It is therefore a declared methodological approach, supported by scientific research criteria (mathematical models, statistics, etc.).
The scientific network that makes up the WWA (so not just one or two climatologists) assesses the link between extreme weather events and climate change and concludes that, in the specific case of China, ‘climate change made the heatwave at least 50 times more likely”.
In general, according to the WWA, climate change, caused by human-produced greenhouse gas emissions, ‘has made heatwaves hotter, longer and more frequent’. Future ones ‘will be even more intense and more frequent if emissions are not reduced rapidly’, according to the researchers.
The WWA’s thesis does not deny that natural phenomena such as anticyclones or El Niño may help trigger these heatwaves. However, ‘the rise in global temperatures due to the burning of fossil fuels is the main reason why they are so severe’.
On what scientific basis did the researchers reach these conclusions?
By using historical weather data and climate models, and by comparing today’s weather and climate data with those of the past.
The present-day periods examined by the WWA are deliberately the most recent ones, in which the heat was ‘most dangerous’: 12 to 18 July in southern Europe, 1 to 18 July in the western United States, Texas and northern Mexico, and 5 to 18 July in central and eastern China.
The data showed an increase in the intensity of temperatures within the heatwaves themselves: according to the WWA, they are 2.5 degrees hotter in Europe, 2 degrees in North America and 1 degree in China.
The second finding is that, while in the past these events were to be considered exceptional (‘abnormal’ is the term used), in today’s climate they can occur roughly every 15 years in North America, every 10 years in southern Europe and every 5 years in China.
This time span is set to shrink, so heatwaves ‘will become even more frequent and occur every two to five years’ if global warming reaches 2 degrees, ‘which could happen in about thirty years’.
The objections
And now to the objections, some of them expressed violently, to these findings.
The main criticism concerns the speed with which they were produced and published. In essence, the accusation is that they did not go through the long process of specialist journals, which usually ‘legitimise’ a scientific study by publishing it (after an indeterminate length of time).
The WWA scientists’ answer is that the methods used in the research are all widely approved by the vast majority of the international scientific community.
The second criticism, linked to the first, is that the WWA is a panel of scholars ‘leaning’ towards environmentalism and therefore with preconceived views.
In fact, the WWA has more than once shown caution about possible ‘ideological’ influence on its studies. The most recent time was precisely over the floods that struck Emilia-Romagna in May.
In that case, the WWA published, as quickly as its method allows, the results of an attribution study on the specific links between the floods in Romagna and climate change. It found none.
So the supposed ‘environmentalists’ of the WWA certified on that occasion – after a statistical analysis of past data and through computational climate simulations – that global warming was to be ruled out among the causes of the flooding, which were not made more likely by the increased concentration of greenhouse gases in the atmosphere produced by human activity.
Indeed, on that very occasion climate physicist Davide Faranda, a researcher at the Laboratory of Climate and Environmental Sciences (LSCE) of the Pierre Simon Laplace Institute and a member of the WWA, had stated plainly: ‘I want to give the most truthful message possible. I am not an environmental activist but a scientist, and I want to give the correct message.’
He added that he did not want the message about the floods not being attributable to global warming to be used ‘by climate change sceptics to talk rubbish’.
It could hardly be clearer…
