Earth’s Oceans Once Green, Study Reveals
Recent research by Japanese scientists has unveiled that Earth’s oceans were once predominantly green, a transformation linked to the evolution of photosynthesis. The study indicates that during a period spanning 1.5 billion years, the oceans were home to only single-celled organisms, while the surrounding landscapes were barren and rocky. This shift in ocean chemistry may explain the development of blue-green algae and their diverse photosynthetic pigments.
Before Blue: The Green Ocean Era
The report highlights a fascinating chapter in Earth’s history when its oceans were characterized by a green hue. This transformation is attributed to the chemistry and evolution of photosynthesis. Evidence from the Archean and Paleoproterozoic eras shows that banded iron formations, created between 3.8 and 1.8 billion years ago, were formed during a time when life was limited to single-celled organisms. The continents during this period were stark, consisting of gray, brown, and black rock and silt.
These banded iron formations serve as a geological record of the early Earth’s environment. They illustrate the oscillation between iron deposits that lacked oxygen and those that were oxidized, reflecting the changing conditions of the oceans. The study suggests that these changes in ocean chemistry played a crucial role in shaping the planet’s early ecosystems.
Green Seas Sparked Life
The emergence of life harnessing sunlight began in the Archean eon, a time when Earth’s atmosphere and oceans were devoid of gaseous oxygen. This early life initiated the “Great Oxidation Event,” a pivotal ecological shift that allowed for more complex organisms to thrive. These organisms utilized anaerobic photosynthesis, which is evident in the color variations of banded iron formations.
Research indicates that the greenish waters surrounding the Japanese volcanic island of Iwo Jima are linked to oxidized iron (Fe(III)). In these waters, blue-green algae flourish, suggesting that their ancestors evolved alongside other bacteria that utilized ferrous iron as an electron source for photosynthesis. This connection underscores the significance of ocean color in understanding the evolution of life on Earth.
Life Changes Ocean Colours
Photosynthetic organisms, primarily through pigments like chlorophyll, convert carbon dioxide into sugars using sunlight. Modern blue-green algae, genetically engineered to contain phycoerythrobilin (PEB), show enhanced growth in green waters. This finding implies that planets with pale-green oceans could be prime candidates for hosting early photosynthetic life.
The color of Earth’s oceans is intricately linked to water chemistry and biological influences. The study suggests that variations in ocean color could occur under different environmental conditions. For instance, purple oceans might emerge with high sulfur levels, while red oceans could result from intense tropical climates or algae associated with “red tides.” As the sun evolves, changes in ocean color are expected, highlighting the dynamic nature of Earth’s geological history.
Observer Voice is the one stop site for National, International news, Sports, Editor’s Choice, Art/culture contents, Quotes and much more. We also cover historical contents. Historical contents includes World History, Indian History, and what happened today. The website also covers Entertainment across the India and World.
