Invasives and climate change: Global synthesis of responses to extreme weather

Invasive species and climate change are two major threats to global biodiversity. With the ability to influence the impact of invasive species, climate change, however, manifests itself not just as increasing means, but also as more extreme weather events (EWEs), such as heatwaves, storms, floods and droughts.

In this meta-analysis of 443 studies, researchers systematically reviewed eight categories of responses of native and non-native species to five types of EWEs. In total, they synthesized more than 5,000 comparable measures of effects on 6, 7, and 10 classes of terrestrial, freshwater and marine organisms, respectively.

Overall, the authors found that non-native species experienced more positive effects from EWEs compared to native species. In terrestrial ecosystems, only heatwaves negatively affected non-native species, while cold spells and drought also had adverse impacts on natives. In freshwater ecosystems, native species responded negatively to nearly all types of EWEs, whereas while only storms showed negative effects on non-native species. Marine species, on the whole, were not significantly impacted by EWEs.

To explore areas of high overlap between EWEs and potential EWE-tolerant invaders, the authors used GBIF-mediated occurrences to model the distributions of non-native species from their meta-analysis, overlaying maps of EWE hotspots derived from various meteorological databases.

The combined risks of EWEs and invasions were widespread but varied significantly depending on the type of EWE. Heatwaves posed the greatest risks in Australia and the Americas, while storms were most threatening in the Caribbean and India. Flood risks were highest in South America and East Asia, whereas droughts posed the greatest combined risks in Europe and South America. Cold spell risks were most pronounced in high-latitude regions.