Author: BRADY DENNIS & CHRIS MOONEY / Source: ScienceAlert
By the end of the century, if not sooner, the world’s oceans will be bluer and greener thanks to a warming climate, scientists reported Monday.
And while the shift in color will be all but imperceptible to the human eye, it could hint at the profound changes in store for a wide array of marine life.
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.
Because of the way light reflects off the organisms, blooms of these phytoplankton create colorful patterns at the ocean’s surface.
Climate change will fuel the blooming of some phytoplankton in some areas, while reducing it in other spots, leading to subtle changes in the ocean’s appearance.
Ocean color varies from green to blue, depending on the type and concentration of phytoplankton, or algae, in any given area. A deep blue ocean typically means there is little phytoplankton present.
The more phytoplankton present, the more green the water appears. According to NASA, when sunlight hits the ocean, some of the light is reflected back directly, but most of it penetrates the ocean surface and interacts with the water molecules it encounters.
By keeping a close watch on ocean colors, scientists can better understand phytoplankton and how they impact the world around them.
“Color is going to be one of the early signals,” said Stephanie Dutkiewicz, a principal research scientist in MIT’s Center for Global Change Science and a co-author of Monday’s study in Nature Communications.
“We’re going to be able to see – not by eye but by instrument – that the color of the ocean is changed.”
Phytoplankton live at the ocean surface, where they use sunlight and carbon dioxide to engage in photosynthesis. They pull carbon into the ocean while giving off oxygen.
When these organisms die, they bury carbon in the deep ocean, a crucial process that helps to regulate the global climate.
But phytoplankton are vulnerable to the ocean’s current warming trend.
According to NASA, warming changes key properties of the ocean and can affect phytoplankton growth, since they…
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