Summit County Citizens Voice

Currents are pathways for carbon capture in Southern Ocean

The Southern Ocean is critical carbon sink.

By Summit Voice

SUMMIT COUNTY — Carbon isn’t uniformly absorbed in the Southern Ocean, but is drawn down and locked away from the atmosphere by plunging currents a thousand kilometers wide, according to a team of British and Australian scientists.

Winds, currents and massive whirlpools that carry warm and cold water around the ocean — known as eddies — create localized pathways, or funnels, for carbon to be stored.

The Southern Ocean is an important carbon sink in the world. About 40 percent of the annual global CO2 emissions absorbed by the world’s oceans are captured in this region.

“The Southern Ocean is a large window by which the atmosphere connects to the interior of the ocean below. Until now we didn’t know exactly the physical processes of how carbon ends up being stored deep in the ocean,” said Dr. Jean-Baptiste Sallée, of British Antarctic Survey. “Now that we have an improved understanding of the mechanisms for carbon draw-down we are better placed to understand the effects of changing climate and future carbon absorption by the ocean,” he said.

“Our study identifies these pathways for the first time and this matches well with observationally–derived estimates of carbon storage in the ocean interior,” said Australian researcher Dr. Richard Matear, explaining that the rate-limiting step in the anthropogenic carbon uptake by the ocean is the physical transport from the surface into the ocean interior.

Due to the size and remote location of the Southern Ocean, scientists have only recently been able to explore the workings of the ocean with the help of small robotic probes, known as Argo floats. In 2002, 80 floats were deployed in the Southern Ocean to collect information on the temperature and salinity. This unique set of observations spanning 10 years has enabled scientists to investigate this remote region of the world for the first time. The floats are just over a meter in length and dive to depths of 2,000 meters. Today, there are over 3,000 floats in the oceans worldwide providing detailed information used in oceanic climate models.

The team also analyzed temperature, salinity and pressure data collected from ship-based observations since the 1990s. The instrument used for this is called a CTD profiler which is a cluster of sensors taking measurements as it’s lowered deep down into the ocean to depths of more than 7,000 meters.

The research was published this week in the journal Nature Geoscience.

Filed under: climate and weather, Environment, global warming Tagged: | British Antarctic Survey, carbon cycle, Carbon sink, climate, Commonwealth Scientific and Industrial Research Organisation, global warming, Nature Geoscience, oceans, Southern Ocean