A peer-reviewed model links colder oceans to more efficient transport of plankton carbon into deep water. Different temperature responses in photosynthesis and respiration could account for about a quarter of the ice-age atmospheric carbon dioxide decline. The estimate combines modern observations with reconstructed temperatures and remains sensitive to nutrient constraints and ocean chemistry.
Cooling may have helped plankton move more carbon from the ocean surface into deeper waters during the last glacial period. A peer-reviewed modelling study published on 29 October examines how photosynthetic organisms and organisms consuming their organic matter respond differently to temperature. The proposed mechanism connects the metabolism of small marine organisms with a portion of the atmospheric carbon dioxide decline during the ice age.[1], [2]
Phytoplankton make organic matter through photosynthesis. Consumers break that material down and release carbon into the surrounding water through respiration. In the model, cooling slows consumption more strongly, leaving a greater share of surface production available for export. Researchers compared the predicted temperature relationships with modern growth-rate measurements and independent carbon-export datasets before applying reconstructed glacial sea-surface temperatures.[1]
The calculations give an atmospheric reduction of about 20 ± 5 parts per million (ppm), against a total glacial difference of roughly 90 ppm. A separate ocean model estimates 18 ppm for this mechanism. The regional calculation excludes iron-limited southern waters. Reconstructed temperatures, productivity and carbon chemistry affect the estimate; circulation and nutrient supply remain other contributors to the wider carbon balance.[1]
