Climate change effects on analogues of contrasting extratropical cyclones over the UK

Abstract. Extreme extratropical cyclones present major socio-economic risks in the United Kingdom and are sensitive to anthropogenic climate change. Robust projections of the aggregate properties of extreme cyclones based on climate-model output have emerged in recent years. However, such projections average together cyclones with a range of contrasting dynamical characteristics potentially obscuring climate change effects on particular types of cyclones and the airstream structures within them. Here, we adopt the cyclone track analogue approach to examine the influence of climate change on four contrasting historical cyclones impacting the UK: Martin in December 1999, the Great Storm in October 1987, Arwen in November 2021, and Ophelia in October 2017. Analogues are identified in the recently-produced CANARI large ensemble simulations for both the present climate (1980–2010) and a high-emission future scenario (SSP3–7.0, 2070–2100).

The overall number of cyclones decreases in future while the intensity of the most extreme cyclones increase, in both precipitation rate and lower-tropospheric wind speed, aligning well with consensus cyclone projections. However, track analogues exhibit contrasting responses, indicating that cyclone-specific changes under anthropogenic warming can diverge from the aggregate signal. For example, there is a marked future increase in the number of cyclones with a path similar to the Great Storm. Such changes are likely driven by regional variations in the conditions for baroclinic growth. Since individual cyclones are typically associated with distinct meteorological hazards, accounting for cyclone-specific responses is critical for assessing regional impacts and developing adaptation strategies.