Open AccessCarbon isotope minima in the South Atlantic during the last deglaciation: evaluating the influence of air-sea gas exchange
Author(s) -
David C Lund,
J. E. Hertzberg,
Matthew Lacerra
Publication year - 2019
Publication title -
environmental research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.37
H-Index - 124
ISSN - 1748-9326
DOI - 10.1088/1748-9326/ab126f
Subject(s) - geology , younger dryas , oceanography , deglaciation , stadial , benthic zone , climatology , plankton , carbon cycle , isotopes of carbon , holocene , total organic carbon , chemistry , ecosystem , ecology , environmental chemistry , biology
Carbon isotope minima were a ubiquitous feature in the mid-depth (1.5–2.5 km) Atlantic during Heinrich Stadial 1 (HS1, 14.5–17.5 kyr BP) and the Younger Dryas (YD, 11.6–12.9 kyr BP), with the most likely driver being collapse of the Atlantic Meridional Overturning Circulation (AMOC). Negative carbon isotope anomalies also occurred throughout the surface ocean and atmosphere, but their timing relative to AMOC collapse and the underlying drivers have remained unclear. Here we evaluate the lead-lag relationship between AMOC variability and surface ocean δ 13 C signals using high resolution benthic and planktonic stable isotope records from two Brazil Margin cores (located at 1.8 km and 2.1 km water depth). In each case, the decrease in benthic δ 13 C during HS1 leads planktonic δ 13 C by 800 ± 200 years. Because the records are based on the same samples, the relative timing is constrained by the core stratigraphy. Our results imply that AMOC collapse initiates a chain of events that propagates through the oceanic carbon cycle in less than 1 kyr. Direct comparison of planktonic foraminiferal and atmospheric records implies a portion of the surface ocean δ 13 C signal can be explained by temperature-dependent equilibration with a 13 C-depleted atmosphere, with the remainder due to biological productivity, input of carbon from the abyss, or reduced air-sea equilibration.