Figure 4: Proxy records of sediment core JM-FI-19PC plotted with North Greenland Ice Core Project δ18O values.
From: Episodic release of CO2 from the high-latitude North Atlantic Ocean during the last 135 kyr
(a) ΔpCO2sea-air. (b) Cd/Ca measured in N. pachyderma. (c) δ13C measured in N. pachyderma. (d) δ13C measured in organic matter (δ13Corg) (ref. 16). (e) concentration of brassicasterol16. (f) concentration of dinosterol16. (g) C25 isoprenoid lipid (IP25) (ref. 16). High concentration of IP25 suggests presence of seasonal sea ice, whereas absence of IP25 suggests either permanent sea-ice cover (when the concentration of sterols is low) or open ocean conditions (when the concentration of sterols is high) (see Hoff et al.16 for details). Note the break in the y-axes of plots e–g. (h) shallow subsurface (black) and bottom water (grey) temperature14,15. Bottom water temperatures are based on Mg/Ca in the benthic foraminiferal species Melonis barleeanus (triangles) and Cassidulina neoteretis (squares). Shallow subsurface temperatures are based on Mg/Ca in N. pachyderma. (i) North Greenland Ice Core Project (NGRIP) ice core δ18O values28,67. Red stars on the x-axis indicate tephra layers that are common to sediment core JM11-FI-19PC and Greenland ice cores (Supplementary Fig. 1).
