Why We Observe the Ocean

Ocean Carbon Uptake

• Measuring uptake of atmospheric carbon dioxide (CO₂) by the ocean is necessary to better understand both the extent to which the ocean sequesters CO₂ and how cycling among carbon reservoirs varies on seasonal-to-decadal time scales.

• Ocean-atmosphere exchange of CO₂ by diffusion across the ocean surface results in ocean uptake of about a quarter of all anthropogenic CO₂ emissions. As such, the ocean constitutes one of the largest sinks for the greenhouse gas most responsible for global climate change.

• Air-sea exchange of CO₂ is a sensitive function of temperature, wind speed, sea surface roughness, ocean vertical mixing, precipitation, and local biological activity in the ocean. As a consequence, ocean uptake of CO₂ varies greatly with season and location; indeed, some regions of the ocean are net sources while others are net sinks of CO₂. Observations are required to identify these regions and the ocean processes that control their behavior.

• Large-scale patterns of natural climate variability, such as El Niño, are known to significantly alter regional air-sea exchange of CO₂.

• In order to project the future capacity of the ocean to sequester anthropogenic CO₂ emissions it is necessary to elucidate the processes that influence air-sea exchange rates and to better understand how those processes might vary as the Earth’s climate changes.

• A consequence of ocean uptake of CO₂ is acidification of the ocean, with potentially significant impacts on marine biota.