The links between climate change and pandemics remain among the least studied and least visible of the effects of climate change on human health. While climate-related effects on vector-borne diseases such as malaria, dengue, and Zika have received attention, there is a significant gap in understanding how climate change influences spill over of viral pathogens most likely to trigger pandemics. Our proposed research will address this critical evidence gap by analyzing existing data and new data we will collect to examine climate as a driver of spillover for pandemic-potential viruses. 

Nearly all pandemics in the past 100 years started with zoonotic spillover events, with most arising directly or indirectly from wildlife hosts. Recent studies emphasize that land-use changes, especially deforestation, increase zoonotic spillover risk. However, preliminary evidence, including our previous landmark studies, indicates that climate change intensifies every step of the spillover cascade. This project aims to systematically investigate interactions among climate change, bats, pandemic-potential viruses, and humans across three case studies in varied geographic contexts, building a broad framework to improve spillover prediction strategies. 

Bats may account for the majority of projected novel virus sharing due to climate-driven range shifts, and bats host four of the nine diseases the World Health Organization prioritizes for research, including Ebola, Marburg, coronaviruses, and Nipah virus. Bats’ high metabolic demands, climate-sensitive physiology, and dependence on climate-driven food resources make them ideal for studying climate impacts on viral dynamics. Using bats as a model, we will focus on two primary hypotheses tested through case studies in South Africa, Australia, and the US-Mexico interface. Aim 1 will test the hypothesis that climate influences spill over risk by altering bat distribution and therefore overlap with humans and by influencing the cumulative physiological, nutritional, and energetic stress (allostatic load) experienced by bats that determines their susceptibility to viral infection and shedding. Aim 2 will test the hypothesis that climate change will increase spillover risk by exacerbating the key mechanisms described in Aim 1: increasing overlap of bats and humans and increasing allostatic load in bats, thus raising the risk of spillover to humans. 

Our methodology combines long-term environmental, virological, and ecological data with Bayesian network models to capture climate-spillover relationships and simulate the potential impacts of climate change on spillover risk. We will quantify mechanistic links between climate factors, bat behavior, and spillover risk variables. 

This research will inform policy makers and other researchers, providing actionable insights to prevent future outbreaks, shifting the focus from pandemic containment to prevention.