Tiny plankton overlooked in climate forecasting may shape carbon cycles

Tiny plankton overlooked in climate forecasting may shape carbon cycles
by Hugo Ritmico
Barcelona, Spain (SPX) Oct 24, 2025

A newly published review in Science warns that tiny calcifying plankton-coccolithophores, foraminifers, and pteropods-play a greater role in Earth's carbon regulation than climate models currently account for. Researchers led by the Institute of Environmental Science and Technology at Universitat Autonoma de Barcelona reveal that these organisms are often oversimplified or omitted, leading to underestimations of the ocean's ability to cycle and store carbon.

These plankton construct calcium carbonate shells, enabling the transfer of atmospheric carbon to deep ocean reservoirs. By influencing ocean chemistry, they are an integral component of the global carbon pump that stabilizes planetary climate.

Patrizia Ziveri, ICREA research professor at ICTA-UAB and lead author, stated, "Plankton shells are tiny, but together they shape the chemistry of our oceans and the climate of our planet." Ziveri pointed out that failure to include them risks missing critical climate responses.

Much of the calcium carbonate produced does not reach the seafloor; instead, it dissolves in the upper layers through biological interactions-predation, aggregation, and respiration-and this so-called shallow dissolution significantly alters ocean chemistry. These processes, however, are largely absent from key Earth System Models like CMIP6.

The study emphasizes the need to account for the unique sensitivities of different plankton types: coccolithophores are vulnerable to acidification due to their lack of mechanisms for removing acidity, while foraminifers and pteropods are affected by warming and oxygen loss. Together, their diversity and functions dictate the ocean's response to climate change.

Researchers call for urgent improvements in measuring and modeling group-specific calcification, dissolution, and export to refine projections of climate, sediment record interpretations, and carbon sequestration estimates. Ziveri noted, "If we ignore the ocean's smallest organisms, we might miss important climate dynamics. Integrating calcifying plankton into climate models could offer sharper predictions and deeper insights into how ecosystems and societies may be affected."

The review concludes that tackling these gaps is essential to advance climate models that more accurately reflect oceanic biological complexities.

Research Report:Calcifying plankton: From biomineralization to global change