Upwelling index from IODP Site 323-U1343

High latitude deep water upwelling has the potential to control global climate over glacial timescales through the biological pump and ocean-atmosphere CO2 exchange. However, there is currently a lack of continuous long nutrient upwelling records with which to assess this mechanism. This study presents a new high resolution long sedimentary nitrogen isotope record from IODP Site U1343 in the Bering Sea green belt, where we assume that the sedimentary bulk N is a representation of total macronutrient utilisation. By accounting for changes in export production, we normalise the opal mass accumulation rate (MAR) and produce the first high latitude record of nutrient delivery from deep to surface water (termed the “upwelling index”). By semi-quantitatively assessing the offset between the opal MAR and N in this way, we constrain the impact of local growth rate and iron supply, to reveal long-term variability in macronutrient supply from deep water upwelling.