Shifting winds weakened the recent Southern Ocean CO2 absorption

Graphic © L. Keppler

In a new study, Lydia Keppler and Dr Peter Landschützer from department “The Ocean in the Earth System” at the Max Planck Institute for Meteorology (MPI-M) find that the carbon dioxide (CO2) absorption in the Southern Ocean weakened between 2012 and 2016. The study links shifts in regional winds to this reduced carbon uptake.

Similar to a fizzy drink, the ocean can hold dissolved gases. The global ocean absorbs about one quarter of the annually emitted CO2 by humans. Half of this uptake occurs in the ocean surrounding Antarctica, i.e. the Southern Ocean making it one of the most important marine sinks for anthropogenic CO2.

However, the amount of CO2 absorbed by the Southern Ocean changes over the years. In the 1980s and 1990s, the Southern Ocean carbon sink stalled, while in the 2000s, the sink regained its expected uptake strength. Researchers at MPI-M have investigated what happened since then.

The Southern Ocean is extremely harsh, cold, and very remote. Hence, ship measurements are rare in this region. Therefore, Keppler and Landschützer used a machine learning algorithm to fill data gaps in the measurements.

They found that the Southern Ocean carbon sink has weakened again since 2012, despite a continued increase in atmospheric CO2. The authors explain this by shifts in regional wind pattern resulting in enhanced regional upwelling of carbon rich deep water. Like a fizzy drink losing its bubbles, some carbon at the surface returned to the air. This loss meant that overall less carbon was absorbed in the Southern Ocean.

Original publication:

Keppler, L. and P. Landschützer (2019) Regional Wind Variability Modulates the Southern Ocean Carbon Sink. Scientific Reports, 9:7384, doi.org/10.1038/s41598-019-43826-y

Contact:

Lydia Keppler
Max Planck Institute for Meteorology
Phone: +49 (0) 40 41173 184
Email: lydia.keppler@we dont want spammpimet.mpg.de

Dr Peter Landschützer
Max Planck Institute for Meteorology
Phone: +49 (0) 40 41173 145
Email: peter.landschuetzer@we dont want spammpimet.mpg.de