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A study by scientists from Nagoya University proves that the world's oceans had a green hue billions of years ago and may change their color again in the future.
In the early stages of Earth's existence, the oceans were much greener due to the presence of cyanobacteria, which dominated the aquatic environment. These microorganisms used pigments called "phycobilins" that absorbed red and green light, leaving the planet with a greenish color. In addition, the content of iron hydroxide in the water contributed to the absorption of blue light, which also enhanced the green hue of the ocean. Scientists note that changes in the spectrum of light available for photosynthesis influenced the evolution of early marine organisms.
The Voyager 1 image of Earth in 1990 earned the planet the nickname "Pale Blue Dot," but that wasn't always true. From 3 billion years ago to 600 million years ago, the oceans may have been more like a "pale green blob" than the blue world we see today.
But given the conditions of the early Earth, the atmosphere could have created a different visual effect, changing the color of the world's waters.
Modern research shows that the oceans may change their color again due to the effects of climate change. Rising temperatures contribute to the growth of phytoplankton populations, which is already noticeable in many regions of the world. According to the Massachusetts Institute of Technology, by the end of the century, half of the world's oceans will become greener. Analysis of changes in the color of water in 2023 showed that 56% of the ocean has already undergone these changes in the past two decades.
He also suggests that the ancient ocean may have been larger than the modern one, further influencing the overall appearance of the Earth. The results of these studies demonstrate that the color of our planet is not permanent and depends on natural processes.
If the warming trend continues, the oceans could return to green, although the reasons for this will be different from those that occurred billions of years ago. Today, the main factor is human activity, which is changing ecosystems and disrupting the balance of marine organisms. The color of the ocean is not only a visual indicator, but also a marker of global changes taking place in the planet's biosphere. The only constant characteristic of the Earth is its capacity for change.
