Recent research spearheaded by the University of East Anglia (UEA) and Plymouth Marine Laboratory (PML) has revealed that the Southern Ocean CO2 sink absorbs significantly more carbon dioxide than previously estimated. This groundbreaking study, utilizing direct air-sea CO2 flux measurements, shows that the ocean around Antarctica absorbs 25% more CO2, suggesting that past models and indirect methods like shipboard data have substantially underestimated the ocean’s capacity for carbon capture.
This finding is crucial because the Southern Ocean CO2 sink plays a vital role in regulating the Earth’s climate by absorbing CO2 emitted from human activities. Traditionally, the estimates of this CO2 uptake have been made using shipboard measurements and data from devices like profiling floats or drawn from global ocean biogeochemistry models. However, these methods have led to significant discrepancies in the estimated magnitude and variability of the ocean’s carbon absorption capabilities.
To address these discrepancies, the research utilized an advanced method called eddy covariance, which involves flux systems mounted on ships’ foremasts to measure CO2 exchange directly. Conducted over seven research cruises, this method provided more accurate and immediate data, contrasting sharply with the weaker estimates derived from float data and model simulations. The results, published in the journal Science Advances, highlight the summer season’s strong Southern Ocean CO2 sink, challenging earlier assumptions about its effectiveness and pointing out the underestimation of its CO2 absorption capacity.
Dr. Yuanxu Dong, the lead author from UEA’s Centre for Ocean and Atmospheric Sciences, stressed the importance of this research for accurate climate assessment. He highlighted that the Southern Ocean CO2 sink is one of the most uncertain regions in terms of CO2 sink capacity estimates. The study’s findings advocate for temperature adjustments and higher-resolution reconstruction and modeling in future estimates to enhance the accuracy of global climate models.
The research team, including scientists from the Alfred Wegener and Max Planck Institutes in Germany, the Flanders Marine Institute in Belgium, and the University of Hawai’i in the US, further explored the implications of these findings. They utilized the eddy covariance observations to reassess and validate existing data sets, shedding light on potential improvements in observational methods and data interpretation.
Despite the advancements, the study acknowledges the challenges in expanding CO2 flux observations, particularly the lack of winter data due to the difficulty of accessing the region during colder months. This gap is partially addressed by floats, but more comprehensive measurements, including the deployment of buoys and sail drones, are essential for a fuller understanding of the Southern Ocean CO2 sink throughout the year.
In conclusion, the study calls for sustained and expanded funding for surface ocean CO2 measurements and their integration into the Surface Ocean CO2 Atlas (SOCAT). Such efforts are vital not only for refining our understanding of the Southern Ocean’s role in global carbon dynamics but also for informing climate policy and supporting international climate monitoring initiatives like the World Meteorological Organization’s Global Greenhouse Gas Watch.
www.scitechdaily.com/mighty-carbon-sink-southern-ocean-absorbing-25-more-co2-than-previously-thought/