Directly two new studies prove that plankton in the oceans is declining. The sole cause is the increasing warming of the oceans as a result of global warming caused by climate change.
This is proven, on the one hand, by the decline of the otherwise extensive fossil record of the plankton order Foraminifera, which leave behind tiny shells that fall to the seabed when they die. This biomass will decrease by 10% if the Earth warms by 3 degrees Celsius compared to pre-industrial levels.
In the other study, examining nearly two hundred thousand samples revealed that the abundance of Foraminifera has declined by almost a quarter since the 1940s, with many species migrating away from the equator and deeper into the water column to survive. Since plankton can only drift, but not swim deliberately in a specific direction, it is left to the chance of currents whether enough specimens successfully complete this migration to ensure the conservation of the species.
Plankton also has a carbon-sinking effect that counteracts global warming: when Foraminifera form their shells, they bind carbon with calcium to produce the building material for the shells. After they die, the shells fall to the seabed, keeping this carbon out of the atmosphere for a very long time.
Conversely, the increasing acidification of the oceans (carbon dioxide is also known as carbonic acid, meaning it dissolves calcium carbonate) already complicates shell formation in plankton, which, alongside warming, is a cause of the plankton decline.
Plankton is the foundation of the marine food chain - most fish species require plankton as their primary food source; nearly all of those fish that do not feed on plankton themselves feed on planktivores - without these tiny marine organisms, the system collapses from the bottom up as ultimately virtually all fish run out of food. It therefore concerns no less than all marine life.
Feedback loops with cascade effects, domino effects, and the butterfly effect - there are many exponential and chaotic consequences resulting from this.
It is time to actively take counter-measures.
Sources:
Ying, R., Monteiro, F.M., Wilson, J.D. et al. Past foraminiferal acclimatization capacity is limited during future warming. Nature (2024). https://doi.org/10.1038/s41586-024-08029-0
Chaabane, S., de Garidel-Thoron, T., Meilland, J. et al. Migrating is not enough for modern planktonic foraminifera in a changing ocean. Nature (2024). https://doi.org/10.1038/s41586-024-08191-5
