Future climate scenarios predict increased climatic variability such as more intense heat waves, longer dry spells, and bigger storms. Ecological research on climate change impacts typically focuses on means and often neglects the consequences of more frequent extreme events. Particularly in regions where climatic conditions are often limiting factors, such as water availability in arid and semiarid ecosystems, increased variability in weather events may result in novel spatial and temporal dynamics of water balance to which ecosystem productivity, species composition, and carbon storage may respond in nonlinear ways. Consequently, understanding trajectories and thresholds of ecosystem responses to climatic variability will be important for effective land management. For instance, an increase in the frequency of more intense and earlier summer dry periods in the intermountain region may shift the seasonal water balance from storage-dominated to pulse-dominated – a change that would likely shift vegetation dominance from woody species to grasses. This session will include speakers from grassland, shrubland, and semi-arid forested systems, as well as speakers that focus on ecotone dynamics between these systems. Speakers will address the consequences of climate variability for a wide range of ecosystem processes for which temporal historical records and/or future predictions are available. Talks will be organized in groups starting with ecosystem water balance as an intermediary between climate variability and ecosystem functioning, followed with talks addressing vegetation composition, and third with talks examining impacts on ecosystem productivity and carbon balance consequences. Comparing and contrasting results across biomes and across different aspects of climate variability may lead to further synthesis products. This session aims to review ongoing research and to provide a roadmap for future research to improve our understanding of how to manage arid and semiarid ecosystems under increased frequency of extreme events.