Two decades of satellite images have revealed that more than 56% of the world's oceans have seen significant changes in color. Scientists fear these color changes could be harbingers of yet another global crisis in ocean food chains as the planet warms. Greener oceans mean more life — and that's not necessarily goodThe color of the oceans can tell us a lot about their health. The ocean's color depends on what's in the upper layer of the water column. In the latest study, scientists used imagery from NASA's Aqua satellite, which has been monitoring ocean color changes for more than two decades.

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Persons: It's, it's, Cael, that's, Stephanie Dutkiewicz, Dutkiewicz, I've, Michael J Behrenfeld Organizations: Service, Nature, National Oceanography Center, Guardian, MIT's Department of, Planetary Sciences, Center for Global Change Science, CNN, Oregon State University Locations: Southampton