48.8 °C were reached.The British Met Office analyzed this event, which constituted «another example of how climate change is making our weather extremes more severe», he stated one of the authors.

#IPCC #ClimateReport says #climatechange ⬆️ extreme weather
In the last 6 weeks alone, we have seen
🌡️record-breaking temperatures (49.6°C in Canada)
🔥raging wildfires in North America, Siberia and the Mediterranean
🌧️unprecedented rain and floods in Central Europe and China pic.twitter.com/xVyavgNVlv

— World Meteorological Organization (@WMO) August 10, 2021

The 2022 It's been another year of heat waves in Europe.The combination of high temperatures and lack of precipitation has led to a serious soil water deficit in the Po river basin and other areas.Droughts are too more likely, due to climate change.In the latest report of theIntergovernmental Panel on Climate Change (IPCC) states that «it is virtually certain that heat extremes have become more frequent and more intense in most regions of the earth since the 1950s.The IPCC states with “high confidence that anthropogenic climate change is the primary driver of these changes.Some recent warm extremes observed in the last decade would have been extremely unlikely without human influence on the climate system."

Even these days the deniers are busy doing what they do best:muddy the waters.There are those who, for example, remember the 40 °C in Rome, recorded in July 1983, as if that event demonstrated that heat waves like the current one are nothing new, as if it were proof that change climate is an invention.But it is not a temperature of a single location, in a single year, that proves or disproves climate change, it is a trend that we observe in the medium and long term and at a global level.As the IPCC writes, what is significant is the increasing frequency of high temperatures, even when they are not records.

In Hot Air, an essay published in 2021, Peter Stott tells the first-hand story of science's battle against climate denial.Deniers have promoted an ideology by passing it off as scientific skepticism.True skepticism is open to doubt, to critical examination of claims, and follows the evidence, rather than denying or manipulating it.The actions of denialist groups, often supported by the fossil fuel industry, they deceived public opinion and influenced the course of politics in key countries such as the United States.

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As Stott notes, “It has taken too long for governments to treat the climate crisis with the seriousness it requires.But now that progress is finally being made, it is crucial that these first steps do not falter.Meanwhile, the author observes, "the dark forces of denial remain at play."

The political parties most inclined to denialism are today trying to transform climate change into a cultural battle.Even when they do not outright deny climate change, their propaganda tactics aim to associate climate change issues with left-wing ideology.These parties treat the issue as if it were a fixation of environmentalists, extremists and fanatics, who want to destroy our economy and prosperity.Economy which, instead, it is threatened by climate change itself.In their speeches, climate and environmental policies become a worse problem than climate change itself.

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Thanks to this propaganda, facts disappear and only words and polemical tones, slogans and ideological enemies remain.If the facts disappear, it is as if no one ever discovered them.It's as if we never knew them, as if we were still completely ignorant.Denialism is also this:induced, interested and malicious ignorance.

We can only agree with Stott:“For the safety of humanity on Earth, we cannot afford to have more leaders promoting the false belief of climate denial.”

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