In the summer of 2023, the world recorded the highest temperature in 100,000 years. All continents were affected and even the gentle breeze often felt in the tropics did little to cool the sweltering heat experienced by small island developing states (Sids). Our latest Lancet Countdown report, tracking the connections between health and the climate crisis, showed that Sids experienced 103 health-threatening heat days each year between 2018 and 2022 – equating to almost a third of the year being above the threshold whereby heat-related deaths are likely to increase.
Aside from the direct dangers of exposure to health-threatening heat such as heat stress, heatstroke, and, in severe circumstances, death, increased heat improves the climate suitability for the spread of infectious diseases such as dengue fever, malaria and vibrio by expanding their climatic boundaries, our most recent data shows. Our mathematical models of dengue fever show an increase in the frequency of outbreaks with an increase in heat, and the evidence suggests that the climate crisis has exacerbated the frequency of these outbreaks.
