Fig. 3

Noëlaerhabdaceae coccolith morphometrics, and their response to excepted [CO_2aq] at site MD07-3088 over the last deglaciation. a–d Relationships between coccolith mass (pg) and coccolith area (a), thickness (b), as well as coccolith aspect ratio (AR_L)²⁸ (c) and SN thickness²⁷ (d) (Methods section). e–i Coccolith morphometric changes during the deglaciation: e mass (pg), f area (μm²), g thickness (µm), h–i SN²⁷ and AR_L²⁸ indices (Methods section). Coccolith mass show no relationship with coccolith area, but clear positive relationships with size normalized coccolith mass indices AR_L and SN which indicates that the mass of coccoliths typically increases in proportion with their thickness. Therefore, changes in coccolith mass document changes in the degree of coccolith calcification (i.e. PIC/POC ratio). Obviously, the Noëlaerhabdaceae coccolith mass increases observed during enhanced SO upwelling associated with higher sea surface fertility conditions (yellow shading), document increased coccosphere calcite quota in response to SSW [CO_2aq] rises during HS1 and YD