MITgcm sheds light on climate–vegetation–fire feedbacks in the early Triassic.

Reporting by Helen Hill for MITgcm

A new study published in Communications Earth & Environment revisits one of Earth’s most turbulent chapters – the Early Triassic, roughly 250 million years ago – through the lens of wildfire dynamics. Led by Franziska Blattmann and collaborators, the research combines geochemical evidence from Arctic sediments with advanced climate modeling to unravel how fire, vegetation, and climate interacted during a time of global upheaval.

The findings challenge long-standing assumptions about a “charcoal gap” in the Early Triassic, suggesting that wildfires were far from absent. Instead, they were shaped by complex feedbacks between shifting vegetation and climate states—insights made possible by the MIT General Circulation Model (MITgcm).

The Early Triassic followed the Permian-Triassic mass extinction, Earth’s most severe biodiversity crisis. This interval saw extreme greenhouse conditions, oscillating climates, and major shifts in terrestrial ecosystems. Yet, evidence for wildfire activity – typically preserved as charcoal – has been scarce, leading to the hypothesis of a global collapse in fire systems.

Blattmann’s team took a different approach: analyzing polycyclic aromatic hydrocarbons (PAHs), molecular fingerprints of combustion, in sediment cores from Spitsbergen. Their results revealed distinct pulses of PAHs across the Smithian–Spathian boundary, pointing to increased wildfire activity coinciding with vegetation turnover from lycophytes to gymnosperms.

To move beyond local observations, the researchers turned to MITgcm. Coupled with the BIOME4 vegetation model, MITgcm allowed the team to simulate alternative climate “steady states” for Permian-Triassic paleogeography: hot-house, warm-house, and cold-house scenarios.

These simulations revealed striking contrasts. Transitions from hot to cold states involved surface air temperature shifts of about 10 °C and significant changes in precipitation patterns. In the cold state – still warmer than today – conditions became drier overall but featured more seasonal precipitation. When paired with BIOME4, these climate states predicted biome shifts from dry shrublands to temperate forests near the study site, increasing biomass by roughly 30%.

Such changes in vegetation and hydrology would have profoundly influenced fire regimes. “Our modeling shows that cooler, drier climates could paradoxically lead to more burned biomass over long timescales,” says lead author Franziska R. Blattmann. This counterintuitive result underscores the importance of dynamic vegetation feedbacks, which static fire models often overlook.

The integration of MITgcm outputs with geochemical proxies provided a mechanistic explanation for the observed PAH pulses. As gymnosperms replaced lycophytes, fuel composition shifted toward more resinous, woody material – altering fire intensity and residue chemistry. Meanwhile, climate transitions amplified these effects by reshaping biome distribution and seasonal moisture availability.

By bridging sedimentary evidence with global climate simulations, the study demonstrates how Earth system models can illuminate processes that leave only fragmentary traces in the rock record. “Without MITgcm, we would lack the spatial and temporal context to interpret these wildfire signals,” Blattmann notes.

Beyond its paleontological significance, the research offers lessons for modern Earth system science. Fire–climate–vegetation feedbacks remain a major uncertainty in projecting future wildfire risk under anthropogenic warming. The Early Triassic, with its high CO₂ levels and extreme climates, serves as a natural experiment for understanding these interactions.

Story image: Wildfire (Wikimedia)

About the Researchers

Dr Franziska Blattmann is a member of the Geoscience Department at Aarhus University. The research was part of her PhD conducted the Faculty of Geoscience and Environment at the University of Lausanne in Switzerland.

All MITgcm computations were conducted by the team at the University of Geneva, including in particular Charline Ragon, who has worked extensively with MITgcm during her PhD and has more publications on this topic (see Related Publications below). Charline’s PhD supervisor is Maura Brunetti (Jurassic Currents)

This Month’s Featured Publication

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Akinjole, S. O. and Capps, S. L. (2025), GEOS-Chem-hyd: enabling source-oriented sensitivity analysis with GEOS-Chem, EGUsphere [preprint], doi: 10.5194/egusphere-2025-4543

Arora, Rahul and Liton Majumdar (2025), Quantifying the differences in transmission and emission spectra of hot
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Bertin, C., et al (2025), Colored dissolved organic matter (CDOM) alters the seasonal physics and biogeochemistry of the Arctic Mackenzie River plume, Biogeosciences, doi: 10.5194/bg-22-6607-2025

