Data sets for article with the following abstract: Lakes and impoundments are important in the global carbon cycle, transporting, storing, processing and emitting significant amounts of carbon. Recent research shows that, from an atmospheric and climate change perspective, methane (CH4) is the most important carbon emission from lakes and impoundments, constituting >70% of the climate impact. Further, a recent analysis shows aquatic productivity (i.e., eutrophication) is the most important driver of CH4 emissions from lentic waters. Considering that aquatic productivity will greatly increase over the next century due to warming, increased runoff of production-limiting nutrients, and excess nutrients from augmented agricultural production and human sewage release, a concomitant increase in aquatic CH4 emissions may occur. Here we analyze the future impacts of enhanced productivity on CH4 emissions and show that, conservatively, inland water's productivity will increase by 50-300%, which in turn will drive up CH4 emissions by 30-100 Tg of CH4-C y-1 (30-90%). This increased emission has a potential atmospheric CO2 impact of 1.8-2.6 Pg C-CO2eq yr-1, which is equivalent to19-33% of the current effect of annual CO2 emissions from burning fossil fuels. The net change in CH4 emission over current conditions will have an effect equal to current estimates of CO2 emissions resulting from land use change (e.g., conversion of forest into agricultural land) or 14-53% of oceanic carbon sequestration. Thus, it is not only important to limit eutrophication to preserve fragile water supplies, but also to avoid acceleration of climate change.