Publication Date:
2018-12-06
Description:
During the Last Glacial Maximum (LGM, ∼21,000 years ago) the cold climate was strongly tied to low atmospheric CO〈inf〉2〈/inf〉 concentration (∼190 ppm). Although it is generally assumed that this low CO〈inf〉2〈/inf〉 was due to an expansion of the oceanic carbon reservoir, simulating the glacial level has remained a challenge especially with the additional δ13C constraint. Indeed the LGM carbon cycle was also characterized by a modern-like δ13C in the atmosphere and a higher surface to deep Atlantic δ13C gradient indicating probable changes in the thermohaline circulation. Here we show with a model of intermediate complexity, that adding three oceanic mechanisms: brine induced stratification, stratification-dependant diffusion and iron fertilization to the standard glacial simulation (which includes sea level drop, temperature change, carbonate compensation and terrestrial carbon release) decreases CO〈inf〉2〈/inf〉 down to the glacial value of ∼190 ppm and simultaneously matches glacial atmospheric and oceanic δ13C inferred from proxy data. LGM CO〈inf〉2〈/inf〉 and δ13C can at last be successfully reconciled.
Type:
Article
,
PeerReviewed
Format:
text
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