Nitrogen Release From Permafrost Thaw May Partially Offset Future Soil Carbon Losses

Area of Science:

• Earth System Science
• Climate Science
• Ecology

Background:

• Permafrost thaw releases significant soil carbon, impacting atmospheric greenhouse gas levels.
• Nitrogen release from thawing permafrost is a critical, yet understudied, feedback mechanism.
• Understanding permafrost-climate interactions is vital for accurate climate change projections.

Purpose of the Study:

• To quantify the impact of nitrogen release from thawing permafrost on the carbon cycle.
• To assess the role of nitrogen availability in mitigating carbon loss from permafrost regions.
• To improve Earth system models by incorporating permafrost and nitrogen cycle dynamics.

Main Methods:

• Utilized a novel Earth system model (IPSL-Perm-LandN) with integrated permafrost physics and nitrogen cycle.
• Performed idealized climate change simulations isolating CO2 fertilization, climate change, and nitrogen availability impacts.
• Simulated key permafrost processes including soil freezing, organic matter insulation, and cryoturbation.

Main Results:

• Nitrogen release from thawing permafrost offset over 80% of climate-induced soil carbon losses in the model.
• The permafrost region remained a net carbon sink due to CO2 fertilization and increased nitrogen availability.
• A significant negative contribution to the global carbon-climate feedback parameter ($\gamma$) was prevented.

Conclusions:

• The nitrogen feedback significantly reduces the net carbon release from thawing permafrost.
• Permafrost regions may act as carbon sinks under future climate change, driven by CO2 and nitrogen availability.
• Uncertainty remains regarding the magnitude of vegetation carbon uptake, necessitating careful consideration in climate mitigation strategies.