Gen-EBM: an energy balance model for terrestrial planets. Climate multistability from snowball to post-runaway greenhouse climates
Abstract
Climate multistability and tipping points are fundamental properties of planetary climates that depend sensitively on climate feedbacks. We introduce the Geneva Energy Balance Model (Gen-EBM), a new 1-D latitudinal EBM for rapid exploration of terrestrial planet climates, and use it to investigate how planetary rotation, eccentricity, and thermal inertia shape climate attractors and multistability. Gen-EBM is implemented in Rust and builds on previous exoplanet EBMs by incorporating a temperature-dependent outgoing longwave radiation prescription spanning Earth-like, runaway-onset, and post-runaway greenhouse regimes. We construct bifurcation diagrams from ensembles of simulations and explore the effects of rotation rate, orbital eccentricity under the mean-flux approximation, and surface thermal inertia. Including post-runaway greenhouse states substantially enlarges the parameter space over which multiple climate states coexist. Within our model framework, slow rotators approach the spatially homogeneous limit and maintain broader temperate stability ranges, whereas fast rotators develop strong equator-to-pole temperature gradients that narrow the temperate branch. Under the mean-flux approximation, increasing eccentricity enhances climate variability and can alter the attractor structure itself. The critical eccentricity at which temperate climates disappear depends strongly on thermal inertia, with ocean-rich planets remaining stable to larger eccentricities than land-dominated planets. Gen-EBM therefore broadens rapid parameter-space exploration to climates spanning temperate, runaway-onset, and post-runaway regimes. Its computational efficiency and flexibility make it a valuable bridge between simple climate models and 3-D general circulation models.
Related
- Stochastic Snowball States in Planetary Climate
- The diversity of planetary climates in the Solar System as a basis for reflection and work on the study of exoplanet climates
- High-CO2 Climates and Observables in the Outer Habitable Zone
- Editorial: Dynamic exospheres of terrestrial bodies through the solar system
- Magnitude of stable iron isotope fractionation limited by multiple stages of terrestrial core formation
BibTeX
@misc{bhatnagar2026genebm,
title = {{Gen-EBM: an energy balance model for terrestrial planets. Climate multistability from snowball to post-runaway greenhouse climates}},
author = {Siddharth Bhatnagar and Emeline Bolmont and Maura Brunetti and Jérôme Kasparian and Tim Kallioinen and Marine Leyvraz and Guillaume Chaverot and Yonatan Birhanu Haile and Dóra Takács},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.12267},
eprint = {2610.12267},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.12267},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Gen-EBM: an energy balance model for terrestrial planets. Climate multistability from snowball to post-runaway greenhouse climates
AU - Siddharth Bhatnagar
AU - Emeline Bolmont
AU - Maura Brunetti
AU - Jérôme Kasparian
AU - Tim Kallioinen
AU - Marine Leyvraz
AU - Guillaume Chaverot
AU - Yonatan Birhanu Haile
AU - Dóra Takács
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.12267
UR - https://arxiv.org/abs/2610.12267
AB - Climate multistability and tipping points are fundamental properties of planetary climates that depend sensitively on climate feedbacks. We introduce the Geneva Energy Balance Model (Gen-EBM), a new 1-D latitudinal EBM for rapid exploration of terrestrial planet climates, and use it to investigate how planetary rotation, eccentricity, and thermal inertia shape climate attractors and multistability. Gen-EBM is implemented in Rust and builds on previous exoplanet EBMs by incorporating a temperature-dependent outgoing longwave radiation prescription spanning Earth-like, runaway-onset, and post-runaway greenhouse regimes. We construct bifurcation diagrams from ensembles of simulations and explore the effects of rotation rate, orbital eccentricity under the mean-flux approximation, and surface thermal inertia. Including post-runaway greenhouse states substantially enlarges the parameter space over which multiple climate states coexist. Within our model framework, slow rotators approach the spatially homogeneous limit and maintain broader temperate stability ranges, whereas fast rotators develop strong equator-to-pole temperature gradients that narrow the temperate branch. Under the mean-flux approximation, increasing eccentricity enhances climate variability and can alter the attractor structure itself. The critical eccentricity at which temperate climates disappear depends strongly on thermal inertia, with ocean-rich planets remaining stable to larger eccentricities than land-dominated planets. Gen-EBM therefore broadens rapid parameter-space exploration to climates spanning temperate, runaway-onset, and post-runaway regimes. Its computational efficiency and flexibility make it a valuable bridge between simple climate models and 3-D general circulation models.
ER -