Dr. Madeleine Thomson on Bridging the Gap Between Climate Projections and Public Health Decisions
When Paris prepared to host the Olympic Games in summer 2024, the organizing committee faced an unusual challenge. Among their top health concerns were two diseases: Covid-19, which Europe knew well, and dengue fever—a mosquito-borne illness traditionally associated with tropical climates, not the City of Light.
The reason for their concern? Warming temperatures had made dengue a credible threat in France. But when public health officials asked climate scientists for guidance on what to expect, they encountered a frustrating disconnect. Climate models could tell them with reasonable confidence what Paris might look like in 2075 or 2100. What they needed to know was what to prepare for that summer, and the summers that would follow.
This gap between what climate science can confidently predict and what health decision-makers urgently need represents one of the most critical challenges in preparing for climate-driven health threats.
When Timeframes Don’t Match
“Climate scientists have to be interested in how their science can benefit society in a practical way,” says Dr. Madeleine Thomson, Head of Climate Impacts & Adaptation at Wellcome. “Then they have to really look at the timeframe of decisions.”
Thomson has spent over 25 years working at the intersection of climate science and public health. As former director of the WHO Collaborating Centre on Early Warning Systems for Malaria and Other Climate Sensitive Diseases at Columbia University, she’s witnessed this communication breakdown repeatedly.
The problem is structural. Climate scientists have gotten remarkably good at projecting long-term trends. They can tell you with increasing precision how much the planet will warm by 2100 under different emissions scenarios, and which regions will see the most dramatic changes over the coming decades.
But ask them what will happen in the next five to fifteen years—the exact timeframe when health ministries need to build capacity, allocate budgets, and implement interventions—and the picture becomes much murkier.
“While likely changes in 50 or 100 years’ time are well-understood for some regions, making predictions for the next 5 to 15 years is very difficult,” Thomson explains. “And this is the timeframe often requested by decision makers.”
What Health Workers Actually Need
Consider a malaria control officer in eastern Africa. They’re not asking abstract questions about climate change. They need to know: Should we stockpile more mosquito nets this year? Will we need to expand our spray zones? Should we hire additional field workers?
These decisions require investment, training, and infrastructure that can’t materialize overnight. They need actionable information on a timeline that aligns with budget cycles, training programs, and procurement processes.
“People are often asked questions around climate change, but if you are down in the weeds as a malaria, dengue or Zika control person, you are really largely dealing in the timeframe of climate variability,” Thomson notes. “What is happening now? What happened last year? What might happen next year in this particular locality?”
The challenge is compounded by climate variability—natural fluctuations like El Niño and La Niña that significantly impact regional weather patterns in the short term. These variations interact with longer-term climate trends in ways that make near-term predictions particularly difficult.
In Pakistan, for example, increasingly intense monsoons linked to climate change have created devastating floods. When floodwaters recede, they leave stagnant pools—perfect breeding grounds for mosquitoes. Malaria cases jumped from 500,000 in 2021 to 1.3 million by 2024, with cases likely still rising. But predicting which specific districts will flood most severely in any given year remains extraordinarily challenging.
The Consequences of Miscommunication
This timeframe mismatch has real consequences. Health systems can’t prepare for threats they can’t anticipate. Resources get misallocated. Interventions arrive too late or in the wrong places.
Thomson and her colleagues at Wellcome are funding 24 research teams across 12 countries to develop digital tools that better integrate climate data with health information. One example: a research team in Vietnam is developing E-DENGUE, a tool designed to predict dengue outbreaks up to two months in advance specifically for the Mekong Delta region.
Two months may not sound like much, but it’s enough time to mobilize resources and concentrate interventions in areas most likely to be affected. This kind of actionable, near-term forecasting represents exactly the sweet spot health decision-makers need.
Speaking Across Disciplines
Part of the solution involves training on both sides. Thomson advocates for incorporating basic climate and environmental science into standard epidemiological training worldwide.
“I would incorporate some fairly straightforward information on climate and environmental disease drivers in all epidemiological training that happens around the world,” she says. “Outbreak response people can work with partners in countries to get the best data, but if the health sector doesn’t understand the issues, particularly around climate variability and change, then it’s very hard for them to use the information effectively.”
Similarly, climate scientists need to understand the practical constraints and decision timeframes of public health work. A perfectly accurate 50-year projection is useless to someone planning next year’s disease surveillance program.
The good news is that both fields are recognizing this disconnect. “You need climate scientists who are able to support decision makers across a range of time and spatial scales,” Thomson emphasizes.
Beyond Temperature: The Complexity Factor
The timeframe challenge is further complicated by the sheer number of factors that influence disease transmission. Temperature is crucial—it affects how quickly mosquitoes and pathogens develop and how frequently mosquitoes bite. But rainfall creates breeding sites. Urbanization changes mosquito habitats. Population movement spreads diseases to new areas. Land use changes alter ecosystems.
“We have to look at climate change in the context of all the other changes that are going on,” Thomson points out. “Yes, it will have an effect, but the key question is how important that effect will be relative to other things that are happening.”
This complexity means that even when climate projections improve for the 5-15 year timeframe, they’ll need to be integrated with data on demographics, land use, infrastructure, and healthcare capacity to be truly useful for health planning.
Building Better Bridges
The path forward requires sustained collaboration. Climate scientists and health professionals need to work together from the beginning of research projects, not just at the end when it’s time to “translate” findings.
This means climate scientists designing studies with practical decision timeframes in mind. It means public health officials articulating their specific information needs clearly. And it means creating institutional structures—like the WHO Collaborating Centres that Thomson has worked with—that facilitate ongoing dialogue.
As climate change accelerates, the stakes for getting this right only increase. Highland areas of eastern Africa and Latin America that were once too cool for dengue or malaria transmission are becoming vulnerable as temperatures rise. Europe is seeing tropical diseases establish footholds for the first time. Lyme disease is spreading into the Arctic.
“We have to expect more of this type of emergence: new diseases that were historically isolated which can spread very rapidly and have a huge impact,” Thomson warns. “We need to prepare ourselves to be able to respond rapidly to a broad range of possible threats.”
That preparation requires climate scientists and health workers who can speak the same language—and more importantly, who understand each other’s timeframes, constraints, and needs. The 5-15 year problem won’t solve itself, but recognizing it is the first step toward building the bridges we desperately need.