The warming climate is driving an increase in urban rat populations and increasing the strain on infrastructure and pest control, researchers say.
A team from the University of Richmond in the US analysed public complaint and inspection data from 16 cities around the world and found strong links between rising numbers of rats and human population density, urbanisation of cities and warming temperatures.
Of the cities assessed, 11 had “significant increasing trends” in rat numbers, including Washington DC, New York and Amsterdam. Only three cities assessed during the study experienced decline: Louisville, Tokyo and New Orleans.
In particular, cities experiencing greater temperature increases over time saw larger increases in rat numbers, while those with denser human populations and more urbanisation also saw the numbers increase.
“The most concerning of these connections we found is the link between climate warming and rat trends, as global temperatures are beyond the control of individual...