South Africa funds research into ocean acidification threatening fish stocks and coastal e

Seawater chemistry is changing in ways that threaten the foundation of marine life and the livelihoods that depend on it. As carbon dioxide dissolves into the ocean, the water becomes more acidic, reducing the carbonate ions that corals, shellfish, pteropods and microscopic plankton need to build shells and skeletons. These organisms form the base of marine ecosystems and fisheries that sustain food security and coastal economies across the globe. Understanding where and when ocean acidification will intensify has become essential for effective marine conservation and sustainable resource management.

That urgent question sits at the heart of South Africa’s recent participation in the WHIRLS expedition aboard the SA Agulhas II Research Vessel. The expedition focused on the Cape Basin and the Agulhas Bank, offering a window into the complexity of how the ocean absorbs, stores and releases carbon. For a nation surrounded by three oceans and home to one of the world’s most dynamic marine environments, this scientific work carries both opportunity and responsibility.

The ocean absorbs approximately a quarter of humanity’s carbon dioxide emissions, slowing the pace of global warming and buying time for societies to transition to a low-carbon future. Yet this natural service cannot be assumed to continue indefinitely. Scientists have long understood that the ocean is a vital carbon sink, but what is becoming increasingly clear is that the processes controlling this sink operate at remarkably fine scales. Small ocean eddies, fronts and mixing processes influence where carbon enters the ocean, how deeply it is transported and how long it remains stored before returning to the atmosphere. These processes ultimately affect global climate, marine ecosystems and the health of coastal waters.

During the expedition, researchers continuously measured seawater carbon dioxide, pH, dissolved inorganic carbon, total alkalinity and chlorophyll while collecting water samples from the surface to 1,200 meters depth. This combination of high-resolution observations allowed the team to examine carbon dynamics with unprecedented detail across contrasting ocean features.

The preliminary findings reveal why such detailed observations matter. Cyclonic eddies appear to bring carbon-rich deep water toward the surface, potentially increasing the release of carbon dioxide back into the atmosphere while simultaneously intensifying local ocean acidification. Anticyclonic eddies, by contrast, transport surface waters downward, helping redistribute carbon into deeper layers of the ocean. These dynamic processes demonstrate that the ocean is not a passive reservoir but a living, constantly changing system whose behavior influences climate at regional and global scales.

South Africa occupies a strategically important position in the global ocean circulation system. The interaction between the Agulhas Current, the Southern Ocean and the South Atlantic influences weather patterns, biodiversity and carbon exchange far beyond the nation’s coastline. Scientific observations collected in South African waters contribute not only to national environmental management but also to international efforts to improve climate models and predict future climate change. Sustained investment in ocean observation is therefore not a luxury reserved for scientists. It is an investment in better climate forecasting, stronger environmental policy, resilient coastal economies and evidence-based decision making.

Reliable data enables governments to develop effective adaptation strategies, supports responsible fisheries management and strengthens South Africa’s contribution to international climate science. The WHIRLS expedition also demonstrated another equally important reality: scientific progress depends on people. Behind every dataset are researchers working long hours under demanding conditions, maintaining sophisticated instruments, ensuring analytical precision and mentoring the next generation of scientists. The collaboration between South African institutions and international partners illustrated how shared expertise can advance knowledge while building national scientific capacity.

As climate change accelerates, society will increasingly rely on science to navigate uncertainty. Science can only inform policy, however, if it is supported by sustained observations, modern infrastructure and skilled researchers capable of interpreting increasingly complex environmental changes. South Africa has already demonstrated that it possesses both the expertise and the institutional capability to contribute meaningfully to global ocean science. The challenge now is to ensure that this capability continues to grow. Long-term investment in marine research, observational programmes and scientific training will yield dividends far beyond academia. It will strengthen climate resilience, support the blue economy and safeguard the marine ecosystems upon which future generations depend.

The ocean has quietly protected humanity for decades by absorbing much of the carbon we have emitted. Understanding how long it can continue to do so, and under what conditions, may prove to be one of the most consequential scientific questions of this century. Whether South Africa’s current institutional momentum translates into the sustained, long-term funding that kind of question demands remains to be seen.