Three-dimensional persistence of temperature gradients on rapidly rotating runaway-greenhouse planets

Determine whether rapid planetary rotation and the associated small Rossby deformation radius preserve the strong equator-to-pole temperature gradients predicted by the one-dimensional diffusive Gen-EBM during the runaway greenhouse transition.

Background

Gen-EBM represents meridional heat transport through one-dimensional diffusion and therefore cannot explicitly resolve large-scale atmospheric circulation, latent-heat transport, or cloud-radiative feedbacks. In the fast-rotator experiments, this simplified treatment produces runaway-like attractors with global mean temperatures of approximately 600–750 K while polar regions remain below the freezing point of water.

The unresolved problem is whether such strong temperature contrasts would persist in a more physically complete three-dimensional climate system. The authors note that rapid rotation may limit atmospheric redistribution through a small Rossby deformation radius, but no three-dimensional general circulation model study has yet examined the runaway greenhouse transition for rapidly rotating planets.

References

Nevertheless, the extent to which rapid rotation and the associated small Rossby deformation radius would preserve such gradients remains an interesting open question.

— Gen-EBM: an energy balance model for terrestrial planets. Climate multistability from snowball to post-runaway greenhouse climates  (2610.12267 - Bhatnagar et al., 8 Oct 2026) in Section 4.5, “Model limitations” (subsection labeled “Model limitations”)