When Paris hosted the Olympic Games in summer 2024, organizers monitored two primary health threats: Covid-19 and dengue fever—a mosquito-borne illness traditionally associated with tropical climates, not France. Warming temperatures had made dengue a credible threat in the City of Light.

But when public health officials asked climate scientists what to expect, they encountered a frustrating disconnect. Climate models could confidently project what Paris might look like in 2075 or 2100. What officials needed was actionable information for that summer and the summers that would follow.

“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 witnessed this breakdown repeatedly during her 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 understands both perspectives.

The problem is structural. Climate scientists excel at long-term projections but struggle with the 5-15 year timeframe that health ministries need for building capacity, allocating budgets, and implementing interventions. Natural climate variability like El Niño and La Niña interacts with long-term trends in ways that make near-term predictions particularly difficult.

“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.”

This gap has real consequences: health systems can’t prepare for threats they can’t anticipate, resources get misallocated, and interventions arrive too late or in the wrong places.