Evidence for a biological pump driver of atmospheric CO 2 rise during Heinrich Stadial 1
2016; American Geophysical Union; Volume: 43; Issue: 23 Linguagem: Inglês
10.1002/2016gl070723
ISSN1944-8007
AutoresJ. E. Hertzberg, David C Lund, Andreas Schmittner, Alexandra Skrivanek,
Tópico(s)Isotope Analysis in Ecology
ResumoAbstract The initial trigger of the atmospheric CO 2 rise during Heinrich Stadial 1 (HS1: 14.5–17.5 kyr B.P.) remains elusive. We present a compilation of four paired surface and intermediate‐depth foraminiferal δ 13 C records to test whether reduced biological pump efficiency led to the initial CO 2 rise during the last deglaciation. Surface ocean δ 13 C decreased across HS1 while intermediate‐depth δ 13 C increased, leading to a reduction in the upper ocean δ 13 C gradient. Our compilation also suggests the δ 13 C gradient increased during the Bølling‐Allerød (12.9–14.5 kyr B.P.) and decreased during the Younger Dryas (YD: 11.7–12.9 kyr B.P.). The HS1 and YD data are consistent with reduced biological export of isotopically light carbon from the surface ocean and its remineralization at depth. Our results support the idea that a weaker Atlantic Meridional Overturning Circulation decreased biological pump efficiency by increasing the overall fraction of preformed nutrients in the global ocean, leading to an increase in atmospheric CO 2 .
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