Fig. 1

Maps showing expected δ¹⁸O_aragonite range caused only by temperature between the surface and 400 m depth in the global ocean. Locations for thermocline data used in simulation are indicated by different shapes. White areas near continents are shelves where the seafloor is shallower than 400 m. a Water column structure for August, displaying near-peak northern hemisphere summer temperatures. b Water column structure for February, displaying near-minimum northern hemisphere winter temperatures. The spatially extensive influence of seasonality in the mid-Latitudes is most apparent in the North Atlantic.