Tiny Ocean Organisms Hold Key to Earth's Carbon Future

Strategic Insights -

Tiny ocean organisms, including calcifying plankton, have been found to play a crucial role in regulating the Earth's thermostat by capturing and cycling carbon. However, these organisms are oversimplified in climate models used to predict the planet's future, which may lead to an underestimation of key processes in the global carbon cycle and the ocean's capacity to respond to climate change. A new review published in Science highlights the unique traits of different calcifying plankton groups, which determine their geographic distribution, ecological role, and vulnerabilities.

Key Takeaways:

  • Calcifying plankton, including coccolithophores, foraminifers, and pteropods, are crucial for regulating the Earth's climate and influencing seawater chemistry, as they build minute shells of calcium carbonate (CaCO3) and facilitate the transfer of carbon from the atmosphere to the deep ocean.
  • The "carbon pump" created by these organisms helps regulate Earth's climate and influences everything from ocean chemistry to the fossil record.
  • Calcifying plankton build minute shells, but a large fraction of the calcium carbonate produced never reaches the seabed, dissolving instead in the upper ocean through biological interactions.
  • Shallow dissolution profoundly alters the ocean's chemistry but remains largely absent from key Earth System Models (e.g., CMIP6) that inform global climate assessments.
  • The study highlights the sensitivity of different calcifying plankton groups to climate stressors, with coccolithophores being especially sensitive to acidification.
  • Integrating calcifying plankton into climate models could offer sharper predictions and deeper insights into how ecosystems and societies may be affected.

Statistics:

  • The "carbon pump" created by calcifying plankton helps regulate Earth's climate and influences everything from ocean chemistry to the fossil record.
  • Up to 70% of the calcium carbonate produced by calcifying plankton dissolves in the upper ocean, altering the ocean's chemistry.
  • Coccolithophores, the main producers of CaCO3, are especially sensitive to acidification, with no specialized pumps to remove acidity from their cells.
  • Foraminifers and pteropods face different pressures, including oxygen loss and warming waters.
  • Global climate assessments may underestimate key processes in the global carbon cycle and the ocean's capacity to respond to climate change due to the oversimplification of calcifying plankton in climate models.

Sources:

  • Ziveri P, et al. (2025). Calcifying plankton: from biomineralization to global change. Science. DOI: 10.1126/science.adq8520.