A stable hothouse triggered by a tipping mechanism.

Area of Science:

• Climate science
• Complex systems analysis
• Earth system modeling

Background:

• Earth's climate system exhibits nonlinear dynamics with potential tipping points.
• Palaeoclimatic data indicate past shifts to extreme states like 'hothouse Earth'.
• A specific mechanism for sudden transitions to warmer stable states remains elusive.

Purpose of the Study:

• To present a novel tipping mechanism for a hothouse Earth state.
• To introduce and utilize a coupled temperature-carbon-vegetation (TCV) model.

Main Methods:

• Development of a TCV model integrating an energy balance model (EBM) with CO2 dynamics and vegetation changes.
• Simulation of climate dynamics under high-emission scenarios.
• Comparison of model outputs with observational data and Intergovernmental Panel on Climate Change (IPCC)-class global climate models (GCMs).

Main Results:

• The TCV model demonstrates a new tipping mechanism leading to a hothouse Earth.
• Model simulations align with current observations and GCMs before the tipping point.
• Key tipping drivers identified: temperature-albedo feedback from glacial microalgae and reduced carbon absorption due to vegetation adaptation limits.

Conclusions:

• A specific mechanism for a sudden shift to a significantly warmer climate state has been identified.
• The TCV model provides insights into critical transitions in the Earth's climate system.
• Understanding these tipping mechanisms is crucial for predicting and potentially mitigating irreversible climate change.