StratoClim will produce more reliable projections of climate change and stratospheric ozone by a better understanding and improved representation of key processes in the Upper Troposphere and Stratosphere (UTS). This will be achieved by an integrated approach bridging observations from dedicated field activities, process modelling on all scales, and global modelling with a suite of chemistry climate models (CCMs) and Earth system models (ESMs). At present, complex interactions and feedbacks are inadequately represented in global models with respect to natural and anthropogenic emissions of greenhouse gases, aerosol precursors and other important trace gases, the atmospheric dynamics affecting transport into and through the UTS, and chemical and microphysical processes governing the chemistry and the radiative properties of the UTS. StratoClim will (a) improve the understanding of the microphysical, chemical and dynamical processes that determine the composition of the UTS, such as the formation, loss and redistribution of aerosol, ozone and water vapour, and how these processes will be affected by climate change; (b) implement these processes and fully include the interactive feedback from UTS ozone and aerosol on surface climate in CCMs and ESMs. Through StratoClim new measurements will be obtained in key regions: (1) in a tropical campaign with a high altitude research aircraft carrying an innovative and comprehensive payload, (2) by a new tropical station for unprecedented ground and sonde measurements, and (3) through newly developed satellite data products. The improved climate models will be used to make more robust and accurate predictions of surface climate and stratospheric ozone, both with a view to the protection of life on Earth. Socioeconomic implications will be assessed and policy relevant information will be communicated to policy makers and the public through a dedicated office for communication, stakeholder contact and international co-operation.