Our Oceans are Changing Colour


Illustration by Emilie Muszczak
Words by Iris Du

“I remember when the sea was blue.”

It’s a strange statement to think of anyone saying, let alone our children or grandchildren. However, our planet’s not-so-distant future is not far from this reality.

Researchers at MIT have recently developed a electronic model from satellite images and current meteorological reports which has revealed a bizarre, less-spoken about effect of our Earth heating up. They predict that by the end of the century, more than 50% of our oceans will have changed colour. We might see a future where The Big Blue becomes The Great Green.

There will be a noticeable difference in the colour of 50 percent of the ocean by the end of the 21st century… It could be potentially quite serious.
— Stephanie Dutkiewicz, MIT Research Scientist

Water molecules, like any other particle, absorb light. The dominant light wavelengths water absorbs are red, green and yellow, leaving the blue hue to reach our eyes. This results in large bodies of water appearing blue to the naked eye.  

As our planet gets warmer, ocean water close to the poles will heat up, causing populations of  a miniscule marine organism called phytoplankton to rise. Phytoplankton contains chlorophyll, the same pigment that gives leaves their colour. As phytoplankton thrive, the oceans will get greener.

Simultaneously, oceans close to the tropics — which already have slight green tones — are likely to get too warm for existing phytoplankton cultures to survive, causing the water to go from light turquoise to an intense, darker blue.

As strange and perhaps even alluring this environmental colour-change may seem, the idea of green oceans is a sign of deeper issues. The MIT model is the first to find a direct link between global warming and the levels of phytoplankton in our oceans. While previous research has been ambiguous, they can now deduce that global warming is playing a fundamental role in the state of our ocean’s future micro-cultures.

As strange and perhaps even alluring this environmental colour-change may seem, the idea of green oceans is a sign of deeper issues.

Green or dark oceans doesn’t just mean our future could be home to more phytoplankton. Like all populations, changes in one specie can have a chain reaction on all related food chains, both in water and on land, tipping the balance out of control.

Regardless of whether our future planet will be as technicoloured as researchers predict, these developments remind us that global warming-related repercussions not only appear in the form of unmissable natural disasters, but also at a microscopic level.

Keep Reading:

More on the MIT research study and the ocean model
NASA on the science behind ocean colour
National Geographic coverage on the subject