Downtown Valencia during a heat wave this summer. (Source: Shutterstock)

Marcel Crok
Date: 28 October 2026

The height of the bar indicates the total number of heat-related deaths, and the red colour represents the proportion that, according to the researchers, is attributable to climate change.

Summer is over, so it seems logical that we can now take stock. The deaths have been counted. Or have they? Here is how the Dutch newspaper NRC describes the study:

“The summer of 2026 was probably the deadliest in Europe to date due to its high temperatures. That is the conclusion reached by scientists from Imperial College London and the London School of Hygiene and Tropical Medicine, based on an analysis of deaths resulting from the heat. According to the researchers, far more people died from the heat last summer than in the previous record years of 2022 and 2003.

The scientists estimate that during the hot months of June, July and August, there were more than 50,000 additional deaths due to the extreme weather. In reaching this conclusion, they drew on data from 854 European cities in thirty different countries, home to a total of 40 per cent of the continent’s population.”

Read the passages I’ve highlighted in bold carefully once more: “An analysis of deaths”, “they drew on data from 854 European cities”. This reads as though: the death certificates have been studied, the figures have been tallied. Nothing could be further from the truth. The published study is based on zero mortality data from 2026. You read that correctly: zero. As the American researcher Willis Eschenbach wryly remarked in an article about the study: it seems that using actual facts is soooo 20th century.

If no mortality figures from 2026 have been used, how do the researchers arrive at their estimate of 50,391 (yes, that ‘exact’ figure is mentioned in the study) heat-related deaths? They use historical temperature-mortality relationships and apply them to this summer.

Here, step by step, is what the researchers did:

1. They derived statistical correlations between temperature and mortality based on historical data (2000–2019) from 232 European cities.
2. These relationships were extrapolated to 622 other European cities for which no data were available. This brings the total to 854 ‘studied’ cities.
3. The temperatures in those cities in 2026 were analysed. Using climate models, an estimate was made of the proportion of the warming caused by climate change (i.e. by CO2).
4. Next, subtract the ‘human contribution’ from this summer’s temperatures to create a hypothetical cooler summer without climate change.
5. You now apply the temperature–mortality relationships identified in the past to ‘both’ 2026 summers and subtract the results from one another. This gives you the total heat-related deaths in 2026 and the contributions to this from the natural background climate (pink in the NOS graph) and the additional contribution from human-induced climate change (red in the NOS graph).

Bang, and you’re done. Suddenly, you’ve ‘proven’ – and published in one of the Nature journals – that 2026 was the deadliest heatwave year. Without even needing the actual mortality figures for that summer. Journalists won’t read the study anyway (see the extract from NRC) or won’t understand what tricks you’ve been up to. Media attention guaranteed. And critical comments such as this article and that by Willis Eschenbach won’t reach the masses. Mission accomplished.

More elderly people

Of course, there’s a quagmire of assumptions behind the study. But who’s going to quibble about that? Let’s name a few anyway. The study uses temperature-mortality relationships from the period 2000–2019 and assumes that these correlations remain constant thereafter. Why would that be the case? If summers are getting hotter and hotter, it stands to reason that more people would install air conditioning or that countries would draw up and implement heatwave plans, wouldn’t they? The study takes no account of this. Another study – albeit also based on model estimates (so caution is advised) – suggests that heat-related deaths would have been 80 per cent higher without adaptation. This indicates that it is a factor to be taken into account, something which was not done in the current study.

The researchers use data from just 232 cities and apply it, without any checks, to 622 other cities. Not all cities are the same, are they? One city might be much greener than another, making the heat more bearable.

But probably the most important factor is age. Whilst the researchers do use different age groups, the distribution across those groups for the period 2000–2019 is kept constant. Yet a significant shift has occurred during that period: Europe is ageing. Here is a comparison between 2000 and 2026:

The proportion of people aged 65 and over and those aged 80 and over has risen sharply. Older people (aged 80 and over) in particular are especially vulnerable to heat. The Danish environmental economist Bjorn Lomborg had already pointed this out earlier in the year when The Lancet published alarming figures on heat-related deaths in Europe. Lomborg described it on X as “textbook climate deception”. According to him, virtually the entire increase in heat-related deaths can be explained by the ageing population:

Source: Lomborg

When adjusted for age, Lomborg finds only a minimal increase in heat-related deaths:

Source: Lomborg

Cold is far more dangerous

The other, equally important point that Lomborg consistently makes, is that the obsession with heat is misplaced because, worldwide and in Europe too, cold still claims far more victims than heat. Whilst global warming in Europe will indeed lead to (slightly) more heat-related deaths, the reduction in the number of cold-related deaths is much greater. This is therefore good news overall, which is never highlighted when the focus is solely on heat.

Remarkably, the Dutch National Institute for Public Health and the Environment (RIVM) published a study last week which confirmed this ratio for the Netherlands as well. According to RIVM, there are around 350 additional deaths from heat each year, compared with no fewer than 12,000 (!) deaths from cold. Thirty-five times as many!

Naturally – one might almost say – NRC focused on the heat in an article on the subject (“People in some neighbourhoods are more resilient to heat than in others”). But columnist Marianne Zwagerman was quick to point out, in De Telegraaf, the large number of cold-related deaths reported by RIVM. She concludes: “We combat the heat, but let thousands of Dutch people die from the cold.”

One of the researchers involved in the RIVM study is Hein Daanen from VU University Amsterdam. Coincidentally, I heard him explaining on the radio this summer why older people actually die more quickly from heat than younger people. In the clip, however, Daanen also highlighted the far greater danger posed by the cold and noted that it is strange that the Netherlands has a National Heat Plan but no National Cold Plan.

This article was originally published in Dutch on Indepen.eu on 27 October 2026

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