Bodner, A., Balwada, D., & Zanna, L. (2025), A data‐driven approach for parameterizing ocean submesoscale buoyancy fluxes, Journal of Advances in Modeling Earth Systems, doi: 10.1029/2025MS004991

Bolioudakis, Tilemachos et al (2025), Eulerian and Lagrangian characterization of a high amplitude convectively unstable shoaling internal solitary wave in two dimensions, via ResearchSquare, doi: 10.21203/rs.3.rs-7906656/v1

Cai, Jingyao et al (2025), Intensifying intraseasonal oscillation of South China Sea winter upper-layer circulation in a warming climate, Environ. Res. Commun., doi: 10.1088/2515-7620/ae1a30

Campos-Gonzales, Fernando E. et al (2025), Amplification of the Divergent Component From Balanced Motions and Forward Kinetic Energy Cascade in an Ocean-Atmosphere Simulation, JGR Oceans, doi: 10.1029/2025JC022479

Carone, L. et al (2025), Exoplanet climate characterization with transit asymmetries a comprehensive population study from the optical to the infrared, arXiv: 2511.01548

Chen, Tao and Hao Ding (2025), Comparative analysis of the impact of different environmental loading products on contemporary vertical land motion of mainland China from multigeodetic measurements, Geophysical Journal International, doi: 10.1093/gji/ggaf407

Jarugula, S., Lee, T., Wang, O., & Fournier, S. (2025), Maritime continent water cycle as a key forcing for decadal variation of upper‐ocean salinity in the southeast Indian Ocean, Journal of Geophysical Research: Oceans, doi: 10.1029/2025JC022733

Ma, Yuchen et al (2025), Standing wave-induced tidal shear in a submarine canyon in the Rockall Trough, via EartharXiv, doi: 10.31223/X57T98

Melin, E. et al (2025), Exploring Scientific Debt: Harnessing AI for SATD Identification in Scientific Software, arXiv: 2511.17368

Moses, William S. et al (2025), DJ4Earth: Differentiable, and Performance-portable Earth System Modeling via Program Transformations, ESS Open Archive, doi: 10.22541/essoar.176314951.18114616/v1

Poinelli, M. et al (2025), Small‐scale, high‐frequency ice, and ocean processes in the Amundsen Sea Embayment, West Antarctica, Journal of Advances in Modeling Earth Systems, doi: 10.1029/2025MS005098

Poinelli, M., Siegelman, L. & Nakayama, Y. (2025), Ocean submesoscales as drivers of submarine melting within Antarctic ice cavities, Nat. Geosci., doi: 10.1038/s41561-025-01831-z

Shen, Z., Yang, Y., Hu, J., & Zhang, S. (2025), Impact of topography on submesoscale ageostrophic kinetic energy in the Kuroshio south of Japan, Journal of Geophysical Research: Oceans, doi: 10.1029/2025JC022880

Song, R. et al (2025), Deep Arctic Ocean warming enhanced by heat transferred from deep Atlantic, Science Advances, doi: 10.1126/sciadv.adx9452

Sterl, Miriam F. et al (2025), Estimating cross-stream isopycnal eddy diffusivity from mooring observations in the Southern Ocean, via ESS Open Archive, doi: 10.22541/essoar.176279367.76125226/v1

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Wang, Guangyao et al (2025), Impact of Wave Interference on the Consistency Relations of Internal Gravity Waves near the Ocean Bottom, arXiv: 2511.03355

Wang, Wenbo et al (2025), Adaptive Sampling of Marine Submesoscale Features Using Gaussian Process Regression with Unmanned Platforms, Journal of Marine Science and Engineering, doi: 10.3390/jmse13112088

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Zhu, T., Liu, W. (2025), Evolving Southern Ocean overturning in warming climates, Nat Commun, doi: 10.1038/s41467-025-65389-5

Zinck, A.-S. P., Wouters, B., Jesse, F., and Lhermitte, S.(2025), Ocean-induced weakening of George VI Ice Shelf, West Antarctica, The Cryosphere, doi: 10.5194/tc-19-5509-2025

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