The composition and temperature structure of Earth’s atmosphere varies through time in response to a variety of natural and anthropogenic drivers. This session aims to address the current scientific challenges that surround measuring, modelling and attributing the drivers of long-term trends of temperature and ozone profiles whose changes are closely related in the middle atmosphere. The session is inspired by two ongoing SPARC activities on ozone trends (LOTUS, Long-term Ozone Trends and Uncertainties in the Stratosphere) and temperature changes (ATC, Atmospheric Temperature Changes and their Drivers). We welcome the latest studies that use observational datasets (e.g. from satellite, in-situ and ground-based instruments) and numerical models to investigate global and regional changes in middle atmospheric ozone and temperature in the past, present and future. The discussion of recent techniques to improve, intercompare and regress data records –especially merged data sets– will be central to assessing long-term trends, their significance and spatial pattern. We particularly encourage studies that employ novel observational datasets and advanced chemistry-transport models to attribute temperature and ozone changes to natural and anthropogenic drivers, hereby aiming to further the connections between the atmospheric observation and climate modelling communities.