Earth (Representative Image: Canva)

In a recent study, scientists have unearthed intriguing evidence suggesting that the Earth's rotation slowed dramatically twice in the last several hundred million years, playing a critical role in some of the planet's most significant events. This groundbreaking research, led by Chinese scientists, links these shifts in rotational speed to both the largest mass extinction and the rapid expansion of life known as the Cambrian explosion.

Why Did the Earth's Rotation Slow Down?

The Earth’s rotation is influenced by gravitational interactions with the moon, which affect ocean tides. The friction between the Earth’s surface and these tides causes a gradual deceleration in rotation. Additionally, as Earth transfers momentum to the moon, the moon slowly moves away from the Earth. Over millions of years, these changes have contributed to a noticeable slowdown in Earth's rotation.

The Impact of Rotational Deceleration

Ma Chao, from the Institute of Sedimentary Geology at Chengdu University of Technology, and his team conducted a two-year analysis, revealing that between 700 million and 200 million years ago, the distance between the Earth and the moon increased by 20,000 kilometres. This shift led to an extension of the day by approximately 2.2 hours.

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The study identifies two significant periods of rotational deceleration: the first between 650 and 500 million years ago, coinciding with the Cambrian explosion, and the second between 350 and 280 million years ago, during the Permian-Triassic extinction event, also known as the "Great Dying," which wiped out 90% of life on Earth.

The Role of Volcanic Activity and Climate Change

The research suggests that the changes in Earth's rotation were linked to shifts in sea conditions, climate, and volcanic activity. These factors may have created the conditions necessary for the early evolution of marine ecosystems and, later, contributed to the catastrophic events leading to mass extinction. According to Ma, these “fast-slow” deceleration periods were crucial in shaping the history of life on Earth.

This study offers a new perspective on the dynamic relationship between Earth's rotational speed and the evolutionary and extinction events that have shaped the planet's history. As the research continues, scientists hope to further unravel the complex interactions that govern our planet's past and future.

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