Climate change is causing the ocean to change color

By analyzing satellite photos and data, researchers have detected that the ocean is becoming greener.

Climate change is causing the ocean to change color
View of the Ocean Explorer, a luxury cruise ship carrying 206 people that ran aground, in Alpefjord, Greenland, September 13, 2023. Danish Air Force/Arctic Command/Handout via REUTERS

The ocean is blue. ish. Although different ocean regions vary a bit in color, its surface’s generally deep blue shade comes from the way that its water absorbs different colors on the light spectrum. The water doesn’t absorb blues like it does with colors on the red part of the spectrum, leaving us with the blue color we see when we go to the beach or fly to other continents.

But, with climate change shifting the ecosystems and structures within Earth’s oceans, could they start looking different, too? According to a recent study from the UK National Oceanography Center – yes. This study published in Nature shows that from 2002 to 2022, 56% of global ocean surface has changed in color. By analyzing satellite photos and data, researchers have detected that it’s becoming greener.

MIT, which also helped run the study, says, "The shift in ocean color indicates that ecosystems within the surface ocean must also be changing, as the color of the ocean is a literal reflection of the organisms and materials in its waters.”

Scientists are suggesting that this phenomenon has something to do with the way nutrients are distributed in the water. With rising ocean temperatures comes less mixing between the layers of water, so nutrients can’t move through the sea in the same way as before. Because of this, it’s possible that plankton is spreading in funky ways closer to the ocean’s surface in many areas.

Different species of plankton reflect light in diverse ways. Study co-author Stephanie Dutkiewicz explains: “...changes in color reflect changes in plankton communities, that will impact everything that feeds on plankton. It will also change how much the ocean will take up carbon, because different types of plankton have different abilities to do that. So, we hope people take this seriously. It’s not only models that are predicting these changes will happen. We can now see it happening, and the ocean is changing.”