Climate change is expected to lead to an increase in extreme winter storms with strong winds and heavy rainfall in the UK and Ireland, according to new research conducted by experts at Newcastle University and the Met Office. The study focused on compound wind-rain extremes, where extreme wind and rainfall occur simultaneously. Data from climate simulations for control and future periods showed that as the climate warms, these events are likely to become more severe, with stronger winds and heavier rainfall happening together. These changes are primarily driven by increased rainfall, as well as a strengthened jet stream and its southward displacement bringing storms through warmer areas.
The findings of the research, published in the journal Weather and Climate Extremes, suggest that the increase in intensity of these compound wind-rain extremes could lead to more frequent windstorms coinciding with extreme rainfall and floods. This poses challenges to coastal areas vulnerable to compound flooding, as well as emergency response resources due to larger aggregation of impacts to infrastructure such as electricity and rail networks. Lead author Dr Colin Manning emphasized the need for cutting greenhouse gas emissions and increasing infrastructure resilience to avoid the worst impacts of these compound extremes.
To analyze the compound wind-rain extremes and their future changes, the research team used event-based analysis based on the occurrence of extra-tropical cyclones over the UK and Ireland. They assessed the severity of these events using Wind Severity Index and Rainfall Severity Index, and estimated return periods for individual and joint extremes to determine their likelihood. The researchers also identified local co-occurrences of extreme wind gusts and rainfall to understand their changing intensity contributions in future climate simulations.
The study highlighted the importance of considering compounding effects, including the co-occurrence of different hazards and the clustering of extreme events, in fully capturing the potential impacts of climate change. Future research will need to include a wider range of climate models to determine the robustness of the results across different models. Understanding and quantifying the link between compound wind-rain extremes and their impacts will be crucial for stakeholders to better assess their risks and choose cost-effective adaptations to mitigate those risks.
The research was supported and funded by the UKRI NERC funded STORMY-WEATHER project. The study sets the stage for further investigation into the mechanisms driving compound wind-rain extremes and emphasizes the need for continued research to better understand the impacts of these events and to develop strategies for reducing risks associated with them. The use of high-resolution climate projections for the UK provided new insights into how the climate may change at a local scale and how changes in weather extremes may unfold in the coming years and decades.
