Sea level fall during glaciation stabilized atmospheric CO<sub>2</sub> by enhanced volcanic degassing.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28681844.
- Also identified by DOI 10.1038/ncomms15867 and PMC identifier 5504290.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Paleo-climate records and geodynamic modelling indicate the existence of complex interactions between glacial sea level changes, volcanic degassing and atmospheric CO<sub>2</sub>, which may have modulated the climate system's descent into the last ice age. Between ∼85 and 70 kyr ago, during an interval of decreasing axial tilt, the orbital component in global temperature records gradually declined, while atmospheric CO<sub>2</sub>, instead of continuing its long-term correlation with Antarctic temperature, remained relatively stable. Here, based on novel global geodynamic models and the joint interpretation of paleo-proxy data as well as biogeochemical simulations, we show that a sea level fall in this interval caused enhanced pressure-release melting in the uppermost mantle, which may have induced a surge in magma and CO<sub>2</sub> fluxes from mid-ocean ridges and oceanic hotspot volcanoes. Our results reveal a hitherto unrecognized negative feedback between glaciation and atmospheric CO<sub>2</sub> predominantly controlled by marine volcanism on multi-millennial timescales of ∼5,000-15,000 years.