John Marshall
We explore the climate of an earth-like exoplanet by considering how the climate of earth might change if, for example, its obliquity were ranged from 0 to 90 degrees. High values of obliquity particularly challenge our understanding of climate dynamics because if obliquity exceeds 54 degrees, then polar latitudes receive more energy per unit area than do equatorial latitudes. Thus the pole will become warmer than the equator and we are led to consider a world in which the meridional temperature gradients, and associated prevailing zonal wind, have the opposite sign to the present earth, and the equatorial Hadley circulation exists where it is cold rather than where it is warm. And all this is going on in the context of a very pronounced seasonal cycle.

We present some of the descriptive climatology of solutions from a coupled atmosphere-ocean-ice model and describe how they shed light on the deeper questions of coupled climate dynamics that motivate them. We also review what they tell us about habitability on such planets.