Evidence for massive methane hydrate destabilization during the penultimate interglacial warming.

Area of Science:

• Paleoclimatology
• Marine Geology
• Climate Science

Background:

• Methane hydrates in marine sediments are sensitive to ocean warming.
• Destabilization releases methane, amplifying global warming.
• Understanding intermediate water warming is crucial for climate change assessment.

Purpose of the Study:

• Reconstruct past ocean thermal structure and methane oxidation.
• Investigate intermediate water warming linked to Atlantic meridional overturning circulation (AMOC) weakening.
• Provide a paleoanalog for current global warming trends.

Main Methods:

• Analyzed sediment cores from the eastern equatorial Atlantic (Gulf of Guinea).
• Reconstructed water column thermal structure over 1,300 m.
• Examined foraminifer shells for carbon isotope (δ¹³C) signatures.

Main Results:

• Documented a 6.8°C intermediate water warming event 126,000–125,000 years ago.
• Observed significant methane hydrate destabilization, evidenced by a large negative δ¹³C excursion.
• Linked warming and hydrate destabilization to a modest AMOC weakening episode.

Conclusions:

• The penultimate interglacial warming event caused substantial methane release.
• This provides a critical paleoanalog for modern climate change and methane hydrate stability.
• Intermediate water warming poses a significant risk for climate feedbacks.