PNNL

Abstract

Lakes are jeopardized by the impacts of climate change on ice seasonality and water temperatures. Yet, historical simulations have not been used to formally attribute observed changes in lake ice and temperature to anthropogenic drivers. Additionally, future projections of these properties are mostly limited to individual lakes or global simulations from single lake models. Here we uncover the human imprint on lakes worldwide using novel hindcasts and projections from five lake models. Reconstructed trends in lake temperature and ice cover in recent decades are extremely unlikely to be explained by pre-industrial climate variability alone and ice cover trends are consistent with lake model simulations under historical conditions, providing the first formal attribution of lake changes to anthropogenic climate change. Moreover, lake temperature, ice thickness, and ice cover scale robustly with air temperature across future climate scenarios. Importantly, the uncertainty in end-of-century impacts is dominated by the choice of emissions scenario rather than lake model or forcing types, showing that lake systems will greatly benefit from climate mitigation. Otherwise, these impacts would profoundly alter the functioning of worldwide lake ecosystems and the services they provide.