In my previous post here, I looked at the central claim in the Lancet’s Countdown report, that “Heat-related deaths reached a record-high of 710 000 estimated deaths globally in 2023, of which 71·5% [507,650] can be attributed to climate change.” That claim simply didn’t stand up against the evidence provided by a more authoritative database of health metrics, despite the Lancet report citing it as a source of data. In this article, I’ll look at another claim from the report – that climate change is increasing the potential for infectious diseases to spread.
Aficionados of the climate wars will remember the climate-malaria link controversy of the 2000s. Despite alarmists’ insistence that climate change would increase the spread of malaria, sceptics of the claim noted documentary evidence that the disease had been endemic at very northern latitudes, including within the Arctic Circle. The idea of ‘tropical diseases’ being pushed northwards by a warming planet therefore suffered from a major category error. Moreover, the disease had been abolished in lower, but still categorically temperate, not ‘tropical’, latitudes by draining land and spraying insecticide – both of which are interventions that the green movement objects to. But even worse news for the alarmists was to come. Rates of malaria deaths began falling through the 2000s.
The Lancet Countdown has attempted to conceal this rate of progress by hiding behind a novel metric. Rather than looking at the number of cases of vector-borne diseases, it has developed a measure called ‘climate suitability’. Of particular interest to the report are dengue virus, chikungunya, Zika virus, West Nile virus and malaria.
It’s hard to understand why the report includes West Nile virus, as it admits that it “has a near-global distribution”. In Europe and the US, the virus is attributed to around 100 deaths in each, and though the distribution of cases in Europe is attributed to warming causing a northward migration, that pattern is not evident in the US, where counties in northern states between east and west such as Montana and North Dakota appear to have greater incidence rates than southern states in general, such as Florida or Texas.
Global mortality statistics from chikungunya and Zika are hard to find, because deaths from them are rare. Global annual recorded deaths from Zika are often as low as zero and have only exceeded single figures in one year according to the IHME GBD database. Deaths from chikungunya are usually in the low hundreds, and almost exclusively in vulnerable people.
