Observations from research aircraft show that the Southern Ocean absorbs much more carbon from the atmosphere than it releases, confirming it is a very strong carbon sink and an important buffer for some of the effects of human-caused greenhouse gas emissions, according to a new NASA-supported study.
Recent research had raised uncertainty about just how much atmospheric carbon dioxide (CO2) these icy waters absorb. Those studies relied on measurements of ocean acidity – which increases when ocean water absorbs CO2 – taken by instruments that float in the ocean.
The new study, published in Science, used aircraft observations of CO2 to show that the Southern Ocean is a stronger carbon sink than previously thought, playing a significant role in lessening some of the impacts of greenhouse gases. Aircraft observations were collected over nearly a decade from 2009 to 2018 during three field experiments, including from NASA’s Atmospheric Tomography Mission (ATom) in 2016.
“Airborne measurements show a drawdown of carbon dioxide in the lower atmosphere over the Southern Ocean surface in summer, indicating carbon uptake by the ocean,” explained Matthew Long, lead author and a scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.
They found that the Southern Ocean absorbs significantly more CO2 in the Southern Hemisphere summer than it releases in the winter, making it a strong carbon sink. Data from the airborne campaigns also showed a larger amount of carbon absorbed by the Southern Ocean and smaller amount released than previous estimates using ocean acidity data. The findings highlight the importance of aircraft-based observations to understand carbon cycling.
Categories: Human interest