An extreme cold Central European winter such as 1963 is unlikely but still possible despite climate change

Abstract

Abstract. Central European winters have warmed markedly since the mid-20th century. Yet cold winters are still associated with severe societal impacts on energy systems, infrastructure and public health. It is therefore crucial to anticipate storylines of worst-case cold winter conditions, and to understand whether an extremely cold winter, such as the coldest winter in the historical record of Germany in 1963 (−6.3 °C or −3.4σ seasonal DJF temperature anomaly relative to 1981–2010), is still possible in a warming climate. Here, we first show based on multiple attribution methods that a winter of similar circulation conditions to 1963 would still lead to an extreme seasonal cold anomaly of about −4.9 to −4.7 °C (best estimates across methods) under present-day climate. This would rank as second-coldest winter in the last 75 years. Second, we conceive storylines of worst-case cold winter conditions based on two independent rare event sampling methods (climate model boosting and empirical importance sampling): winter as cold as 1963 is still physically possible in Central Europe today, albeit very unlikely. While cold winter hazards become less frequent and less intense in a warming climate overall, it remains crucial to anticipate the possibility of an extreme cold winter to avoid potential maladaptation and increased vulnerability.

Simulating record-shattering cold winters of the beginning of the 21st century in France

“…We use SWG simulations based on reanalysis data in order to assess the intensity of the worst-case winter scenario in France A study by Sippel et al (2023) has conducted a similar analysis of winter 1963 for Germany, using both ensemble boosting of the CESM2-ETH model and the SWG displayed in this paper. This paper provided an investigation of such winters focusing on France and a more in-depth analysis of the use of the analogues-SWG.…”