New research published in Science Advances finds the Southern Ocean is emitting about 40% more CO2 than earlier estimates, based on expanded active remote-sensing observations that reduce winter and regional sampling gaps. The region remains the largest source of uncertainty in global CO2 fluxes, and the revised outgassing could alter the global carbon budget and influence IPCC climate models. Rising atmospheric CO2—now increasing much faster than past natural rates—heightens concerns about warming, ocean acidification, and more volatile seas.
Southern Ocean Is Releasing About 40% More CO2 Than Previously Estimated — New Sensors Shift the Global Carbon Picture
New research published in Science Advances finds the Southern Ocean is emitting about 40% more CO2 than earlier estimates, based on expanded active remote-sensing observations that reduce winter and regional sampling gaps. The region remains the largest source of uncertainty in global CO2 fluxes, and the revised outgassing could alter the global carbon budget and influence IPCC climate models. Rising atmospheric CO2—now increasing much faster than past natural rates—heightens concerns about warming, ocean acidification, and more volatile seas.
06:04 AM, 11/19/2025Environment
New observational data indicate the Southern Ocean is outgassing roughly 40% more carbon dioxide (CO2) than earlier estimates, according to a study by the Second Institute of Oceanography, Ministry of Natural Resources (SIO-MNR) and the Nanjing Institute of Oceanography published in Science Advances. Improved measurements come from active remote-sensing methods that fill persistent observation gaps in the region’s harsh conditions.
How the findings were made
Researchers used active remote-sensing platforms to collect continuous data across areas and seasons that were previously under-sampled, especially during the dark, stormy Southern Hemisphere winter. This extended coverage reduced uncertainty in CO2 flux estimates and revealed stronger net outgassing than prior, more sparse observations suggested.
Regional drivers of CO2 exchange
CO2 exchange in the Southern Ocean varies by latitude:
- Antarctic Loop (south of 60°S): sea-ice dynamics and salinity primarily control gas exchange.
- Polar Front Loop (45°S–60°S): interactions between atmospheric CO2 and biological productivity (chlorophyll) are important.
- Subpolar Loop (north of 45°S): sea surface temperature becomes the dominant factor.
Why this matters
The Southern Ocean absorbs a significant portion of human-caused CO2 but has long been the single largest source of uncertainty in global CO2 flux estimates. Revising its outgassing upward could change calculations of the global carbon budget and affect the climate projections used by the Intergovernmental Panel on Climate Change (IPCC).
Broader context and implications
Atmospheric CO2 concentrations continue to climb: the National Oceanic and Atmospheric Administration (NOAA) notes that the annual rate of CO2 increase over the past 60 years is roughly 100 times faster than comparable natural rises at the end of the last ice age. Higher atmospheric CO2 tends to drive warmer temperatures and ocean acidification, with consequences for marine ecosystems, coastal communities and weather extremes.
For coastal recreation and surf communities, this may mean more variable and sometimes rougher seas; any potential increase in swell is a small and uncertain consolation compared with the wider risks to ecosystems and infrastructure.
Sources: Study in Science Advances; Second Institute of Oceanography (SIO-MNR); Nanjing Institute of Oceanography; NOAA climate data.