Yellow, purple? Not exactly.... Nevertheless, our oceans should change colour. This is the result of a study by MIT, the University of California and the University of Southampton. Before the end of the 21st century, the oceans are expected to have much more pronounced contrasts of blue and green. This is due to the phytoplankton that will no longer be able to feed properly. Indeed, phytoplankton are extremely sensitive to ocean temperature variations. Changes in their distribution across the world's waters have been observed, particularly due to warming in Arctic regions.

Thus, in regions where this plant plankton is very present, the water will be particularly green (the polar regions). On the other hand, where it is almost absent, the water will be more blue (subtropical regions). 

In addition to colouring the oceans, phytoplankton are mainly responsible for transforming Co2 into organic matter (food for many marine animals). But due to the warming of the oceans, phytoplankton are finding it increasingly difficult to do this task. This makes the water much more acidic, resulting in the death of many limestone plant and animal species (such as corals, for example).

In addition, warmer surface water reduces the availability of nutrients necessary for the survival of this organism. 

As we have seen, phytoplankton move on the surface of the planet as a function of water temperature. This will have the effect, by 2100, of changing the colour of our oceans in particular. "There will be a significant difference in the colour of 50% of the ocean by the end of the 21st century," explains Stéphanie Dutkiewicz, a biogeochemistry researcher (expert on the influence of physics and chemistry on phytoplankton biogeography), in a statement.

Turning from blue to green is not an incredible change for us, but significant and serious for the ocean.