By the end of the century the world's oceans will be bluer and greener thanks to a warming climate, according to a new study.
At the heart of the phenomenon lie tiny microorganisms in the ocean called phytoplankton(浮游植物). Because of the way light reflects off the organisms, these phytoplankton create colorful patterns at the ocean surface. Ocean color varies from green to blue, depending on the type and concentration of phytoplankton. Climate change will fuel the growth of phytoplankton in some areas, while reducing it in other spots, leading to changes in the ocean's appearance.
Phytoplankton live at the ocean surface, where they pull carbon dioxide into the ocean while giving off oxygen. When these organisms die, they bury carbon in the deep ocean, an important process that helps to regulate(调控)the global climate. But phytoplankton are vulnerable to the ocean's warming trend. Warming changes key characteristics of the ocean and can affect phytoplankton growth, since they need not only sunlight and carbon dioxide to grow, but also nutrients.
Stephanie Dutkiewicz at MIT built a climate model that projects changes to the oceans throughout the century. In a world that warms up by 3℃, multiple changes to the color of the oceans would occur. The model predicts that currently blue areas with little phytoplankton could become even bluer. But in some waters, such as those of the Arctic, a warming will make conditions more suitable for phytoplankton, and these areas will turn greener. Just as importantly, the type of phytoplankton is changing. As the base of the food web, if certain kinds begin to disappear from the ocean, it will change the types of fish that will survive, which could affect the food chain.
Whatever color changes the ocean experiences in the coming future will probably be too gradual and unnoticeable, but they could mean significant changes. "It'll be a while before we can statistically show that the changes are happening," Dutkiewicz said, "but the change in the color of the ocean will be one of the early warning signals that we really have changed our planet."
