Earth’s Oceans Are Turning Greener Due to Climate Change - Scientists Say It’s Not a Good Sign

A typical view of oceans is that they are leviathan beasts welling with sparkling turquoise waters. During the course of a day, these waters shift colors many times. When the chemicals in a jellyfish’s body give off a surreal glow or when a peacock mantis shrimp radiates a palette of greens, blues, pinks, and yellows, or when a purple sail adds a purplish tint, the waters dance with color. But these are occasional shifts. But in an astounding study published in the journal Nature, scientists have revealed that more than half the world’s ocean area is “becoming greener,” and the change is connected to human-caused climate change. 

The researchers estimated that these color changes could become apparent to the naked eye within 20 years. "I've been running simulations that have been telling me for years that these changes in ocean color are going to happen," Stephanie Dutkiewicz, the study's co-author and senior research scientist from Massachusetts Institute of Technology said in a statement. "To actually see it happening for real is not surprising, but frightening. And these changes are consistent with man-induced changes to our climate."

Currently, this color change is not visible to the naked eye, as lead author, B B Cael, told BBC. "The color itself is not something that's easy to describe with human language or that you can even see that well," however, she added that creatures like mantis shrimp or butterflies could easily spot this change. The researchers analyzed over 20 years of satellite data to deduce that nearly 56 percent of the world’s oceans are shifting in color, particularly turning greener. The change was most apparent in lower latitudes including subtropics and tropics.

After analyzing the satellite imagery, the team then employed a computer model to determine whether climate change could be a cause of this color change. They created a set of simulations to represent oceans under climate change and another set to represent oceans with no climate change. They compared both simulations. The model suggested that indeed the global rising temperatures are to blame for the changing hues.

Typically, the color of oceans comes from tiny organisms called “phytoplanktons.” Phytoplanktons are microscopic plant-like creatures that influence the entire network of the marine food chain and also play a key role in trapping carbon dioxide. "Different phytoplankton have different combinations of pigments used to photosynthesize. These pigments absorb light at different wavelengths," Cael explained to BBC. Scientists believe that this color change is driven by shifting concentrations of phytoplanktons in the oceans, largely caused by exacerbating climate crises triggered by humans.

“This evidence shows how human activities are affecting life on Earth on a vast scale,” Cael told Earth.com. “It’s another way humans are impacting the biosphere, affecting even the most extensive environments on the planet.” She added that it isn’t just about the aesthetics but about the balance of the entire marine ecosystem. "It's not really the color itself that we care about," she told BBC. "What matters is the change in color reflects the change in the ecosystem. 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," cautioned Dutkiewicz.