The Madden-Julian Oscillation (MJO) is the dominant source of subseasonal atmospheric variability in the tropics and significantly influences the predictability of global weather and climate. Changes in its activity and predictability due to human-induced global climate change have profound implications for future global weather predictions. Here, we examine changes in MJO predictability in reanalysis and climate model data and find that MJO predictability has increased over the past century. This increase can be attributed to anthropogenic warming and is projected to continue into the 21st century. The increased predictability is accompanied by stronger MJO amplitude, more regular oscillation patterns, and organized eastward propagation under global warming. Our results suggest that greenhouse warming will enhance MJO predictability with far-reaching implications for global weather prediction. (Danni Du, Aneesh C. Subramanian, Elizabeth Bradley)