Researchers find that climate change is the likely cause behind the changing color of oceans.

A recent study has revealed that the oceans of today have undergone significant changes compared to those of 20 years ago. The study, published in the journal Nature, has found that around 56% of the world’s oceans have experienced a shift in color, with the once-blue waters turning greener over time. This change has been particularly noticeable in tropical ocean regions near the equator and is likely attributed to climate change.

Stephanie Dutkiewicz, a senior research scientist at MIT’s department of Earth, atmospheric and planetary sciences, and the Center for Global Change Science, commented on the findings, stating, “To actually witness this change is not surprising, but rather frightening. These alterations align with the changes induced by human activities impacting our climate.”

The color of the ocean is a result of what exists in its upper layers. Normally, the ocean appears blue because it acts as a filter for sunlight, with the water absorbing colors in the red part of the light spectrum, as explained by the National Oceanic and Atmospheric Administration. However, the presence of materials and life in the water can cause a greener color to emerge, which is largely influenced by the presence of phytoplankton.

Although most changes in color are too subtle for the human eye to detect, researchers utilized data from NASA’s Aqua satellite, which has been monitoring ocean color for the past 21 years. These findings led them to conclude that the change in color signifies the impact of climate change on surface marine microbial ecosystems.

Dutkiewicz further emphasized the significance of the color changes, stating that they reflect shifts in plankton communities, which will have a cascading effect on the entire food chain. In addition, the changes in plankton will also affect the ability of the ocean to absorb carbon dioxide. The researchers hope that this study will prompt people to take the situation seriously, as the observed changes are no longer just predictions but tangible evidence of an evolving ocean.

To determine the role of climate change, the research team simulated the appearance of the water with and without the addition of greenhouse gases. The results matched closely with the analysis of real-world satellite data, providing further support for the link between human-induced climate change and the observed color changes.

In the future, NASA plans to gather more data on ocean color through the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, scheduled to launch next year. The mission aims to provide global ocean color measurements, assisting scientists in understanding the exchange of carbon dioxide between the ocean and atmosphere.