From Green to Blue: The Evolving Colors of Earth's Oceans

Japanese researchers suggest Earth's ancient oceans were once green due to high iron levels and anaerobic photosynthesis. This study, published in Nature, explores how changes in ocean chemistry and early photosynthetic life drove the transition to Earth’s current blue oceans, highlighting the dynamic nature of our planet's history.

A recent study by Japanese researchers posits a fascinating possibility: Earth's oceans were once green. The study, published in Nature, delves into the chemistry of ancient oceans and the evolution of photosynthetic organisms that led to the planet's current blue waters.

The premise is based on the presence of iron and the processes of anaerobic photosynthesis during the Archean eon, approximately 3.8 to 1.8 billion years ago. The researchers suggest high levels of dissolved iron in ancient oceans could have imparted a green hue, as seen today around volcanic islands like Iwo Jima.

The study also explores how early photosynthesis contributed to the 'great oxidation event,' allowing for an oxygen-rich atmosphere and blue oceans. Such findings paint a picture of Earth's oceans as ever-changing, with future shifts in color possible due to natural or astronomical phenomena.

(With inputs from agencies.)