| The cause of the initial rise in atmospheric CO2 during the last deglaciation remains unknown. Coincident with the rising atmospheric CO2, the δ13C of atmospheric CO2 decreased by ~0.3‰ during Heinrich Stadial 1 (HS1: 14.5-17.5 kyr BP), which requires the input of carbon from an isotopically light reservoir. The light carbon signal in the atmosphere occurred concurrently with the carbon isotope minimum, or a decrease in surface ocean δ13C of ~0.5‰, suggesting the two phenomena are related. The leading hypotheses explaining the δ13C minimum are (1) enhanced ventilation of 13C-depleted abyssal water in the Southern Ocean which in turn caused low δ13C values in the surface ocean and atmosphere, and (2) a reduction in the Atlantic Meridional Overturning... |
