The influence of climate change on analogues of contrasting mid-latitude cyclones over the UK

Extreme extratropical storms present major socio-economic risks and are sensitive to anthropogenic climate change. Whilst robust projections of the aggregate properties of extreme storms have emerged from climate models in recent years, these average together storms with a range of contrasting dynamical structures and the influence of climate change on specific storm structures is much less well understood. Here, we adopt the storm track analogue approach to examine the influence of climate change on four contrasting historical storms 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 for both the present climate (1980–2010) and a high-emission future scenario (SSP3–7.0, 2070–2100).

Across each region of the UK, the overall number of storms decreases in future while the intensity of the most extreme storms increase, both in terms of precipitation and lower-tropospheric wind speed, aligning well with consensus storm projections. However, the analogues of specific storms exhibit contrasting future responses, indicating that storm-specific changes under anthropogenic warming can diverge from the aggregate signal. For example, whilst there is a reduction in the total number of storms in the region impacted by the Great Storm, there is a marked future increase in the number of storms with a trajectory similar to the Great Storm. Such changes are likely driven by regional variations in the conditions for baroclinic growth, or an increased influence of diabatic effects in future. Since individual storms are typically associated with distinct meteorological hazards, accounting for storm-specific responses is critical for assessing regional impacts and developing adaptation strategies.