Butterfly abundance changes in England are well associated with extreme climate events

Climate change exerts significant impacts on ecosystems through extreme climate events (ECEs), which are linked to various climate variables and can occur in different seasons. However, previous studies predominantly focus on a single type of ECE within specific seasons. We address this research gap by examining four typical types of ECEs: droughts, pluvials, heatwaves, and coldwaves, which are consistently defined and identified on a daily scale using a recently proposed statistical method. Butterflies in England serve as our study subject since their life stages occur throughout the year, and we had access to a 45-year dataset encompassing 57 butterfly species. First, we analyzed the correlation between abundance changes and the severity of ECEs, revealing varying sensitivity to ECEs across different life stages. Notably, abundance changes are negatively correlated with the severity of heatwaves in the hibernation, egg, and larval stages, as well as with the severity of pluvials in the larval, pupal, and adult stages. Second, we identified the most extreme climate events (MECEs) in England in the period from 1950 to 2020 and linked them with synchronized abundance changes for all species. MECEs in the sensitive stages of butterflies are frequently (for eight out of 11 MECEs) associated with synchronized decreases in their abundance. Our findings underscore the importance of considering diverse types of ECEs across all seasons to gain insights into their potential ecosystem effects. We draw attention to the fact that our analyses are primarily data-driven, with limited ecophysiological interpretation.