Earth May Lose Its Blue Colour by 2100: MIT Study

Gwen Vasquez
February 5, 2019

It all comes down to a tiny organism called phytoplankton, or algae, which contains chlorophyll and lives in the ocean. The study added that due to climate change the colour of ocean surface will change by end of 21st century and it will alter the look of earth.

According to MIT study, the blue regions, such as the subtropics, will turn shades darker, which will reflect even less phytoplankton in those waters.

At the heart of the phenomenon lie tiny marine microorganisms called phytoplankton, which are crucial to ocean food webs and to the global cycling of carbon - and sensitive to the temperature of ocean waters.

Dutkiewicz's co-authors include Oliver Jahn of MIT, Anna Hickman of the University of Southhampton, Stephanie Henson of the National Oceanography Centre Southampton, Claudie Beaulieu of the University of California at Santa Cruz, and Erwan Monier, former principal research scientist at the MIT Center for Global Change Science, and now assistant professor at the University of California at Davis, in the Department of Land, Air and Water Resources. They're able to do this because water absorbs most sunlight with the exception of blue parts of the spectrum, which is reflected back out. Patches of ocean with a lot of algae appear greenish, for instance, while areas with fewer phytoplankton appear a deeper blue. That's why relatively-pure oceans or other bodies of water look blue from space. The more phytoplankton present, the more green the water appears.

Since the late 1990s, satellites have taken continuous measurements of the ocean's colour.

An example of how phytoplankton can change ocean color.

The team, which includes researchers from MIT, University of Southhampton, National Oceanography Centre Southampton, University of California at Santa Cruz, and University of California at Davis, states that the new model shows that the effects of climate change on the oceans is far more rapid than expected.

"An El Niño or La Niña event will throw up a very large change in chlorophyll because it's changing the amount of nutrients that are coming into the system", Dutkiewicz said.

They serve as food to many aquatic animals but can also become risky. This model takes information about phytoplankton, such as feeding and growth patterns, and incorporates it into a physical model that simulates the ocean's currents and mixing. Researchers also studied satellite images to better understand how different types of phytoplankton species absorb and reflect light.

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Scientists say there will be less of them in the waters in the decades to come.

"Other things will absorb or scatter it, like something with a hard shell". That gets reflected back out, giving it its deep blue color.

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When they increased the global temperatures by up to 3 degrees Celsius by 2100, they found that wavelengths of light in the blue or green wave band responded the fastest.

They believe it will be 30-40 years before they can say for certain that climate change is having an impact on chlorophyll. "But you can see a significant, climate-related shift in some of these wavebands, in the signal being sent out to the satellites".

Hickman said this was helpful, as using satellite data to examine specific changes in blue/green light can reveal changes in the phytoplankton population.

Writing in the journal Nature Communications, scientists from the Massachusetts Institute of Technology said that this would provide an early warning of wider changes to ocean ecosystems caused by climate change. "By the end of the century, our blue planet may look visibly altered", wrote Jennifer Chu in the press release.

MIT scientist who led the study says there will be a notable difference in the colour of 50% of the oceans by 2100, and it could be "quite serious". Since much of the ocean's color comes from phytoplankton, Dutkiewicz and her team suspected that if these communities change, then the color of the ocean is likely to vary along with them.

This research was supported, in part, by NASA and the Department of Energy.

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