Climate change is driving a ‘shift’ in childhood malaria risk across Africa

Rising temperatures are redistributing the risk of childhood malaria in sub-Saharan Africa, resulting in areas of “new risk” in the east and south of the continent, but also “relief hotspots” in western Africa.

This is according to a new study, published in Nature, which provides the “most comprehensive look to date at the impact of climate change on any infectious disease”.

The research finds that since the year 1900, climate change has resulted in one extra case of malaria for every 1,000 children in sub-Saharan Africa on average. 

Over the 21st century, climate change is expected to drive down malaria rates across the continent on average, as temperatures rise above the optimum range for mosquitoes. 

However, the authors emphasise that continent-wide averages hide more detailed local trends. 

They find that cooler parts of Africa face an increase in malaria risk, as rising temperatures have made the regions more suitable for malaria-carrying mosquitoes, while warmer regions see a suppression in malaria cases.

The lead author tells Carbon Brief that this is the first study to use “attribution” – a field of climate science which uses models to compare conditions in a world with global warming to one without – to assess the impact of climate change on malaria.

The study also reveals that climate change is not the main driver of shifting malaria risk in Africa, with public health measures and government policy making a more significant impact.

The “most important” message from the study, according to another expert, is that to eliminate malaria entirely, “effective surveillance, prevention and treatment remain substantially more influential – and more actionable – than climate change alone”.

Childhood malaria

Malaria kills hundreds of thousands of people every year. The World Health Organization (WHO) estimates that 610,000 people died due to the disease in 2024.

The disease is transmitted to humans by bites from mosquitoes infected with the malaria parasite. Malaria spreads most rapidly in warm, wet regions, where the parasite-carrying mosquitoes can live and breed.

However, malaria is preventable. A total of 42 countries – mainly in Europe and the Americas – have eliminated the disease entirely through a combination of measures including insecticide use, draining the swamplands that provide breeding habitats for mosquitoes and improving basic healthcare services .Global mortality from malaria declined by 90% over the 20th century. 

Today, the vast majority of malaria cases are recorded in Africa, which was home to 95% of malaria cases and deaths in 2024. Children under the age of five make up three-quarters of all African malaria deaths.

The malaria-causing parasite can be detected using a blood test. Over the last century, scientists, government officials and healthcare professionals have collected thousands of blood samples from people across sub-Saharan Africa and tested for the presence of the malaria parasite.

In 2017, scientists brought together more than 50,000 samples collected from sub-Saharan Africa over 1900-2016. This data provides a “snapshot” of the amount of malaria in the population in any year in the last century the study explains.

Dr Colin Carlson is an assistant professor of epidemiology at the Yale school of public health and lead author of the study. He tells Carbon Brief that malaria in Africa is “extraordinarily well documented”, as a result of academic interest and colonial rule in the continent.

The size and quality of the malaria dataset are “exceptionally rare”, Carlson says. He explains that the dataset stretches back to before the impacts of human-caused climate change were strongly felt, making it “extraordinarily” valuable for this analysis. 

The chart below shows the percentage of children between two and 10 years old who tested positive for the malaria parasite over 1900-2016. Each dot indicates one blood test result and the pink vertical bars indicate periods of “successful malaria prevention intervention”, such as the 1955-69 global malaria eradication programme.

Attribution

The authors use the blood test survey data to develop a statistical model separating out the climatic, social and economic factors that affect malaria, such as temperature, rainfall, economic development, healthcare and population changes. This allows the authors to isolate the effects of the climate on malaria.

They find that malaria prevalence in children peaks when average monthly temperatures reach 24.9C, dropping off in warmer and cooler climates. 

Mosquitoes also need stagnant or slow-moving water in which to lay their eggs. The authors find that periods of drought tend to decrease malaria prevalence one-to-two months later, whereas floods increase prevalence two-to-three months later. However, they conclude that rainfall is “less important than temperature” in predicting malaria rates.

They then combine the statistical models with climate models, to simulate childhood malaria rates in a range of past and future climates. 

First, the authors simulate malaria rates in the present day, by running the models using the climate of 2000-14. They then carry out the same analysis, using the climate of a hypothetical world without human-caused climate change.

By comparing the two, the authors were able to attribute the impact of climate change on malaria rates across Africa.

The link between climate change and malaria in Africa is complex and “surprisingly contentious”, according to the authors. For example, they write that “malaria resurgence in the east African highlands became a particular point of contention, with over a dozen studies arguing for or against climate change as a substantial driver”.

It adds:

“Today, malaria experts generally agree that climate change has contributed to elevational shifts in malaria epidemics and the geographical ranges of mosquito vectors. However, the cumulative effect of climate change on the burden of malaria is still an open question.”

Lead author Carlson says this paper is “one of the first impact attributions on infectious disease” and the first attribution study on climate change and malaria. He adds:

“I think it’s the most clarity we’ve had on the malaria question.”

Dr Teresa Yamana, an associate research scientist at Columbia University, who was not involved in the study, praises its “rigorous” methodology. She tells Carbon Brief that the work “demonstrates the potential of climate attribution methods to quantify the impacts of climate change on infectious diseases”. 

Warming world

The findings show that “climate change isn’t just making malaria worse or better – it’s moving it, says study author Prof Tamma Carleton, an assistant professor at UC Berkeley:

“Whether a place sees elevated malaria risks or reduced burdens under climate change depends on how hot it is today. We see relief in the hotspots and new risk nearly everywhere else.”

For example, in the Ethiopian highlands, low temperatures – which are unsuitable for mosquitoes to live and breed – have historically limited the spread of malaria. However, the region has seen childhood malaria rates increase by more than eight cases per 1,000 children since the year 1900 as rising temperatures have allowed the insects to expand their habitat.

The authors also found a similar increase in malaria prevalence in cooler southern African countries.

In contrast, global warming is pushing average temperatures above the ideal range for mosquitoes in many hotter parts of Africa, driving down malaria rates. The authors find that in western Africa, climate change has caused a reduction of four malaria cases per 1,000 children per year by 2014, reducing prevalence by 1-2%.

Overall, climate change has resulted in one extra case of malaria for every 1,000 children in sub-Saharan Africa since the year 1900, the study says.

The authors also run their models for three future climate scenarios: low (SSP1-2.6), intermediate (SSP2-4.5) and very-high (SSP5-8.5) emissions pathways. Comparing these to the present-day model results shows how climate change could affect malaria cases over the coming century. 

They find that the trends observed so far will largely continue into the future – meaning climate change will lower the prevalence of malaria in warm regions and increase the prevalence in cool regions.

            <div class="gf_browser_unknown gform_wrapper gform-theme gform-theme--foundation gform-theme--framework gform-theme--orbital newsletter-inline_wrapper" data-form-theme="orbital" data-form-index="0"><div class="gform_anchor"></div>
                    <div class="gform_heading">
                        <p class="gform_description"></p>
                    </div>
                    <div class="gform-body gform_body"><div class="gform_fields top_label form_sublabel_above description_above validation_below"><div class="gfield gfield--type-honeypot gform_validation_container field_sublabel_above gfield--has-description field_description_above field_validation_below gfield_visibility_visible"><label class="gfield_label gform-field-label" for="input_5_7">LinkedIn</label><div class="gfield_description">This field is for validation purposes and should be left unchanged.</div><div class="ginput_container"></div></div><div class="gfield gfield--type-html gfield--input-type-html gfield--width-full preheader gfield_html gfield_html_formatted gfield_no_follows_desc field_sublabel_above gfield--no-description field_description_above field_validation_below gfield_visibility_visible">Free fortnightly newsletter