Geoengineering is often framed as a tool for climate justice. Our study challenges that idea, showing that solar geoengineering would create regional tradeoffs and potentially increases in malaria risk worldwide.

Our study is the first to project the impacts of solar geoengineering - an emergency intervention to reduce the effects of global warming, in theory particularly for vulnerable frontline populations - on an infectious disease. We focus on malaria, which doesn’t increase linearly with temperature (i.e., warmer isn’t necessarily more malaria; cooler isn’t necessarily less).

In any scenario, geoengineering will probably shift malaria risk around continents, creating regional trade-offs in health outcomes within the Global South. But in the kind of extreme warming scenario where geoengineering might be most appealing, we find that deploying geoengineering would increase (or rather, reverse a decline of) malaria population at risk by roughly a billion people.

The study raises fairly major questions given that geoengineering is often framed around life-saving solutions for poor and vulnerable populations. The study was funded by a project called DECIMALS that revolves around projecting impacts of geoengineering on developing countries (and giving them more of a voice in the science - our project is a collaboration with icddr,b in Bangladesh and the Climate Risk Lab at the University of Cape Town), and highlights the need to bring the health sector into those conversations.

Carlson CJ, Colwell R, Hossain MS, Rahman MM, Robock A, Ryan SJ, et al. Nat Commun. 2022;13: 2150.