A recent study has revealed that more than one-fifth of the world’s oceans have darkened between 2003 and 2022, raising concerns about the health of marine ecosystems.

The phenomenon, known as “ocean darkening,” is driven by climate change, runoff, and shifts in marine biology, and could have long-term effects on oceanic life and the planet’s climate.

Key Points:

• Over 21% of the global ocean has darkened over the past two decades, affecting around 75 million square kilometers of marine area.
• In some regions, the sunlit "photic zone" of the ocean has shrunk by 50 to over 100 meters, reducing the depth to which sunlight can penetrate.
• Contributing factors include coastal runoff, changes in plankton communities, altered ocean circulation, and rising sea surface temperatures.
• Ocean darkening threatens marine species dependent on light for feeding, reproduction, and navigation, forcing them into shallower, more competitive zones.
• Scientists warn that this trend could disrupt marine food chains, affect global oxygen and carbon cycles, and challenge future climate and biodiversity stability.