May 27, 2025 06:24 PM
https://www.eurekalert.org/news-releases/1085194
INTRO: More than one-fifth of the global ocean – an area spanning more than 75million 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 modelling to analyse 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.
In addition to this, more than 9% of the ocean – an area of more than 32million sq km, similar in size to the continent of Africa – had seen photic zone depths reducing by more than 50metres, while 2.6% saw the photic zone reduced by more than 100m. However, the picture is not solely of a darkening ocean with around 10% of the ocean – more than 37million sq km – becoming lighter over the past 20 years.
While the precise implications of the changes are not wholly clear, the researchers say it could affect huge numbers of the planet’s marine species and the ecosystem services provided by the ocean as a whole... (MORE - details, no ads)
INTRO: More than one-fifth of the global ocean – an area spanning more than 75million 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 modelling to analyse 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.
In addition to this, more than 9% of the ocean – an area of more than 32million sq km, similar in size to the continent of Africa – had seen photic zone depths reducing by more than 50metres, while 2.6% saw the photic zone reduced by more than 100m. However, the picture is not solely of a darkening ocean with around 10% of the ocean – more than 37million sq km – becoming lighter over the past 20 years.
While the precise implications of the changes are not wholly clear, the researchers say it could affect huge numbers of the planet’s marine species and the ecosystem services provided by the ocean as a whole... (MORE - details, no ads)