It ain’t easy being green(er). Photo: Unsplash
According to a new study, our oceans have been changing color over the last few decades. The reason won’t surprise you: it’s climate change. The study, which was published on July 12 in the journal Nature, found that over half of the world’s oceans are going from a shade of blue to a greener hue.
“To actually see it happening for real is not surprising, but frightening,” said Stephanie Dutkiewicz, a coauthor of the study. “And these changes are consistent with man-induced changes to our climate.”
The color of the ocean is a direct result of what’s hanging around in the upper layers. When sunlight hits it, the ocean absorbs the light and filters out the reds in the spectrum. But when those upper layers are full of organic material like phytoplankton, that light bounces off them and produces the greener color. Although much of the color change in the last 20-or-so years is so subtle it’s tough to impossible for the human eye to perceive, it’s definitely happening. The study used data from the Moderate Resolution Imaging Spectroradiometer, which has been monitoring ocean color from NASA’s aptly named Aqua satellite for 21 years.
There are a variety of reasons for the uptick in phytoplankton in the oceans, but one of the most important is the warming waters. Plankton is a sort of foundational piece of all life on Earth, so big changes at that level will have broad and far-reaching effects.
“It will also change how much the ocean will take up carbon, because different types of plankton have different abilities to do that,” Dutkiewicz, said. “So we hope people take this seriously. It’s not only models that are predicting these changes will happen. We can now see it happening, and the ocean is changing.”
As scientists like to do, they’re going to continue monitoring the color of the ocean. Next year, NASA is launching the (again, aptly-named) Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, which will take global ocean color measurements to help scientists understand how the ocean and atmosphere exchange carbon dioxide.
