Earth is able to regulate and stabilize its temperature over enormous timescales—about 100,000 years on average—even after drastic climate changes caused by ice ages, changes in solar radiation, and intense volcanic activity, according to new research. The team behind the new study says this “stabilizing feedback” is part of Earth’s ability to sustain life for the past 3.7 billion years. This feedback was previously assumed, but now there is direct evidence.

To find this evidence, the researchers applied mathematical modeling to determine whether fluctuations in Earth’s average temperatures could be limited by one or more factors, by digging deep into available paleoclimate data collected over the past 66 million years.

“You have a planet whose climate has undergone many dramatic external changes,” says Constantin Arnscheidt, a climatologist at the Massachusetts Institute of Technology (MIT). “Why did life take so long?” “One argument is that we need some sort of stabilization mechanism to maintain a habitable temperature. But the data has never shown that such a mechanism consistently controls Earth’s climate.”

The team believes silicate weathering is a crucial mechanism here: as silicate rocks weather and break up over time, deeper layers of the mineral are continually exposed to the atmosphere. Chemical reactions with silicates remove carbon dioxide from the atmosphere, trapping it in rocks and ocean sediments. Higher levels of carbon dioxide entering the atmosphere increase the amount of silicates released, increasing decomposition, which removes more greenhouse gases from the atmosphere and limits future weather events.

Of course, the timescales of temperature stabilization match the timescales at which silicate weathering operates, up to about 400,000 years. Records left by fossils and ice cores show that this weathering did indeed keep temperatures in check.

The researchers suggest that without this geological feedback mechanism, our planet would experience increasingly extreme temperature fluctuations. Knowing how it works is essential to understanding the past and future of the planet.

“It’s like your car speeding down the street, and when you hit the brake, you’re skidding for a long time before you stop,” says MIT geophysicist Daniel Rothman. “There is a time scale at which the frictional resistance, or compensatory feedback, kicks in when the system returns to a steady state.”

However, something different is happening: When the team looked at longer time scales, over a million years, no such stabilizing feedback was observed in the data. Chances are likely to still play a large part in why life goes on. The researchers conclude that while silicate weathering was (relatively) sufficient to provide short-term stabilization, we were fortunate that long-term temperature fluctuations were not severe enough to interrupt this feedback loop.

Of course, the findings also affect predictions about the future of the planet. It may be possible for life on Earth to withstand the damage humans have done to it, but we may not be around long enough to see it.

“On the one hand, that’s good because we know that today’s global warming will eventually be offset by this stabilizing feedback,” says Arnscheidt. “But on the other hand, it would take hundreds of thousands of years, so it’s not fast enough to solve today’s problems.” Source