How Climate Change Is Shifting Malaria Risk for African Children

Malaria is one of the world's deadliest diseases, and it is very sensitive to temperature. Scientists have now completed the biggest study ever done on how climate change affects malaria in Africa. Their findings show that rising temperatures caused by human activity have already changed where and how much malaria spreads — and that those changes will keep growing in the decades ahead.

Malaria is spread by mosquitoes that carry a tiny parasite called Plasmodium falciparum. These mosquitoes thrive best when temperatures are around 25 degrees Celsius. When it gets too cold or too hot, the mosquitoes and the parasites struggle to survive. That means temperature plays a huge role in where malaria can spread.

Researchers looked at more than 50,000 surveys of malaria rates in children ages 2 to 10 across the African continent. The data stretched over more than a hundred years, from 1900 to 2016. By comparing real climate data with computer simulations of a world without human-caused warming, the scientists could measure exactly how much climate change has affected malaria.

The study found that across Africa as a whole, climate change has caused a small increase in malaria cases. The average rise was tiny — about seven extra cases per 100,000 children. But the effects were very different depending on where in Africa you look.

In southern Africa and in the highlands of East Africa, places like Ethiopia and Kenya, temperatures used to be too cool for malaria to spread easily. As those areas have warmed up, malaria has moved in. Scientists found there was a 91 percent chance that climate change had increased malaria in southern Africa and an 84 percent chance it had done so in high-altitude East Africa.

The situation is different in West Africa and central Africa, where most malaria cases currently happen. Those regions are already very warm — sometimes too warm for the malaria parasite to survive well. As temperatures keep rising, conditions there are actually becoming worse for the mosquitoes. That means climate change could end up reducing malaria in those areas over time.

Looking into the future, the scientists made projections for different levels of greenhouse gas emissions. Even in a low-emissions future where the world limits warming to under 2 degrees Celsius, the overall rate of malaria across Africa is expected to start going down by the middle of this century. In a high-emissions future, malaria in West Africa could drop by up to 4.5 percentage points by the year 2100 — a very large change.

However, the cooler highland areas of East Africa and parts of southern Africa would still face more malaria, not less, in most future scenarios. Some areas could see malaria rates rise by 5 percent or more. Cutting greenhouse gas emissions could help protect those communities by preventing the worst temperature increases.

The good news is that human efforts to fight malaria have had a much bigger impact than climate change. Programs that handed out mosquito nets, sprayed for mosquitoes, and provided medicine helped cut the average malaria rate across Africa from about 40 percent in the early 1900s to about 24 percent by 2010–2015. That is a drop of 16 percentage points — far larger than any climate-related change found in the study.

Scientists also pointed to exciting new tools in the fight against malaria. New vaccines, including one called R21, could prevent between one-third and one-half of all malaria cases in young children. The researchers say that with good coverage of vaccines, bed nets, medicine, and insecticide spraying, it may be possible to nearly eliminate malaria in Africa by 2050.

But there are serious concerns as well. Funding for global health programs is shrinking, which could set back progress. A new type of mosquito called Anopheles stephensi, which can survive in cities and spread malaria at even higher temperatures, has been showing up in parts of East Africa. If it spreads widely, it could make climate change an even bigger threat than this study suggests.

The scientists say their findings bring new clarity to a debate that has gone on for decades. Climate change is not the biggest driver of malaria trends, but it is making things worse in some places and better in others. They urge governments to keep investing in malaria prevention while also working to reduce greenhouse gas emissions — because both fights are connected.