The Role of the Southern Ocean in Global Climate Regulation

The Southern Ocean plays a crucial role in regulating the global climate due to its significant capacity to absorb carbon dioxide. It alone absorbs about 40% of the total carbon dioxide produced by human activities. This massive absorption makes it one of the most important natural defenses against global warming. But how does this complex system work? And what challenges does it face amid climate changes?

The Carbon Cycle in the Southern Ocean

Oceans act as vast carbon sinks due to the water cycle that transports deep, carbon-laden waters to the surface. This cycle involves gas exchange between the water and the atmosphere, before the waters sink back into the depths carrying the absorbed carbon. This balance depends on the amount of natural carbon dioxide that returns to the surface from ancient deep waters.

However, when carbon-rich waters reach the surface, they limit the ocean’s ability to absorb more industrial carbon dioxide. This process is significantly affected by different water layers and the strength of ocean currents.

Winds and Deep Water Variability

Climate models predict that the westerly winds will strengthen, bringing more carbon-rich deep waters to the surface. This change, driven by climate change, could reduce the ocean’s ability to absorb carbon dioxide in the long term.

Despite these challenges, recent data shows that the Southern Ocean remains a strong carbon sink. New research explains how changes in water layers have kept deep carbon trapped.

The Invisible Barrier

Deep waters in the Southern Ocean are usually found below 200 meters and are salty, nutrient-rich, and relatively warm. These waters contain large amounts of dissolved carbon dioxide that entered the ocean long ago. In contrast, waters near the surface are cooler, less salty, and carry less carbon dioxide.

As long as these layers remain strong, carbon dioxide stays trapped in the depths. However, if the boundaries between the layers weaken, the trapped carbon could rise to the surface and escape into the atmosphere.

Recent Changes and Their Impact

Recent research shows that strong westerly winds may push deep waters closer to the surface. Since the 1990s, the upper boundary of the deep water layer has risen by about 40 meters. These changes increase the risk of water mixing, which could lead to carbon dioxide leaking into the atmosphere.

Researcher Lea Olivier noted that the fresher surface water has temporarily compensated for the Southern Ocean’s weakened carbon absorption capacity. However, this situation may change if the layers weaken.

Conclusion

Studies indicate that the Southern Ocean remains a strong carbon sink despite climate changes. But as westerly winds continue to strengthen, we may see changes in the ocean’s natural balances, potentially weakening its role in carbon absorption. To better understand these processes and their impact on the climate, more research is needed, especially during winter months. These future studies will be crucial for understanding the impact of climate change on the oceans.