Research aircraft reveal a surprisingly strong Southern Ocean carbon sink

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Having much better information about how nature’s carbon cycle is working, before attempting to apply random expensive schemes of uncertain impact to try and alter it, would surely be a sound approach, as the researchers suggest. Surprises might not be welcome ones.
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The Southern Ocean is a significant carbon sink says, absorbing a large amount of the excess carbon dioxide emitted into the atmosphere by human activities, according to a new study led by the National Center for Atmospheric Research (NCAR).

The findings provide clarity about the role the icy waters surrounding Antarctica play in buffering the impact of increasing greenhouse gas emissions, after research published in recent years suggested the Southern Ocean might be less of a sink than previously thought.

The new study, published this week in the journal Science, makes use of observations from research aircraft flown during three field projects over nearly a decade, as well as a collection of atmospheric models, to determine that the Southern Ocean takes up significantly more carbon than it releases.

The research also highlights the power that airborne observations have to reveal critical patterns in the global carbon cycle.

“You can’t fool the atmosphere,” said NCAR scientist Matthew Long, the paper’s lead author. “While measurements taken from the ocean surface and from land are important, they are too sparse to provide a reliable picture of air-sea carbon flux. The atmosphere, however, can integrate fluxes over large expanses. Airborne measurements show a drawdown of CO2 in the lower atmosphere over the Southern Ocean surface in summer, indicating carbon uptake by the ocean.”

Uncertainty about the role of the Southern Ocean

Once human-produced emissions of CO2—from burning fossil fuels and other activities—enter the atmosphere, some of the gas is taken up by plants and some is absorbed into the ocean. While the overall concentration of CO2 in the atmosphere continues to increase, causing the global temperature to rise, these land and ocean “sinks” slow the effect.

A more precise understanding of where carbon sinks exist, how big they are, and how they may be changing as society continues to emit more CO2 is crucial to projecting the future trajectory of climate change.

It is also necessary for evaluating the impact of potential emission reduction measures and CO2 removal technologies.

Scientists have long thought that the Southern Ocean is an important carbon sink. In the region around Antarctica, cold water from the deep ocean is transported to the surface. This upwelling water may not have seen the surface of the ocean for hundreds of years—but once in contact with the atmosphere, it’s able to absorb CO2 before sinking again.

Measurements of CO2 and related properties in the ocean suggest that 40 percent of all human-produced CO2 now stored in the ocean was originally taken up by the Southern Ocean.

But measuring the actual flux at the surface—the back and forth exchange of CO2 between the water and the overlying air throughout a year—has been challenging.

Continued here.

via Tallbloke’s Talkshop

December 3, 2021, by oldbrew