# Hungary's Current Climate Conditions Converge With the North‐Mediterranean of the 1980s: A Case Study in Mediterranean Ant Species New to Hungary

## TL;DR

Climate change is making Hungary's climate similar to 1980s Mediterranean regions, increasing the risk of invasive ant species from the Mediterranean.

## Contribution

This study links climate convergence to the potential invasion of Mediterranean ant species in Hungary.

## Key findings

- Hungary's current climate has become similar to the 1980s Mediterranean climate, reducing climatic barriers for invasive ants.
- Four non-native Mediterranean ant species have been recorded in Hungary, indicating ongoing invasions.
- Climate change has made Hungarian habitats potentially suitable for Mediterranean ants within 40 years.

## Abstract

Climate change reshapes our environment, affects species distributions, and threatens biodiversity. Our warming climate allows species to broaden their ranges naturally by expanding or shifting their distribution areas towards available, previously unsuitable areas, or anthropogenically by establishing breeding populations followed by active dispersion after intentional or unintentional human introduction. This effect, coupled with the ongoing intensification of human transport of goods, accelerates the rate of biological invasions considerably. Ants have a remarkable ability to disperse and become invasive, resulting in profound ecological and economic damage. Most relevant studies in the Carpathian Basin (Central Europe) focus solely on identifying new non‐native species, typically without exploring the relationship between climate change and species invasions. Here, we studied how climate change might aid Mediterranean ants' invasion of the Carpathian Basin. First, we monitored non‐native Mediterranean ant species in Hungary (occupying most of the Carpathian Basin) and recorded four of such species. Then, we compared the historical Mediterranean climate (1980s) with the current Hungarian climate of the four species' habitats to assess whether Hungarian conditions have converged with those Mediterranean conditions from which these species originate. We found that the climate of both areas changed significantly during the last 40 years by becoming hotter and drier. This change resulted in the disappearance of the climatic differences that previously existed between the 1980s Mediterranean region and 1980s Hungary (higher radiation and minimum temperatures in the former). When comparing 1980s Mediterranean climate to current Hungarian climate, these differences have largely vanished. Our results demonstrated that climate change could make Hungarian habitats climatically suitable for Mediterranean species in 40 years, implying significant risks of invasions currently and in the near future.

Climate change reshapes our environment, affects species distributions, and threatens biodiversity. We show that historical climate of certain Mediterranean ant species' native areas are similar to the contemporary climate of the same ant species' non‐native Hungarian areas/occurrences. Our results demonstrate that climate change could make Hungarian habitats climatically suitable for Mediterranean species in 40 years, implying significant risks of invasions currently and in the near future.