The earth's climate is highly variable on all spatial and temporal scales. These changes in variability (spatial or temporal) can impact the recurrence frequency of extreme events which can have catastrophic effects on society. Yet, it is unclear if a warmer future is one with more or less climate variability, and at which scales, as a multitude of feedbacks are involved, and the instrumental record is short.
The seasonal cycle, for instance, is the largest perturbation in the system. We need to better constrain its nonlinear interactions with other climate phenomena from large-scale internal modes of variability on an interannual timescale, to orbital parameters on a glacial time scale, to allow better projections of future climate variability.

We welcome contributions that improve quantification, understanding and prediction of past, present and future climate variability in the Earth System. Discussion is invited across spatial and temporal scales, from local to global and synoptic to orbital. The session is multidisciplinary and brings together studies related to atmospheric science, oceanography, glaciology and paleoclimatology to examine the complementarity of ideas and approaches.

This session aims to provide a forum to present work on

* State dependency: The relationship between changes in the mean state (e.g. glacial to interglacial, preindustrial to present to future), and higher-order moments of relevant climate variables, to changes in extreme event occurrence and the predictability of climate.

* Timescale dependency: The linkage between synoptic-scale, seasonal scale and slower (interannual to millennial) climate variability and extreme event recurrence.

* Feedbacks and Mechanisms: The role of ocean, atmosphere, cryosphere and land surface processes in fostering long-term climate variability through linear – or nonlinear – feedbacks and mechanisms. The interaction of external forcing (e.g. orbital forcing) and internal variability, such as mechanisms for synchronization and pacing of glacial cycles and the impact on seasonality

* Seasonality: What are the varying responses of land, ocean, and atmosphere to seasonality, and how do the biological and physical components differ? How can we use the seasonal cycle observed in proxy records as a tool to better understand future responses to climate change? What are the limitations?


The session is also an opportunity to present and discuss first results of the Past Global Changes (PAGES) working group on Climate Variability Across Scales (CVAS), and is convened in conjunction with participants from the 2017 Advanced Climate Dynamics Course (ACDC) on The Dynamics of the Seasonal Cycle.