Compound Extremes and Multi-dimensional Risk
Anthropogenic global warming has profoundly reshaped the intensity, frequency, spatial distribution, and destructive potential of extreme climate events. Compound events—where multiple climate or weather phenomena co-occur—can lead to significantly amplified impacts on both human and natural systems.
To quantify and better understand these risks in a warming climate, we develop advanced Bayesian-based, time-evolving, multi-dimensional risk frameworks. These frameworks are designed to analyze the dynamic escalation of risks associated with compound extremes by quantifying their underlying causal mechanisms, their responses to a nonstationary climate system, and the socio-economic consequences they produce. This approach enables us to assess the influence of climate change on a range of compound extremes, including simultaneous hot and dry years across critical global agricultural regions and the increasing risks of concurrent meteorological and hydrological droughts in the U.S.
Our ongoing research addresses the complex challenges posed by high-dimensional, temporally and spatially varying compound and cascading extremes. By focusing on their causality and attribution, we aim to enhance climate resilience through a deeper, more comprehensive understanding of the dynamic risks involved.
Risk of Compound meteorological and hydrological droughts in a changing climate
This study investigates the increasing risk of compound droughts, where both meteorological and hydrological droughts occur simultaneously, across the contiguous U.S. The research highlights a 10-20% increase in the risk of moderate and severe compound droughts, with an 8-12% rise for extreme events over recent decades. Using a bivariate GARCH model, the study also reveals that these compound droughts exhibit strong short-term memory, particularly in the western U.S., where meteorological droughts significantly influence the likelihood of prolonged and severe drought conditions. These findings provide essential insights for adaptive water resource management and long-term mitigation strategies in the face of a changing climate.
Link:https://www.sciencedirect.com/science/article/pii/S0022169423010715
Multi-dimensional Climate Risk in a Nonstationary World
This study introduces an advanced Bayesian framework to quantify the spatial and temporal co-occurrence of climate stressors, particularly the joint probability of warm and dry conditions, in the context of a nonstationary, human-driven climate. We found that, due to anthropogenic climate change, the likelihood of simultaneous warm and dry years has doubled globally compared to the 1961–1990 baseline. This elevated risk is especially significant in key global agricultural regions, where extreme heat and drought are increasingly linked to human activities.
Our research also highlights that ambitious climate actions, such as adherence to the Paris Agreement, can significantly mitigate these growing risks by reducing the probability of extreme events occurring simultaneously across multiple regions. This multidimensional risk assessment offers critical insights for sectors such as water resource management and energy, which have traditionally relied on historical climate patterns for resource planning.
By developing this methodology, we provide a valuable tool for assessing and managing the complex multi-dimensional risks associated with a warming and nonstationary climate.
Link:https://www.science.org/doi/epdf/10.1126/sciadv.aau3487