Geoengineering climate change could increase malaria risk for one billion people

Climate change is here to stay unless there is a joint, global effort to stop it. But as it turns out, not all efforts to cool the Earth’s sweltering temperatures are created equal. Some can actually harm large amounts of the world’s population in unforeseen ways.

In a new study published Wednesday in the journal Nature Communications, an international team of researchers has found that while geoengineering – a colloquial term for the use of new technologies and strategies to deliberately manipulate the planet’s environment – has could cool the planet, these approaches risk allowing the malaria parasite to spread and put a billion people around the world at risk. This is the first study of its kind to look at what will happen to public health if geoengineering is deployed at scale — and offers cautionary warnings against its use. emerging technologies to address the planet’s climate change problems.

Traditionally, two techniques form the core of geoengineering: removing carbon dioxide from the atmosphere to reduce its role as a greenhouse gas; and solar radiation management (SRM), in which particles are injected into the sky to shield the Earth from the sun and help the planet cool. Decarbonization is seen as the more pragmatic and rational option, while SRM is speculative and may create more climate problems than it can solve.

Colin Carlson, an environmental scientist at Georgetown University Medical Center who led the study, told The Daily Beast.

“The optimal temperature for malaria is 25 degrees [Celsius], “I said. “So if you do it like this [geoengineering] indiscriminately trying to bring the temperature down without really thinking about doing it carefully, you can essentially cool the tropics more than you intended and more than today “.

Carlson and his team found that indeed it seems to be the case. They used computer modeling to simulate two future scenarios for Earth’s climate with moderate or high levels of global warming. Both scenarios are run test in which SRM is implemented or not.

In a scenario where global warming is high and SRM strategies are deployed, about a billion more people are at risk of malaria — possibly because of this extreme lower temperature that the parasite prefers. .

Curiously, the risk of contracting a communicable disease (spread by infected mosquitoes) in these scenarios varies from region to region. For example, simulations show that SRM can significantly reduce the risk of malaria in the Indian subcontinent, but in Southeast Asian countries the risk is increased. In computer models with moderate global warming but no SRM, the increased risk of malaria moved from West Africa to East Africa. But if you throw in the SRM, this risk is completely reversed.

“There are strange nuances layered on top of biology, explaining that the risk of malaria is not exactly one but depends on different factors, such as how different types of malaria occur,” says Carlson. There are different optimal temperatures or effects of population density in a region.

This does not mean that it is certain that one billion people will get malaria if we decide to continue to develop geoengineering technology. What it urges is a risk-benefit analysis of whether the health risks of an overheated planet outweigh that of a colder planet that could allow infectious diseases to flourish.

“What were we trying to do with research? [is show] There’s a systematic way we think about infectious disease and climate, says Carlson. “We have the tools, we have the models, we have a method, and this is what the process looks like. We have to do the math. If the math leans towards geoengineering, then great. But we cannot just assume this addresses the health impacts of climate change.”

If geoengineering methods such as SRM are put to work, Carlson hopes we will begin to predict and prepare now for any inevitable health crisis, ensuring a supply and allocate life-saving treatments to areas affected by malaria and other infectious diseases such as dengue. , Ebola Virus, and even COVID-19.

“The core message here is that a world is too hot because malaria is not a world we can live in,” he said. “We know what our climate exercise is — we have to stop greenhouse gas emissions — but if we can fund the science and fund local health authorities to planning for some of these unusual situations, I think that helps a lot with long runs.”