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June 30, 2021 Toste Tanhua; Siv K. Lauvset; Nico Lange; Are Olsen; Marta Álvarez; Stephen C Diggs; Henry C. Bittig; Peter J. Brown; Brendan R. Carter; Brendan R. Carter; Leticia Cotrim da Cunha; Richard A. Feely; Mario Hoppema; Masao Ishii; Emil Jeansson; Alex Kozyr; Akihiko Murata; Fiz F. Pérez; Benjamin Pfeil; Carsten Schirnick; Reiner Steinfeldt; Maciej Telszewski; Bronte Tilbrook; Anton Velo; Rik Wanninkhof; Eugene Burger; Kevin D. O'Brien; Kevin D. O'Brien; Robert M. Key


The ocean is mitigating global warming by absorbing large amounts of excess carbon dioxide from human activities. To quantify and monitor the ocean carbon sink, we need a state-of-the-art data resource that makes data submission and retrieval machine-compatible and efficient.

Human activities such as combustion of fossil fuel, land use change, and cement production increased the atmospheric carbon dioxide (CO2) concentration to 418 ppm in April 2021. This level is almost 50% higher than at the beginning of the industrial age. The greenhouse effect of atmospheric CO2 and other gases has led to significant warming and increased stratification in the ocean, and has consequences for ecosystems and marine ecosystem services. Notably, atmospheric CO2 concentrations would now be around another 76 ppm higher than current levels1 if the ocean had not taken up a significant fraction of our emissions from the atmosphere2.

The ocean is one of the largest carbon pools on the planet, second only to the Earth’s crust. The ocean contains about 38,000 Gigatonnes of carbon and thereby dwarfs the cumulative emissions of fossil CO2 since the Industrial Revolution from fossil fuel combustion (about 440 GtC to 2019) and land-use change (about 210 GtC)1. As such, the accumulation rate of carbon in the surface ocean of about 1 µmol kg−1 year−1 driven by anthropogenic CO2 emissions is much smaller than the natural variations in dissolved inorganic carbon content, over a range of 500 µmol kg−1 regionally and 100 µmol kg−1 seasonally3. Thus, any emission-driven trends in ocean carbon concentrations or changes in biogeochemical cycles are expressed amid large natural variability in these seawater properties across a range of spatial and temporal scales. Accurately quantifying a small change against a large and variable background requires precise and accurate measurements made over decades.

The GLobal Ocean Data Analysis Project (GLODAP)4,5, initiated in 2004 and subsequently updated6,7,8, has been instrumental in delivering carbon-relevant interior ocean data that support well-quantified estimates of the ocean carbon sink. The project delivers near-global data coverage; standardized quality control procedures; a high degree of internal consistency; common data formats; and open and free access to the available data. Compared to its first version, the GLODAP data inventory has more than tripled in size (Fig. 1). In order to continue to serve its purpose, GLODAP needs to advance both its data ingestion systems and its data extraction systems to become more streamlined and automated. In order to decrease the amount of routine manual work as well as the potential for errors, data submission workflows must become uniform, semi-automated, and compatible with machine-learning techniques for quality control. The data extraction system also needs to accommodate a wider range of filtering to fine-tune requests from users.

Publication DOI: https://doi.org/10.1038/s43247-021-00209-44