Magnitude of the Suess Effect in North Atlantic - a Study of Foraminifera and Transient Tracer Simulations

The Suess Effect is the decrease of $\delta^{13}$C in the atmosphere due to the burning of fossil fuels. The recent decrease in $\delta^{13}$C in the deep sea due to uptake of carbon has been measured in samples taken on hydrographic surveys, although these surveys only provide snapshots of deep sea $\delta^{13}$C. The long-term decrease in $\delta^{13}$C has been estimated using modern hydrographic properties, but there are no direct measurements. Here we present records of $\delta^{13}$C from benthic and planktonic foraminifera, collected south of Iceland in the North Atlantic Ocean. The cores have high accumulation rates and, based on radiocarbon, modern core tops. We find a monotonic decreasing trend since 1850 that is significant in two out of the three benthic records we have generated. A tracer simulation, with Transit Time Distribution and Equilibrium Time Distribution generated from previous tracer modeling studies, predicts a trend that is similar to our observations at the core sites. The presence of the Suess Effect in some of the cores is consistent with previous estimates on the uptake of anthropogenic CO${}_2$ in the newly formed North Atlantic Deep Water.