Recovering the Earth's Climate with the ROCKE3D Global Climate Model

The burgeoning field of climate modeling of hypothetical terrestrial exoplanets has largely, to date, focused on the important roles of orbital dynamics and atmospheric gas mixtures in producing climate states. Yet, Earth's habitable modern climate state, while coarsely driven by orbit and atmospheric pressure and gas mixtures, is finely tuned by features such as surface albedo variations driven by snow and ice cover, topography and continental distribution coupled with ocean heat transport, and biological systems.

Using the ROCKE3D global climate model with a fully coupled dynamic ocean, we conducted a series of simulations with modern Earth orbital parameters and atmospheric gas mixtures that iteratively added aspects of modern Earth's surface (e.g., continents, continental distribution, topography, soil properties, and vegetation) to recover a true representation of modern terrestrial climate. These simulations coarsely mimic the formation of continents, topographic variation, soil evolution, and the development and expansion of surface vegetation that occurred during Earth's history. We find these factors warm the modern terrestrial climate by 10-15 K, from near freezing to the values seen today. These results are relevant to understanding uncertainties driven by unobservable surface features in future climate characterization of terrestrial exoplanets.