Is lake ice disappearing from the Earth system? Luke Grant2, Zeli Tan7, Marjorie Perroud8, Victor Stepanenko9, Bram Droppers3, Annette B.G. Janssen3, R. Iestyn Woolway4, Martin Schmid11, Jacob Schewe6, Fang Zhao6, Gosia Golub5, Rafael Macré10, Don Pierson5, Wim Thiery1,2, Inne Vanderkelen2, Sonia Seneviratne1 1 ETH Zurich, Institute for Atmospheric and Climate Science, 8092 Zurich, Switzerland.2 Vrije Universiteit Brussel, Department of Hydrology and Hydraulic Engineering, Brussels, Belgium.3 Wageningen University & Research, Water systems and Global Change, Wageningen, the Netherlands.4 Dundalk Institute of Technology, Dundalk, Ireland5 Uppsala University, Dept of Ecology and Genetics / Limnology, Uppsala, Sweden.6 Potsdam Institute for Climate Impact Research, 14473 Potsdam, Germany7 Pacific Northwest National Laboratory, Richland, WA, USA8 University of Geneva, Institute for Environmental Sciences, Carouge, Switzerland9 Lomonosov Moscow State University, Moscow, Russia10 Catalan Institute for Water Research, Girona, Spain11 Eawag: Swiss Federal Institute of Aquatic Science and Technology, Surface Waters - Research and Management - Kastanienbaum, Switzerland Proposed session: HS10.9 - Lakes and Inland Seas in a Changing EnvironmentCorresponding author’s e-mail address: luke.grant@vub.be Lakes offer manifold ecosystem services and their ice cover stabilizes lake physics, biogeochemistry and ecological processes. The impacts of climate change on lake ice and lake temperatures are well documented for individual lakes and regions through site specific studies. Yet, future global projections of these variables are mostly limited to empirical approaches and singular, coarse-resolution lake model simulations forced by individual climate model outputs. Through the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) we offer an improved global analysis of the lake temperature (2m depth), lake ice cover duration and lake ice thickness projections of six uncalibrated, global-scale lake models to assess the fate of future lake ice and lake temperatures. Lake model simulations were performed on a generic lake within each lake-containing land cell of a global 0.5o grid. Simulations were at daily resolution and forced by four bias-corrected global climate models from the Coupled Model Intercomparison Project version 5 (CMIP5) for pre-industrial to future periods (1661-2099) and representative concentration pathways 2.6, 6.0 and 8.5. In all scenarios, a nearly unanimous increase in lake temperatures and disappearance of lake ice is projected. The largest reductions in ice thickness and duration will occur in northern latitudes and coastal regions, respectively. Simulations show a greater shift in the timing of ice break-up rather than the onset of ice cover. These geographical and seasonal trends require further statistical analysis to clarify their significance. In general, discrepancies in the projected magnitudes of change for lake ice and temperature under different RCPs underline the benefit of mitigating climate change as preventative to large changes in the biogeochemistry and ecology of lakes.