Reconstructing and simulating the warming patterns of the Cenezoic: reviewing advances and challenges

As we place stock in the projections made by state-of-the-art coupled climate models, their ability to simulate past climate change represents an important test. Climate modeling efforts targeting past warm climates have focused in particular on intervals within the Pliocene, Miocene and Eocene Epochs. A salient feature seen across simulations of all three Epochs is a general underestimation of high latitude to subtropical warming and an overestimation of tropical warming. The severity of this model-data discord within each interval continues to evolved as new and revised temperature reconstructions become available and climate models progress in sophistication (specifically in terms of cloud microphysics and aerosol indirect effects). The nature of cloud radiative responses emerges as a key factor determining warming patterns. Challenges remain in constraining CO₂ and aerosol forcing, as well as the reconstructed warming patterns within these past warm climates. That said, taking a multi-warm-climate approach can help in establishing the extent to which cloud feedback mechanisms can consistently explain the patterns of warming, and the hydrological cycle response across these past warm climates.