Scientists said climate change is changing the color of the oceans from blue to green.

Researchers have found that over the past 20 years, more than half of the oceans have changed color, subtly shifting from blue to green in some areas, highlighting the impact of climate change on life in the world’s seas.

According to a study Posted Wednesday in natureThis change is due to variation in ecosystems, in particular plankton, which are the cornerstone of the marine food system and play a crucial role in the global carbon cycle and in the production of the oxygen we breathe.

“The reason we care about color changes is because color reflects the state of the ecosystem,” lead author of the study B.B. Kyle, of the National Oceanography Center in Grande, told AFP.

The color of the seas, seen from space, can give an idea of ​​what is going on in the upper layers of the water: a deep blue means that there is little life, while if the water is greener it is likely to be more active, especially from the phytoplankton it contains, Like plants, they contain a green pigment associated with chlorophyll.

Far from being trivial, the evolution of phytoplankton and their concentration in certain areas, at the expense of others in which they can disappear, can upset the entire marine food chain.

So scientists want to develop ways to monitor these changes in ecosystems in order to track climate change and establish protected areas.

Study the nature He expanded the range of colours, examining seven ocean hues monitored by the MODIS-Aqua satellite from 2002 to 2022. These hues are too subtle for humans to perceive and appear largely blue to the naked eye.

Its authors compared the observational data to computer models of climate change. They came to the conclusion that the observed changes closely matched what the models had predicted.

“I’ve been doing simulations for years telling me these ocean color changes are going to happen. Seeing this actually happen isn’t surprising, but scary,” said Stephanie Dutkiewicz, co-author of the study and 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 authors believe it is very likely that climate change is to blame.

“These changes are consistent with what is known about human-caused changes in climate,” Dutkiewicz said.

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