Cenozoic evolution of deep ocean temperature from clumped isotope thermometry

Area of Science:

• Paleoclimatology
• Geochemistry

Background:

• Understanding past climate states is essential for predicting future climate change impacts from greenhouse gas emissions.
• Oxygen isotope-based reconstructions are classical methods for determining past ocean temperatures.

Observation:

• Deep ocean temperatures were reconstructed for the past 65 million years using clumped isotope thermometry.
• Temperature estimates were derived from the deep Atlantic Ocean.

Findings:

• Clumped isotope thermometry yielded significantly warmer deep ocean temperature estimates compared to oxygen isotope reconstructions.
• This discrepancy suggests potential influences of deep ocean pH and seawater oxygen isotope composition on previous Cenozoic records.
• Unrecognized large fluctuations in deep ocean temperature were identified during the Early Eocene greenhouse warming events.

Implications:

• Results necessitate a reevaluation of Cenozoic ocean temperature history.
• A revised understanding is crucial for accurately assessing climate responses to tectonic events and greenhouse gas forcing.
• This research provides a more accurate framework for future climate change predictions.