Overview

• Satellite data from 2003 to 2022 reveal that 21% of the global ocean experienced a measurable decline in sunlight penetration.
• In the darkest regions, photic zones have become up to 50 meters shallower in 9% of areas and up to 100 meters shallower in 3% of areas.
• Darkening is most pronounced around the Gulf Stream and polar seas, while some mid-ocean zones have shown slight brightening.
• Contributing factors include coastal runoff and sedimentation, climate-driven shifts in phytoplankton and altered biological productivity.
• Researchers say reversing ocean darkening will require curbing land-based pollution, upgrading coastal infrastructure and intensifying climate mitigation.