Figure 5. Comparison of ΔR data with other AMOC-sensitive proxy records.

Shell-based ΔR values (this study; solid orange circles) and sediment-based ΔR values24 (solid squares; MD99-2275 and MD99-2273) are compared with Gulf Stream transport estimates1 (blue) in the Florida Straits and SST values from within the Arctic Ocean10 (marine sediment record from Fram Strait off western Svalbard, 79°N; green) during the last millennium. More positive ΔR values are representative of Arctic-derived water masses, whereas less positive ΔR values are indicative of Atlantic-derived surface waters24. Relatively warmer SST values in Fram Strait indicate a strong Atlantic inflow to the Arctic, while relatively cool SST values likely represent a weak Atlantic inflow to the Arctic10. The errors in the Marine09 ¹⁴C value28 and the AMS ¹⁴C measurement were propagated as random errors yielding a total ΔR_shell error. Tephra layers in marine sediment cores (MD99-2275 and MD99-2273) are shown along the bottom (solid black squares) to illustrate the age control for sediment sequences north of Iceland24. The age/depth models for the Fram Strait and Gulf Stream data are based on linear interpolation between calibrated AMS ¹⁴C ages, and the Fram Strait data have an age error of about ±30 to 50 years (see ref. 10 for the full SST record and details); the Gulf Stream data have a possible age error of about ±50 years1. The horizontal grey bar represents the approximate regional timing of the MCA/LIA transition in the marine environment (that is, North Icelandic shelf) noted by refs 24, 25, 26.