Climate change is the greatest health threat facing the world in the 21st century, according to major research unveiled by The Lancet.
Its study, The Lancet Countdown on health and climate change, says that rapidly increasing temperatures have exposed vulnerable populations, mainly adults older than 65 years and children under one year, to 3.7bn more heatwave days in 2021 than during 1986–2005.
Heat-related deaths increased by 68% between 2000–04 and 2017–21, a death toll that was significantly exacerbated by the COVID-19 pandemic. Simultaneously, the changing climate is propelling the spread of infectious diseases, putting populations at higher risk of emerging diseases and co-epidemics.
Coastal waters are becoming more suitable for the transmission of Vibrio pathogens, some strains of which cause cholera. Meanwhile, the number of months suitable for malaria transmission increased by 31.3% in highland areas of the Americas and 13.8% in highland areas of Africa between 1951–60 and 2012–21, and the likelihood of dengue transmission rose by 12% during the same period. The co-existence of dengue outbreaks with COVID-19 led to “aggravated pressure on health systems, misdiagnosis, and difficulties in management of both diseases” in many regions of South America, Asia and Africa, according to the study.
The economic losses from climate change impacts are also increasing pressure on families and economies that are already challenged by the COVID-19 pandemic and the international cost-of-living and energy crises, further undermining the socio-economic factors behind good health.
Heat exposure led to 470bn potential lost labour hours globally in 2021, with potential income losses equivalent to 0.72% of the global economic output. This increased to 5.6% of the GDP in countries with low Human Development Index (HDI) – a statistical composite index of life expectancy, education and per capita income indicators – where workers are most vulnerable to the effects of financial fluctuations.
Extreme weather events also caused damage worth US$253bn in 2021, particularly burdening people in low HDI countries in which almost none of the losses were insured.
The Lancet warns that every dimension of food security is affected by climate change, aggravating the impacts of other crises. Higher temperatures threaten crop yields directly, with 2020 maize growth seasons being on average nine days shorter, and winter wheat and spring wheat growth seasons being six days shorter, than in 1981–2010 globally.
In the 103 countries analysed, extreme heat was associated with 98 million more people reporting moderate to severe food insecurity in 2020 than annually during 1981–2010.
