Responses of global waterbird populations to climate change vary with latitude

Gaps in geographic coverage of species abundance data, especially in the tropics, make determining species' responses to climate change difficult. Modelling a dataset on global waterbird abundance shows abundance declines in the tropics and increases at higher latitudes when temperatures increase. Most research on climate change impacts on global biodiversity lacks the resolution to detect changes in species abundance and is limited to temperate ecosystems. This limits our understanding of global responses in species abundance-a determinant of extinction risk and ecosystem function and services-to climate change, including in the highly biodiverse tropics. We address this knowledge gap by quantifying the abundance response of waterbirds, an indicator taxon of wetland biodiversity, to climate change at 6,822 sites between 55 degrees S and 64 degrees N. Using 1,303,651 count records of 390 species, we show that with temperature increase, the abundance of species and populations decreased at lower latitudes, particularly in the tropics, but increased at higher latitudes. These contrasting latitudinal responses indicate potential global-scale poleward shifts of species abundance under climate change. The negative responses to temperature increase in tropical species are of conservation concern, as they are often also threatened by other anthropogenic factors.