A day before the latest United Nations Climate Change Conference (COP27) began, a group of global experts convened by The Lancet published a report about the adverse health effects of climate change. Their conclusion was as jarring as it was straightforward: human health is at the mercy of fossil fuels.

Unfortunately, health remained at the bottom of the priority list at COP27. To be sure, some important health-focused conversations took place at the World Health Organisation’s side pavilion. These discussions were particularly timely, given the current surge of COVID-19, fuelled by the newest Omicron subvariants, in Europe and the United States. But, beyond a blink-and-you-miss-it mention in the preamble, the COP27 declaration makes no substantive mention of the climate-health nexus.

It is a glaring omission. The connection between climate and health is deep and multifaceted. Consider, for example, how warming temperatures and unprecedented flooding have encouraged the spread of mosquitoes, carriers of diseases like dengue fever, malaria and the Zika virus, well beyond their traditional breeding grounds. If nothing is done, Zika will threaten an additional 1.3 billion people by 2050, and dengue fever will affect a whopping 60 per cent of the world’s population by 2080.