Alarming study Deep currents in the Southern Ocean behave atypically - researchers warn
According to a recent study, the circulation in the Southern Ocean has changed differently than climate models expect. This could have consequences for the global climate.
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- An international team of researchers has discovered a previously unknown phenomenon with the help of earth observation satellites.
- The scientists were able to prove that the ocean circulation in the Southern Ocean is behaving atypically.
- This could have serious consequences for the global climate.
Global ocean circulation is crucial for the Earth's climate. The currents running through all the world's oceans transport heat from the surface to the depths. In other places, cold and nutrient-rich deep water returns to the surface.
Scientists have long observed that the northern motor of the global current system, AMOC (Atlantic Meridional Overturning Circulation) for short, is stuttering due to warming in the Arctic and inflowing meltwater.
Deep water releases CO₂
Scientists have now also detected a change in the Southern Ocean Circulation (SMOC). Using Earth observation satellites, a team of international researchers has recorded a deviation in ocean circulation in the Southern Hemisphere compared to the Kima models.
The study comes from the National Oceanographic Center (NOC) in the UK and was recently published in the scientific journal "PNAS". The scientists' measurements show that the Antarctic deep water, which is important for the Southern Meridional Overturning Circulation (SMOC), has become increasingly warmer in recent decades. Surface water is now being replaced by rising deep water, which is releasing heat and carbon dioxide (CO₂) that has been stored for centuries.
"We've never seen this before"
Antonio Turiel, a scientist at the Institute of Marine Research in Barcelona, explains: "We've never seen this before."
The upwelling of warm, CO₂-rich deep water is considered to be the cause of the accelerated melting of sea ice in the Southern Ocean.
This process could lead to a doubling of atmospheric CO₂ concentrations by releasing carbon that has been stored in the deep sea for centuries. The consequences for the global climate are not yet foreseeable. However, the effects would be dramatic, write the researchers involved in the study.
Consequences for the global climate unforeseeable
As early as 2023, scientist Qian Li from the Massachusetts Institute of Technology (MIT) warned: "The weakening of the Southern Circulation Pump would profoundly alter the marine circulation of heat, fresh water, oxygen, carbon and nutrients. The consequences of this would be felt throughout the global ocean for centuries to come."
The current NOC study points to alarming effects - also for the northern hemisphere. The overturning currents in the Southern Ocean play a key role in regulating the planet's heat and carbon. Their disruption could also have consequences for the North Atlantic overturning circulation - and thus for the climate in Europe and other regions.
Transparency note: An earlier version of this article referred to a reversal of the SMOC. The information was based on misleading passages in the underlying press release. The article was updated on July 7.
