Following the C: A Quick Introduction to Tracking Ocean Carbon

Earthzine2016 Monthly Focus Topics, Original, Themed Articles

With the rise in atmospheric concentrations of carbon dioxide (CO2), carbon‰Ûªs role in ocean chemistry and biology is being augmented. New tracking and modeling techniques help to reveal how a changing atmosphere may impact the oceans.

A simple diagram of the ocean carbon cycle, showing uptake from the atmosphere, longterm storage in deepsea sediments, and release during upwelling. Image Credit: Hannes Grobe, 2016

A simple diagram of the ocean carbon cycle, showing uptake from the atmosphere, longterm storage in deepsea sediments, and release during upwelling. Image Credit: Hannes Grobe, 2016

Carbon plays a leading role in ocean chemistry and biology, a role currently augmented by rising atmospheric concentrations of carbon dioxide (CO2). Tracking the rate at which carbon is taken up by the ocean, its ecological impacts, and how it is distributed throughout the oceans will be critical to understanding what these changes mean for ocean health.

During the last century, human industrial activities, such as the burning of fossil fuels, deforestation, and cement production have increased the concentration of CO2 in the Earth‰Ûªs atmosphere by roughly 25 percent. That 80 parts-per-million increase of carbon dioxide only represents a portion of the carbon released though. The rest is taken up by plants during photosynthesis or dissolved into the ocean when surface water mixes with the air. åÊThe ocean, therefore, acts as a significant sink for global carbon: it is estimated that of anthropogenic CO2 added to the atmosphere, the ocean takes up around 48 percent.

Such a large shift in the chemical balance of the ocean has repercussions for ocean life. Ocean acidification, a consequence of increased oceanic carbon dioxide levels, is associated with ecological impacts such as increased stressing in animals such as corals, snails, and oysters that rely on the formation of calcium carbonate shells or skeletons.

In spite of the widespread impacts ocean acidification could have, knowledge about ocean carbon is still limited. Efforts to improve that knowledge stretch from beyond the stratosphere down to the depths of the ocean.

In space, satellites such as those in NASA‰Ûªs GRACE satellite mission provide data on surface ocean currents as well as changes in atmospheric pressure that signal changes in deeper ocean currents.

Data from space are complemented by data collected from the surface of the ocean. In the case of the GRACE mission, these data are often compared with observations from the RAPID network of ocean buoys managed by the National Oceanography Centre in the United Kingdom.

Measurements also are taken below the ocean surface. In recent years, groups like the National Oceanic and Atmospheric Administration‰Ûªs Pacific Marine Environmental Laboratory (PMEL) have begun employing underwater drones to gather information about ocean chemistry from beneath the waves.

Research of this type helps scientists generate models of current ocean carbon cycles and project how these cycles may change in the future. Parallel to studies on ocean carbon tracking are studies on ocean carbon impacts and ocean carbon cycles on a local ecosystems level. To learn more about specific studies associated with ocean carbon, keep an eye out for Earthzine‰Ûªs upcoming monthly focus topic articles.