Past and Projected Weather Pattern Persistence with Associated Multi-Hazards in the British Isles

Abstract

Hazards such as heatwaves, droughts and floods are often associated with persistent weather patterns. Atmosphere-Ocean General Circulation Models (AOGCMs) are important tools for evaluating projected changes in extreme weather. Here, we demonstrate that 2-day weather pattern persistence, derived from the Lamb Weather Types (LWTs) objective scheme, is a useful concept for both investigating climate risks from multi-hazard events as well as for assessing AOGCM realism. This study evaluates the ability of a Coupled Model Intercomparison Project Phase 5 (CMIP5) multi-model sub-ensemble of 10 AOGCMs at reproducing seasonal LWTs persistence and frequencies over the British Isles (BI). Changes in persistence are investigated under two Representative Concentration Pathways (RCP8.5 and RCP4.5) up to 2100. The ensemble broadly replicates historical LWTs persistence observed in reanalyses (1971–2000). Future persistence and frequency of summer anticyclonic LWT are found to increase, implying heightened risk of drought and heatwaves. On the other hand, the cyclonic LWT decreases in autumn suggesting reduced likelihood of flooding and severe gales. During winter, AOGCMs point to increased risk of concurrent fluvial flooding-wind hazards by 2100, however, they also tend to over-estimate such risks when compared to reanalyses. In summer, the strength of the nocturnal Urban Heat Island (UHI) of London could intensify, enhancing the likelihood of combined heatwave-poor air quality events. Further research is needed to explore other multi-hazards in relation to changing weather pattern persistence and how best to communicate such threats to vulnerable communities.

Weather persistence on sub-seasonal to seasonal timescales: a methodological review

“…The residence time approach can characterise episodic, state, and also global stationarity, and is particularly useful for predictability and risk assessment (De Luca et al, 2019;Francis et al, 2020;Berkovic and Raveh-Rubin, 2022). From the time perspective, large values of 𝑅(𝑡) indicate the most stationary periods.…”

Knowledge gaps in our perceptual model of Great Britain's hydrology

“…Probabilistic event attribution studies have shown that historical greenhouse gas emissions have already contributed to increased risk of flooding within the context of specific extreme events (quantified for the floods in winter 2013–14, which affected large parts of GB, by Schaller et al, 2016 and Kay et al, 2018). Future GB precipitation and temperature extremes are expected to change in both magnitude and frequency, and even in the type of event (De Luca et al, 2019; Kendon et al, 2014). An increasing frequency of localized summer storms is projected to go hand in hand with more frequent and more widespread droughts (Guillod et al, 2018).…”

Special Issue: 10th Anniversary of Atmosphere: Climatology and Meteorology

“…The second topic area included seven articles [9][10][11][12][13][14][15] and covered a diverse number of phenomena related to extremes and teleconnections that generally operated on subseasonal and seasonal time scales. The sediment discharge in the Amazon Basin [9] was examined and modelled using in situ and satellite derived information in the river sediment discharge for Amazonia (RSDA) model.…”

“…The association of natural hazards with persistent weather types occurring over the British Isles in the late 20th century was studied in [12], and this information was then used to determine whether or not these natural hazards would become more common by 2100. This work successfully showed that weather types or analogues are a useful way to project what kind of changes in hazardous weather may occur at the end of the 21st century in different climate change scenarios.…”

“…A few of these teleconnection patterns were associated with a linear influence (positive teleconnection sign-negative STA, and vice versa). While [12] examined future climate scenarios, [13] demonstrated that some of these teleconnection-STA associations showed promise for use in sub-seasonal forecasting (one-to-three-week time frame) for southern China.…”