Climate Change Could Alter The Color Of The World’s Oceans By 2100, Study Warns

Caribbean sea surface summer wave background. Exotic water landscape with clouds on horizon.
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New research suggests that climate change could have an impact on the color of the water in our planet’s oceans, making it more intense over time as algae populations continue to fluctuate.

In a study published Monday in the journal Nature Communications, researchers from the Massachusetts Institute of Technology explained that ocean color could be one of the many features or characteristics of climate change. As phytoplankton, or algae, serves as the anchor of the marine food chain and also plays a key role in the carbon cycle, frequent changes in the population of algae could result in ocean waters becoming bluer in some parts and greener in others.

As summarized by Atlas Obscura, the above phenomenon is expected to take place because climate change has different effects on various species, phytoplankton included. Waters in the subtropics, for one, could turn a more intense shade of blue when populations of phytoplankton decrease. Meanwhile, waters near the poles could become greener over time due to global warming making it more conducive for algae to thrive in these waters.

Since algae contain chlorophyll — the same agent that absorbs sunlight during photosynthesis — this pigment absorbs the blue end of the light spectrum more than it does the green, thus making algae-filled waters greener. Conversely, water does not absorb blue light on its own, which makes it bluer as it gets emptier.

All in all, the researchers stressed, more than half of the world’s oceans will likely have some changes in color by the year 2100 due to the aforementioned waxing and waning of phytoplankton populations.

The above conclusion was based on the use of computer modeling that, per Atlas Obscura, “[built] upon earlier models” that have been used since the 1990s. These models drew information on the chlorophyll levels in water from the colors found in satellite images. However, the new methodologies improved on the old one because chlorophyll levels, on their own, are not guaranteed to provide insight on what’s happening with other organisms found in a typical marine ecosystem.

Given the aforementioned limitations, the new model introduced by the MIT researchers took a much wider range of variables into account, using color to analyze changes in how light is reflected and absorbed in the water. The researchers then noted how the colors of the world’s oceans changed in the model when temperatures were raised by three degrees Celsius, which is in line with predicted changes to water temperatures by the year 2100.

In a statement quoted by, lead author and MIT principal research scientist Stephanie Dutkiewicz explained that the color changes shown by the model might not appear significant to the naked eye, but could hint at something broader that might affect other creatures in the food web supported by the algae.

“Different types of phytoplankton absorb light differently, and if climate change shifts one community of phytoplankton to another, that will also change the types of food webs they can support,” said Dutkiewicz, who described the potential effect as being “quite serious.”