In a warming world, extreme heat will become more frequent, and more extreme, leading to potentially devastating socioeconomic and ecological damages. Beyond maximum peak temperatures, the complex interplay of additional factors such as humidity, lack of nighttime cooling, and prolonged drought can lead to compounding risks and increased impacts. When unprecedented record-shattering compound heat stress extremes occur, it raises the question of whether the current tools of the climate community such as climate models are sufficient to capture the risk and intensity of rare but plausible devastating extremes under present, and especially future climate conditions. Are climate model projections downplaying the risk and intensity of current and future extreme compound heat stress due to missing or incorrect process representation? Can we sufficiently sample the most unlikely and extreme albeit still plausible events? And how does low-probability, high-impact extreme compound heat stress develop, which intensity, persistence, compounding or level of impact could it reach?
As we strive to adapt to a warming planet, it is imperative to comprehend the full extent of these compound heat stress events and their potential societal, economical and ecological impact. The primary goal of TrueHeat is to unravel the intricate dynamics of the most rare but physically plausible extreme compound heat stress and its drivers and impacts in present and future climates. The project is structured in a three-tier approach to address these critical questions.
1. Curating Best-Estimate Heat Projections: We will exploit the growing number of large ensembles from single climate models to develop refined future heat projections. These projections will incorporate state-of-the-art evaluation techniques, enabling us to enhance our understanding of how extreme heat events might unfold under different climate scenarios according the models that best represent real-world climate conditions. By combining these projections with up-to-date epidemiological data and models, we aim to assess the potential impact of heat stress on human health, providing valuable insights into the near-term mortality risks associated with extreme heat.
2. Investigating Current Climate Variability: We will use climate prediction data to identify where in the world to assess where the chaos in the climate system could produce the largest heat stress intensification already under our current climate, while determining what leads to forecasted instances of extreme unprecedented heat to not occur, or occur in a less extreme form in reality.
3. Sampling Clustering Heat Stress: Employing an innovative ensemble boosting technique, we will generate sets of simulations that deliberately explore the most extreme but physically plausible worst-case heat clustering events, where extreme heat occurs repeatedly in a season or concurrently over several remote regions. This unique approach will enable us to quantify the variability in the characteristics of these clustering extreme heat stress events, assessing their potential short- and long-term driving factors.
This project will yield the best-informed knowledge of the unlikely but physically plausible heat that we may come to experience in the near-term future, determining how instances of extreme compound heat can turn into their most impactful and unprecedented version. This newfound knowledge will offer crucial insights for policymakers, urban planners, public health officials, and disaster management teams, enabling them to formulate more effective strategies to mitigate the adverse effects of extreme heat events. This project's outcomes are poised to provide a comprehensive view of the risks posed by extreme compound heat stress, shedding light on both their driving mechanisms in a changing climate and their potential implications for human well-being, ecosystem health, and socioeconomic stability. With these insights, we can make informed decisions to better prepare for the challenges presented by a rapidly changing climate, ultimately safeguarding our planet and its inhabitants for generations to come.
