Self-sustained oscillations and global climate changes

Area of Science:

• Paleoclimatology
• Climate Dynamics
• Geochemistry

Background:

• Atmospheric CO2 and temperature changes over the last 5 million years present challenges to current climate models.
• Observed climate features, including the mid-Pleistocene transition and late Holocene cooling, are not fully explained by Milankovitch cycles.

Purpose of the Study:

• To investigate intrinsic mechanisms driving past climate dynamics.
• To develop a conceptual model explaining observed climate cycles beyond orbital forcing.
• To predict the climate system's response to a significant carbon dioxide pulse.

Main Methods:

• Development of a closed photochemical system model.
• Simulation of oscillations within the conceptual model under constant illumination.
• Adaptation of the model to the Earth system to explain paleoclimate features.
• Prediction of carbon dioxide pulse relaxation dynamics.

Main Results:

• A simple photochemical system can sustain intrinsic oscillations without external periodic forcing.
• The conceptual model successfully explains key features of past climate dynamics, including the mid-Pleistocene transition and Holocene cooling.
• The model identifies photosynthesis and the carbon cycle as primary drivers of climate change.
• A 1,000 PgC CO2 pulse removal is predicted to take one century, leading to a warmer, wetter climate but with intensified millennial-scale glaciation cycles.

Conclusions:

• Intrinsic oscillations within Earth's systems, driven by the carbon cycle and photosynthesis, are crucial for understanding past climate variability.
• The proposed model offers a new framework for climate research, moving beyond solely orbital forcing explanations.
• Future climate predictions indicate significant shifts in temperature, precipitation, and glaciation patterns in response to CO2 perturbations.