Multidecadal changes in biology influence the variability of the North Atlantic carbon sink

• Published in: Environmental Research Letters
• Main Authors: Ostle, C, Landschützer, P, Edwards, M, Johnson, M, Schmidtko, S, Schuster, U, Watson, AJ, Robinson, C
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2022
• Subjects: multidecadal; biology; influence; variability; North Atlantic; carbon sink; warming; Sea ice
• Online Access: http://hdl.handle.net/10871/131906; https://doi.org/10.1088/1748-9326/ac9ecf

This is the final version. Available from IOP Publishing via the DOI in this record. Data availability statement: The data that support the findings of this study are available upon reasonable request from the authors. The datasets that support the findings of this study are available through the following listed websites; the carbon observation data were obtained from the SOCAT (www.socat.info), the biological data were obtained from the CPR Survey (www.cprsurvey.org), SST data were obtained from the ICOADS (1◦ enhanced data, www.esrl. noaa.gov/psd/data/gridded/data.coads.1deg.html). The satellite derived estimate of sea surface chl-a was obtained from the OC-CCI dataset version 4.1 (esa-oceancolour-cci.org) [35]. MLD was obtained from the global ocean and sea-ice reanalysis products (ORAS5: Ocean Reanalysis System 5) prepared by the European Centre for Medium-Range Weather Forecasts (ECMWF www.ecmwf.int/node/18519) [37]. The North Atlantic Ocean is the most intense marine sink for anthropogenic carbon dioxide (CO2) in the world’s oceans, showing high variability and substantial changes over recent decades. However, the contribution of biology to the variability and trend of this sink is poorly understood. Here we use in situ plankton measurements, alongside observation-based sea surface CO2 data from 1982 to 2020, to investigate the biological influence on the CO2 sink. Our results demonstrate that long term variability in the CO2 sink in the North Atlantic is associated with changes in phytoplankton abundance and community structure. These data show that within the subpolar regions of the North Atlantic, phytoplankton biomass is increasing, while a decrease is observed in the subtropics, which supports model predictions of climate-driven changes in productivity. These biomass trends are synchronous with increasing temperature, changes in mixing and an increasing uptake of atmospheric CO2 in the subpolar North Atlantic. Our results highlight that phytoplankton play a significant role in the variability as ...