The ocean’s color has changed over the last 20 years, and the global trend is likely to be a consequence of human-caused climate change. This is one of a new study by scientists, including from Oregon State University.
In a study published in Nature, a team of researchers from the National Oceanography Center in England, MIT, and the University of Maine, note that they have detected changes in ocean color over the past two decades that cannot be explained by nature.
In particular, the researchers found that tropical ocean areas near the equator have become greener over time. This shift in the color of the oceans shows that the ecosystems on the surface of the oceans must also change, because the color of the oceans is a literal reflection of the materials and organisms in its waters.
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At this point, researchers can’t be sure exactly how the marine ecosystem changed to reflect the change in color. However, they are quite sure of one thing, namely, the most likely cause is climate change due to human activities.
The color of the ocean is a visual product of whatever is in its upper layers. Generally, waters that are dark blue indicate very little life, whereas waters that are greener indicate the presence of ecosystems, and especially phytoplankton.
The color differences captured by satellite are too subtle to be distinguished by the human eye. Most of the ocean will appear blue to our eyes, whereas its true colors may contain a finer mix of wavelengths, from blue to green and even red.
To see if these trends are related to climate change, Cael, an Oregon State oceanographer, looked at a model developed in 2019 by Stephanie Dutkiewicz of MIT. He found that Earth’s oceans were under two scenarios, one with the addition of greenhouse gases, and the other without the addition of greenhouse gases. The greenhouse gas model found that a significant trend will appear in 20 years, and almost cause a change in the color of the oceans around 50% of the world’s sea level. This, too, is almost exactly what Cael found in his analysis of real-world satellite data.
Source: Oregon State University
