Is the color of the ocean changing hues? In the past two decades, over 56% of the world’s oceans have changed colors in a manner that is not explicable by natural variability, leading experts to blame the phenomenon on climate change, CNN reported last week. The color of oceans and other waterways stems from the materials in their upper layers; a deep blue sea signifies little marine life, whereas greener waters indicate the existence of ecosystems that are dependent on plant-like organisms that contain chlorophyll known as phytoplankton, the news outlet explains.

What does this mean? Tropical oceans, which have an abundance of the phytoplankton necessary for sustaining marine life, have become greener over the past 20 years, which reflects a change in the ecosystem, according to research by scientists from the National Oceanography Center in the UK and the Massachusetts Institute of Technology in the US. The study used NASA’s earth orbiting satellite Aqua to analyze data collected between 2002-2022 to weed out differences in sea colors that are indistinguishable to the human eye.

The implications are not yet clear: While the changing of ocean colors still does not clearly indicate how ecosystems are changing, the researchers predict some regions will likely experience a shortage in phytoplankton growth, others will experience an increase, but ultimately it is probable all parts of the ocean will see alterations in the variety of phytoplankton they host as a result of climate change. Changes in phytoplankton volumes — which are natural carbon sinks that store greenhouse gasses — will hinder the ocean’s ability to store CO2 and will likely cause an imbalance in “the natural organization of ecosystems,” study co-author Stephanie Dutkiewicz notes.

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