The study by 153 researchers from 40 countries found that climate factors such as temperature and humidity strongly influence the carbon cycles of river ecosystems. In northern latitudes, temperature plays a major role, while nutrient loads are particularly important closer to the equator. The carbon cycle is crucial for the functioning of systems on all scales, from local food webs to the global climate. “River ecosystems play significant roles in the global carbon cycle by regulating rates of decomposition and transporting organic matter to the oceans, but we have only a rudimentary understanding of how decomposition rates vary from river to river,” says former Eawag PhD student Scott Tiegs, now biology professor at Oakland University in Michigan, who led the study.