How will climate change impact North Atlantic storms?

North Atlantic storms present one of the major weather risks for West (NW) Europe. Their associated strong winds and heavy precipitation can result in wind damage both coastal inland flooding. Notable recent examples include St Jude's Day storm October 2013 which brought hurricane-force to NW Europe, including record-strong Denmark loss 17 lives. In November December that year, intense rainfall with a series led widespread UK flooding was particularly severe over Somerset Levels, timing Xaver on 5 generated surge around Irish Seas. Understanding predicting how might respond climate change is therefore essential assessing future informing adaptation strategies. This briefing focuses track traverses Ocean extends strongest impacts usually occurring autumn winter. Over most Northern Hemisphere, models project midlatitude tracks will, average, shift further poleward under change. Coupled general decrease number storms. If this pattern occurred Atlantic, expect reduction impacting indeed case summer, but wintertime does not follow simple picture; instead, it projected extend more strongly eastward Europe resulting an enhanced risk region. Comprehensive analyses across wide range global suggest increase occurrence 2–4% by end century (Zappa et al., 2013). The quoted represents scenario uncertainty two different greenhouse gas emissions pathways, corresponding warming levels approximately 2–4 degC respectively. There are additional uncertainties accounted for, due internal variability system. A full analysis generation (CMIP6) has yet be completed, initial studies indicate broadly similar changes per degree (Harvey 2020). On level individual storms, substantial robust increases expected. same suite model simulations above 9–18% average from Although expected weaken, again do picture modest 0.4–0.9% near-surface speeds century. Increases severity also expected, predominantly rising sea (Murphy 2018). large-scale contrast temperature exists between tropics Arctic. Climate warm Arctic than through process known as polar amplification, acting generally reduce storminess midlatitudes. However, intensification bucks trend reasons fully understood. It may partly arise region slower ocean central circulation, local north–south gradient surface stronger potential growth there (Gervais 2019). Alternatively, hemispheric-scale dynamical playing role (Ciasto 2016). consistent increased availability moisture air temperatures. One key research question currently being addressed extent current accurately represent For example, small-scale atmospheric processes resolved these models, sting jets embedded convective precipitation, have locally amplify manner captured projections.