Case for and against geoengineering the climate

GEOENGINEERING the climate could have massive repercussions for the health of billions of people living in tropical countries with malaria, according to research by an international team including UCT researcher Dr Christopher Trisos.

Solar geoengineering – emergency proposals to inject aerosols into the stratosphere to increase the reflection of sunlight back to space to offset global warming – could produce large trade-offs in health risks among Global South countries that are often excluded from geoengineering conversations, Tritos said.

“The potential for geoengineering to reduce risks from climate change remains poorly understood, and it could introduce a range of new risks to people and ecosystems.”

The study focused specifically on the effects of solar geoengineering (also called solar radiation modification, or

SRM) on the occurrence of malaria. Mosquitoes that carry the disease are particularly sensitive to temperature.

Additionally, malaria’s burden is measurable enough in that it impacts economic growth and population-level mortality; if geoengineering is intended to reduce the health risks of climate change in developing countries, perhaps one of the greatest reductions could be experienced through impacts on malaria.

In the study, the researchers used climate models to simulate what malaria transmission could look like in two future scenarios, with medium or high levels of global warming, with and without geoengineering. The models identify which temperatures are most conducive for transmission by the Anopheles mosquito vectors, and identify how many people live in areas where transmission is possible. According to the research team’s simulations, proposed geoengineering schemes could lead to local benefits in east Africa, but also large adverse impacts on west Africa and southern Asia.

Assistant research professor Colin Carlson, from the Centre for Global Health Science and Security at Georgetown University Medical Centre, who led the study, elaborated: “One of the most surprising findings was the scale of potential trade-offs between regions. For example, in both scenarios, we found that geoengineering might substantially reduce malaria risk in the Indian subcontinent even compared to the present day. However, that protective effect would be offset with an increase in risk in southeast Asia. For decision-makers, this might complicate the geopolitical reality of climate intervention.”

Trisos said these scenarios illustrate that solar geoengineering could have adverse impacts on health in cases where the burden of infectious diseases does not strictly increase with warming temperatures.