Variations in mid-ocean ridge CO2 emissions driven by glacial cycles

TL;DR

This study models how glacial cycles and sea-level changes influence mid-ocean ridge CO2 emissions, predicting up to 12% variations over the past million years, with implications for understanding climate-volcano interactions.

Contribution

It introduces a simplified transport model linking sea-level changes to CO2 emissions at mid-ocean ridges, highlighting the lag and sensitivity to mantle permeability and spreading rate.

Findings

Global mid-ocean ridge CO2 emissions average 53 Mt/yr.

Sea-level drops increase CO2 emissions with a 100 kyr lag.

Predicted emissions vary by up to 12% over glacial cycles.

Abstract

The geological record shows links between glacial cycles and volcanic productivity, both subaerially and at mid-ocean ridges. Sea-level-driven pressure changes could also affect chemical properties of mid-ocean ridge volcanism. We consider how changing sea-level could alter the CO2 emissions rate from mid-ocean ridges, on both the segment and global scale. We develop a simplified transport model for a highly incompatible element through a homogenous mantle; variations in the melt concentration the emission rate of the element are created by changes in the depth of first silicate melting. The model predicts an average global mid-ocean ridge CO2 emissions-rate of 53 Mt/yr, in line with other estimates. We show that falling sea level would cause an increase in ridge CO2 emissions with a lag of about 100 kyrs after the causative sea level change. The lag and amplitude of the response are sensitive to mantle permeability and plate spreading rate. For a reconstructed sea-level time series of the past million years, we predict variations of up to 12% (7 Mt/yr) in global mid-ocean ridge CO2 emissions. The magnitude and timing of the predicted variations in CO2 emissions suggests a potential role for ridge carbon emissions in glacial cycles.