The era of atmospheric characterization of terrestrial exoplanets is just around the corner. Prior modeling of observables is crucial so that one can prepare for challenges in data interpretation.
Planets are inherently complex objects with multiple interacting systems, including 3-D atmospheric circulation patterns, atmospheric chemistry, and ice formation that affect the climate. As a result, we need a variety of models that use different approaches to simulating these planetary atmospheres. However, many of these models are themselves very complex, and their outputs can vary from one another for a variety of reasons. To address these issues, GCM intercomparisons have been widely used by the Earth science community. For instance, the Coupled Model Intercomparison Project (CMIP) initiated in 1995, currently in its version 6 (Eyring et al., 2016), focuses on the differences in GCM responses to forcings from anthropogenic climate change. CMIP is crucial to assess model performances, to quantify the difference between the model predictions and to understand the model responses. To our knowledge only two inter-model comparisons have been applied to exoplanets, Yang et al., (2016, 2019) and the TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI, Fauchez et al. 2020). In this talk we will discuss the lessons learned from these two projects, the important role that inter-model comparisons can have for exoplanet studies and bridging for future larger projects such as the Climates Using Interactive Suites of Intercomparisons Nested for Exoplanet Studies (CUISINES) NExSS Working Group.