Tiny Ocean Creatures Play Massive Role in Fighting Climate Change

Microscopic marine animals known as zooplankton are proving to be unsung heroes in the fight against climate change. New research reveals that these tiny organisms, which include copepods, krill, and salps, help remove millions of tonnes of carbon dioxide (CO₂) from the atmosphere each year through a natural process that has been significantly underestimated.

Every spring, zooplankton feed on blooms of phytoplankton—plant-like organisms that absorb CO₂ through photosynthesis—near the ocean's surface. The zooplankton convert this carbon into fat reserves, and then migrate to the deep ocean, diving hundreds of metres down. There, they metabolize the fat, effectively transporting the carbon far below the surface where it can remain sequestered for centuries. Scientists estimate that this process locks away around 65 million tonnes of carbon annually, roughly equivalent to the emissions produced by about 55 million cars.

This biological carbon pump is a critical part of Earth’s natural climate regulation. However, scientists are increasingly concerned that climate change could threaten the very species responsible for this service. Warmer ocean temperatures, changing currents, and disruptions to the marine food web could all impact zooplankton populations and their migratory behavior.

If the numbers of these tiny creatures decline, or if their deep dives become less frequent due to environmental shifts, the ocean’s capacity to store carbon may weaken. This could reduce one of nature’s most effective climate-mitigation systems, potentially accelerating the pace of global warming.

Experts say the findings highlight the need to better understand and protect ocean ecosystems, especially as human activity continues to alter the planet’s climate balance. Preserving the health of zooplankton and their role in the carbon cycle may be essential for long-term climate stability.