Much of the surface ocean will shift in color by end of 21st century: study

Source: MIT via Phys.org

Much of the surface ocean will shift in color by end of 21st century: study

February 4, 2019, Massachusetts Institute of Technology

Climate change is causing significant changes to phytoplankton in the world's oceans, and a new MIT study finds that over the coming decades these changes will affect the ocean's color, intensifying its blue regions and its green ones. Satellites should detect these changes in hue, providing early warning of wide-scale changes to marine ecosystems.

Writing in Nature Communications, researchers report that they have developed a global model that simulates the growth and interaction of different species of phytoplankton, or algae, and how the mix of species in various locations will change as temperatures rise around the world. The researchers also simulated the way phytoplankton absorb and reflect light, and how the ocean's color changes as global warming affects the makeup of phytoplankton communities.

The researchers ran the model through the end of the 21st century and found that, by the year 2100, more than 50 percent of the world's oceans will shift in color, due to climate change.

The study suggests that blue regions, such as the subtropics, will become even more blue, reflecting even less phytoplankton—and life in general—in those waters, compared with today. Some regions that are greener today, such as near the poles, may turn even deeper green, as warmer temperatures brew up larger blooms of more diverse phytoplankton.

"The model suggests the changes won't appear huge to the naked eye, and the ocean will still look like it has blue regions in the subtropics and greener regions near the equator and poles," says lead author Stephanie Dutkiewicz, a principal research scientist at MIT's Department of Earth, Atmospheric, and Planetary Sciences and the Joint Program on the Science and Policy of Global Change. "That basic pattern will still be there. But it'll be enough different that it will affect the rest of the food web that phytoplankton supports."

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Read more: https://phys.org/news/2019-02-surface-ocean-shift-21st-century.html

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Related: Ocean colour signature of climate change (Nature Communications)