Quaternary Palaeoclimate Isotope Database (QPID)

Abstract

The ocean carbon cycle is a key driver of Earth’s climate, and yet there are still uncertainties about its influences and effects, and how it changes over time. One important remaining question is whether the temperature dependency of the rate of microbial respiration in the ocean has a significant impact on the efficiency of the biological pump. This process, which sequesters CO₂ away from the atmosphere for thousands of years, is a key uncertainty in models forecasting climate change into the future. Organic matter is decomposed by microbes as it sinks through the ocean, recycling nutrients and carbon back into the water column (a process termed remineralisation). The depth at which this remineralisation occurs has a direct effect on surface water carbon content and therefore atmospheric CO₂ concentrations. To investigate this, a new large database was compiled: the Quaternary Palaeoclimate Isotope Database (QPID), containing > 140000 measurements of planktic and benthic foraminiferal stable oxygen and carbon isotopes from 396 globally distributed marine sediment cores. This dataset was used to reconstruct the δ¹³C gradient, a proxy for nutrient content of the upper water column, in the Holocene and the LGM. No significant differences in gradient were found, either as a global average or in the Atlantic or Pacific Oceans. A lack of data due to sparse coverage, vital effects, and small expected signals may account for this null result. This work also includes reflections on the state of “big data” in palaeoceanography, and the current efforts aiming to improve the lack of standardisation and data availability which currently hinders large syntheses and meta analyses of palaeoclimate data.

Full text

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