Japanese scientists have discovered that Earth's early oceans were not blue, as we see them today, but had a bright green hue.
Why Were They Green?
A high concentration of dissolved iron in the water absorbed blue light and reflected green.
The activity of cyanobacteria, which absorbed available light, further intensified this effect.
Cyanobacteria – The Architects of the Modern Atmosphere
These microorganisms not only gave the oceans their green color but also produced oxygen, leading to the Great Oxygenation Event around 2.4 billion years ago. This dramatically changed Earth's atmospheric composition and paved the way for the development of complex life.
Confirmation Through Martian and Exoplanetary Studies
Understanding these processes helps scientists search for life on other planets. The presence of dissolved iron and microbial activity could indicate the potential habitability of distant worlds.
Green Water – A Possible Sign of Life on Other Planets?
If we find an exoplanet with similar conditions, it may also be undergoing its own evolutionary journey—from green oceans to an oxygen-rich world capable of supporting life.
This glimpse into Earth's past is yet another reminder of how remarkable and dynamic our planet truly is!