Thursday May 29, 2025
PhysOrg —
More than one-fifth of the global ocean—an area spanning more than 75 million sq km—has been the subject of ocean darkening over the past two decades, according to new research.
Ocean darkening occurs when changes in the optical properties of the ocean reduce the depth of its photic zones, home to 90% of all marine life and places where sunlight and moonlight drive ecological interactions.
For the new study, published in Global Change Biology, researchers used a combination of satellite data and numerical modeling to analyze annual changes in the depth of photic zones all over the planet.
They found that between 2003 and 2022, 21% of the global ocean—including large expanses of both coastal regions and the open ocean—had become darker.