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Earth has a stabilizing mechanism that keeps it habitable

For the last 3.7 billion years, Earth’s climate has undergone drastic changes, and yet life has kept on beating. A new study from the Massachusetts Institute of Technology has confirmed that the Earth has a “stabilizing feedback” mechanism that has pulled the climate back from the brink, keeping global temperatures within a steady, habitable range.

According to the experts, this phenomenon is likely caused by “silicate weathering” – the slow and steady weathering of silicate rocks involving chemical reactions that draw carbon dioxide out of the atmosphere and into ocean sediments. The Earth’s enduring habitability points to some inherent, geologic check on extreme temperature swings.

“You have a planet whose climate was subjected to so many dramatic external changes. Why did life survive all this time? One argument is that we need some sort of stabilizing mechanism to keep temperatures suitable for life,” said study co-author Constantin Arnscheidt. “But it’s never been demonstrated from data that such a mechanism has consistently controlled Earth’s climate.”

Arnscheidt and Professor Daniel Rothman sought to confirm whether a stabilizing feedback has been at work by looking at data of global temperature fluctuations through geologic history. They worked with a range of global temperature records, from the chemical composition of ancient marine fossils and shells, as well as preserved Antarctic ice cores.

The team analyzed the history of average global temperatures over the last 66 million years, considering the entire period over different timescales to see whether any patterns of stabilizing feedback emerged.

Without stabilizing feedbacks, fluctuations of global temperature should grow with timescale. The study revealed a regime in which fluctuations did not grow, implying that a stabilizing mechanism reigned in the climate before fluctuations grew too extreme. 

The timescale for this stabilizing effect — hundreds of thousands of years — coincides with what scientists predict for silicate weathering.

On longer timescales, the data did not reveal any stabilizing feedbacks. Over these longer timescales, then, what has kept global temperatures in check?

“There’s an idea that chance may have played a major role in determining why, after more than 3 billion years, life still exists,” said Professor Rothman.

As the Earth’s temperatures change, these fluctuations may just happen to be within a range that a stabilizing feedback, such as silicate weathering, could periodically keep the climate in check – and within a habitable zone.

“There are two camps: Some say random chance is a good enough explanation, and others say there must be a stabilizing feedback,” said Arnscheidt. “We’re able to show, directly from data, that the answer is probably somewhere in between. In other words, there was some stabilization, but pure luck likely also played a role in keeping Earth continuously habitable.”

The results of the study, published in the journal Science Advances, imply that today’s global warming could be eventually canceled out by the stabilizing feedback. However, this would take hundreds of thousands of years to happen, and can’t be relied on to solve the climate crisis.

By Katherine Bucko, Staff Writer

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