Every summer, the Southern Ocean near Antarctica becomes greener due to large blooms of phytoplankton. These tiny plants form the base of an important marine food web and help remove carbon dioxide from the air. Scientists have long explained these blooms by sunlight and ocean conditions. But new research shows earthquakes beneath the ocean floor also play a key role. The study titled “Southern Ocean net primary production influenced by seismically modulated hydrothermal iron” combined satellite data with seismic records. It looked at earthquakes of magnitude five or more before the summer growing season. The results showed that years with more earthquakes had bigger phytoplankton blooms. In quieter years, the blooms were smaller. This link comes from hydrothermal vents—natural openings on the seabed where hot water dissolves minerals like iron. Iron is scarce but vital for phytoplankton growth. Usually, iron stays deep underwater and rises slowly, but earthquakes shake the seabed and cause bursts of iron-rich fluid to move up faster. This can bring nutrients to the surface within weeks or months. When iron reaches surface waters, phytoplankton quickly grow and bloom across large areas. These blooms support zooplankton, fish, and other predators, boosting the whole food chain. At the same time, more phytoplankton means more carbon dioxide is absorbed via photosynthesis, helping the ocean fight climate change. The Southern Ocean is a huge part of our planet’s carbon cycle. Although earthquake-driven nutrient pulses happen irregularly, their effects can be powerful during active years. Traditional climate models don’t usually include earthquakes because they are unpredictable and brief. This new insight adds a fresh layer to how scientists understand ocean life and carbon cycling. Researchers note that similar effects may happen in other oceans with hydrothermal vents, but more data and better sensors are needed. For now, it is clear that deep Earth movements quietly shape the vibrant life blooming on the ocean’s surface each summer.