Researchers have found that more than half of the oceans have changed color over the past 20 years, subtly changing from blue to green in some regions, highlighting the impact of climate change on life in the world’s oceans.
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According to a study published Wednesday in Nature, the change is due to a variation in ecosystems and specifically in plankton, which are at the heart of the marine food system and play a crucial role in the global carbon cycle and oil production. oxygen we breathe.
“The reason we’re interested in color changes is because color reflects the state of the ecosystem,” lead study author BB Cael of the National Oceanographic Center of Grande told AFP. -Brittany.
The color of the seas as seen from space can indeed give an idea of what is happening in the upper layers of the water: a deep blue means there is little life, while greener waters are likely to have more activity, particularly from phytoplankton, which, like plants, contains a green pigment bound to chlorophyll.
The evolution of phytoplankton and its concentration in certain regions to the detriment of others where it could disappear is far from trivial and could upset the entire marine food chain.
Scientists therefore want to develop ways to monitor these changes in ecosystems in order to track climate change and establish protected areas.
Expanding the color spectrum, the Nature study examined seven hues of the oceans monitored by the MODIS-Aqua satellite from 2002 to 2022. These hues are too subtle for humans to perceive and appear mostly blue to the naked eye.
The authors compared observational data with computer models of climate change. They concluded that the observed changes were broadly in line with the models’ predictions.
“I’ve been doing simulations for years that tell me these ocean color changes are going to happen. That this is actually happening isn’t surprising, it’s frightening,” said Stephanie Dutkiewicz, co-author of the study and a member of MIT’s Department of Earth, Atmospheric and Planetary Sciences.
While more work is needed to determine the exact effects of the color changes, the study’s authors think it’s highly likely that climate change is the cause.
“These changes are consistent with what is known about human-caused climate change,” Dutkiewicz said.