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Over the past two and a half centuries, the ocean has absorbed approximately 25% of humankind’s carbon dioxide (CO2) emissions, reducing the accumulation of greenhouse gases in the atmosphere and slowing the rate of climate change. While the uptake of CO2 by the ocean reduces the amount of warming the emissions would otherwise cause, it also increases the acidity of seawater, endangering marine organisms and ocean health. Long-term monitoring and scientific analysis of ocean carbon fluxes and inventories is critical for understanding how this important sink for anthropogenic CO2 functions, to determine if ocean uptake of CO2 will keep pace with emissions, and how we can best anticipate, mitigate, and adapt to potential future changes.

NOAA’s Global Ocean Carbon Network provides long-term observations of carbon from the sea surface to the ocean interior at a range of spatial and temporal scales. This network helps address the key socioeconomic and scientific questions relating to the fate and impacts of the changing global carbon cycle on society and the environment.

Surface Ocean Carbon
Knowledge of interannual and decadal changes in oceanic CO2 uptake are essential for assessing the feedbacks between climate change and the ocean carbon cycle. The surface ocean pCO2 network  provides information on the role of shorter-term variability on the global carbon system. This network measures the temperature, salinity, and pCO2 in surface water and air from Ships of Opportunity (SOOP), including research and commercial vessels, and autonomous platforms to determine the carbon exchange between the ocean and atmosphere. These observations are used to quantify the amount of atmospheric CO2 sequestered by the ocean on seasonal scales, document changes in the surface ocean carbon chemistry, and evaluate the variability in air-sea fluxes to provide meaningful projections of future atmospheric CO2 levels.

Ocean Interior Carbon
Ship-based hydrography remains the only method for obtaining high-quality, high spatial and vertical resolution measurements of a suite of physical, chemical, and biological parameters over the full water column on a global scale. U.S. GO-SHIP, part of the international GO-SHIP network of sustained hydrographic sections, collects ocean interior carbon measurements to determine changes in anthropogenic CO2 inventories throughout the water column, including at depths greater than two kilometers below the current depth of core Argo floats.