Paleocene/Eocene carbon feedbacks triggered by volcanic activity.

Area of Science:

• Paleoclimatology
• Geochemistry
• Earth System Science

Background:

• The Paleocene-Eocene Thermal Maximum (PETM) (~56 million years ago) was a period of rapid global warming and significant carbon release.
• The precise trigger and involvement of multiple carbon reservoirs during the PETM remain debated.
• Previous studies suggest volcanic activity but lack direct evidence for the trigger and subsequent carbon release mechanisms.

Purpose of the Study:

• To identify the trigger of the Paleocene-Eocene Thermal Maximum (PETM) and investigate the role of multiple carbon reservoirs.
• To provide direct geochemical evidence for volcanism and carbon release during the PETM.
• To explore the concept of Earth system 'tipping points' in the context of past climate change.

Main Methods:

• Analysis of mercury (Hg) to organic carbon (Corg) ratios in two North Sea sedimentary cores.
• Using Hg/Corg as a proxy for volcanism to reconstruct volcanic activity preceding and during the PETM.
• Correlation of geochemical data with existing paleoclimate records.

Main Results:

• Elevated Hg/Corg ratios were found preceding and within the early PETM, indicating pulsed volcanism from the North Atlantic Igneous Province.
• This volcanism likely initiated the PETM and sustained elevated atmospheric CO2 levels.
• A concurrent mercury low at the PETM onset suggests additional carbon reservoirs were destabilized by initial warming.

Conclusions:

• Pulsed volcanism from the North Atlantic Igneous Province was a likely trigger for the PETM.
• The PETM involved at least two distinct carbon release phases, with volcanism initiating the event and subsequent warming triggering other reservoirs.
• The findings support the existence of climate 'tipping points' that can lead to cascading carbon releases and extreme warming events.