Massive Volcanic Eruptions May Have Kickstarted Life as We Know It!

For billions of years, Earth’s atmosphere lacked the oxygen necessary to sustain complex life. While scientists have long credited photosynthetic microorganisms for the planet’s eventual oxygenation, new research suggests that volcanic activity may have played a critical role in triggering this transformation.

A study led by researchers from the University of Tokyo proposes that massive volcanic eruptions created brief spikes in atmospheric oxygen, setting the stage for the Great Oxygenation Event (GOE).

The Shifting Composition Of Earth’s Atmosphere

Today, Earth’s atmosphere is composed of approximately 21% oxygen, but this has not always been the case. More than 2.5 billion years ago, oxygen was nearly absent, and Earth’s air was dominated by carbon dioxide and other gases.

The prevailing theory suggests that early cyanobacteria, capable of photosynthesis, slowly transformed the planet’s atmosphere by producing oxygen over millions of years.

However, researchers now believe that prior to the GOE, the planet experienced short-lived bursts of oxygenation—referred to as “whiffs”—that were likely caused by volcanic activity.

How Volcanoes May Have Fueled Early Oxygenation?

These eruptions released large amounts of carbon dioxide, triggering a greenhouse effect that warmed the climate. This warming increased the weathering of rocks, releasing essential nutrients like phosphate into the oceans.

According to Professor Eiichi Tajika, one of the study’s authors, the presence of photosynthetic microorganisms alone would not have immediately led to atmospheric oxygenation because nutrient availability in the oceans was limited. “Activity of microorganisms in the ocean played a central role in the evolution of atmospheric oxygen,” he explains.

He further elaborates on the role of volcanism in early oxygenation: “It likely took some massive geological events to seed the oceans with nutrients, including the growth of the continents and, as we suggest in our paper, intense volcanic activity, which we know to have occurred.”

Evidence From Geological Records

To support their theory, the researchers examined redox-sensitive elements such as molybdenum, rhenium, and selenium. One well-documented oxygen spike occurred around 2.5 billion years ago and is preserved in geological formations such as the Mt. McRae Shale in Australia.

Lead author Yasuto Watanabe describes the challenges of modeling these ancient events. “The biggest challenge was to develop a numerical model that could simulate the complex, dynamic behavior of biogeochemical cycles under late Archean conditions,”he states.

Why These Short Oxygen Bursts Mattered?

These temporary spikes in atmospheric oxygen, though short-lived, may have played a crucial role in shaping the conditions necessary for the GOE. The researchers suggest that as volcanic activity continued over millions of years, these bursts helped push Earth’s atmosphere toward a tipping point, leading to a permanent shift in oxygen levels.

Watanabe highlights the importance of these transient oxygenation events:

“Understanding the whiffs is critical for constraining the timing of the emergence of photosynthetic microorganisms. The occurrences are inferred from concentrations of elements sensitive to atmospheric oxygen levels in the geologic record,”

This process likely contributed to the development of oxygen-utilizing enzymes in microorganisms, enabling life to gradually adapt to an oxygen-rich environment.