How ancient Scottish rocks throw ‘snowball Earth’ theory up in the air | Geology
During the “Snowball Earth” period, about 700 million years ago, Earth’s climate came to a standstill. The planet was encased in ice and isolated from seasonal variations: spring, summer, fall and winter all stopped. Or at least that was the theory.
A recent examination of some ancient rocks from the west coast of Scotland has now overturned this idea, suggesting that there were periods during Snowball Earth when the climate woke up.
Thomas Gernon and Chloe Griffin of the University of Southampton, along with other colleagues, studied rocks from the isolated islands of the Garvellachs that were deposited during Earth’s snowball period.
Under a microscope, they were able to examine 2,600 extremely preserved layers, recording climate changes year after year. Variations in layer thickness revealed climate cycles similar to those seen today, such as solar cycles and El Niño oscillations.
Their findings, published in Earth and Planetary Science Letters, suggest that such events were rare during Earth’s snowball and that these particular rocks recorded a muddy interlude lasting a few thousand years, when a small fraction of the ocean thawed and the climate briefly woke up.
But these discoveries are much more than just a curiosity. They shed light on the true sensitivity of the Earth’s climate system and offer important insights into how Earth might respond to major disturbances in the future.
