Ross Clark

Are heat deaths on the rise?

Are heat deaths on the rise?
(Photo credit should read DANIEL LEAL-OLIVAS/AFP via Getty Images)
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As a case study of how assertion can end up sounding like fact, I thoroughly recommend the Lancet’s report this morning claiming that the number of heat-related deaths globally has more than doubled in the past 20 years — and in particular the reporting of the story on the Today programme this morning. The message of the BBC report could not have been clearer: climate change is killing us at alarming speed and we’d better do something about it quick. 'Research suggests that the number of older people dying from heat-related causes has more than doubled in the UK since the early 2000s,' it began (01:05:55). 'The report published in the Lancet tracks the links between climate change and health. It says there were an estimated 8,500 such deaths recorded among the over-65s in 2018… Medical experts say the failure to tackle the health impact of climate change is putting lives at risk.' 

What the BBC report did not spell out, and for which you have to go the Lancet to find out, is that these supposed 8,500 deaths have not actually been recorded by anyone. The Lancet has arrived that that figure by estimating the number of people it thinks ought to have died from heat in 2018, based on the number of over-65s and the meteorological conditions to which they were exposed.    

If you want a real guide to the number of elderly people who actually did die from the heat in 2018 you can go to the Office of National Statistics (ONS). The summer of 2018, as it happens, did have a heatwave which caused a spike in deaths, but nothing on the scale of the Lancet guesstimate. In August 2018, the ONS put out a note showing that between 1 June and 20 July — which covers the whole period of the heatwave — there were 995 deaths above the five year average for those weeks (there was a milder July heatwave in July 2013 but no such prolonged heatwaves during the years 2014-2017). 

As the ONS explains, it is not possible to say exactly how many of these deaths really were down to the heat, but how on Earth can the Lancet justify a claim that more than eight times this number of people were killed off by the heat? 

A far bigger killer in 2018, remarked the ONS, was the cold. This was the year of the ‘beast from the east’ when Siberian winds struck the country in early March. Between 3 February and 23 March, there were 8,883 excess deaths compared with the five year average for that period. Heat kills, even in a temperate country like Britain, but nothing like cold does. Deaths from the cold have, as it happens, fallen sharply in recent decades. Excess winter deaths (the additional number of deaths in winter months relative to non-winter months) fell from 106,000 in 1950-51 to 23,200 in 2018-19, in spite of a growing population. This fall is not just a function of the climate, of course. A large part of it will be down to clean air legislation, better treatment of respiratory diseases and so on. But it stands to reason that if winters are to become milder we can expect fewer deaths from the cold. 

The Lancet’s figures for the number of people supposedly being bumped off by heatwaves in Britain was part of a global estimate. Worldwide, claims the journal in its annual Countdown on Health and Climate Change, there was an average of 296,000 deaths among the over-65s caused by heat over the years 2014-2018, an increase of 53.7 per cent on the period 2000-04. Again, these are not deaths that have actually been recorded — it is simply an estimate of the number of people the Lancet thinks might have died due to the heat, based on the population and the meteorological conditions to which they were exposed.

A 53 per cent rise in over 65s dying of the heat? That sounds quite frightening until you realise that the main reason for this is population. According to the World Bank, the number of over-65s in the world grew from 420 million in 2000 to 673 million in 2018 — an increase of 60 per cent. In other words, the main reason there are more over-65s vulnerable to heatwaves is because there are more over-65s. The real story here is the increase in global population and longevity. Any impact that climate change is having on our health is dwarfed by the fact that more of us are living to a good age thanks to falling infant mortality, better diet, healthcare and so on. Yet instead of celebrating this good news, we get fed endless scare stories about theoretical death tolls from climate change.