The mosquito-borne viral disease Chikungunya is usually found in tropical areas. Researchers have now discovered how climate change is facilitating the spread of the Chikungunya virus. Even if climate change only progresses moderately – as scientists are currently observing – the risk of infection will continue to increase in many regions of the world through the end of the 21st century. If climate change continues unchecked, the virus could even spread to southern Europe and the United States.