They discover that the Earth has been regulating its own temperature for thousands of years.

A study led by researchers at the Massachusetts Institute of Technology (MIT) in the United States and published in 2014. Science Advances confirms it The planet harbors a “compensatory feedback” mechanism that has been working for billions of years to steer the climate away from the most devastating extremes, keeping global temperatures within a stable and habitable range.

How does the world achieve this? Most likely, it is a mechanism called “silicate weathering”, a geological process in which the slow and steady weathering of silicate rocks causes chemical reactions that eventually pull carbon dioxide from the atmosphere and deposit it in the soil. in the rocks.

Scientists have long suspected this. silicate weathering plays an important role in regulating Earth’s carbon cycle. This mechanism could provide a geologically stable force to keep carbon dioxide and global temperatures in check. However, direct evidence of this continuous feedback mechanism has not been found before.

The new findings are based on a study of paleoclimate data that records changes in average global temperatures over the past 66 million years. The MIT team applied mathematical analysis to see if the data revealed any characteristic patterns of stabilizing events in global temperatures over a wide time scale.

Ends are cyclically damped

In fact, they discovered There seems to be a consistent pattern in which Earth’s temperature changes decrease over periods of hundreds of thousands of years.. The duration of this effect coincides with the time periods during which the dissociation of silicates will act predictably.

This stabilizing feedback would explain why Earth remained habitable for millions of years and despite extreme weather events in the geological past.

“On the one hand, That’s good because we know that current global warming will eventually be canceled out by this balancing feedback.“Constantine Arnscheidt, of MIT’s Department of Planetary, Atmospheric and Earth Sciences,” says. It will take hundreds of thousands of years, so it won’t be fast enough to solve our current problems.”

Scientists have previously seen hints of a climate stabilizing effect on Earth’s carbon cycle. Chemical analysis of ancient rocks has shown that carbon flux into and out of Earth’s surface environment remains relatively stable, even despite dramatic changes in global temperature.

“You have a planet whose climate has been subject to many extreme weather changes. Why has life survived so long? The explanation is that we need some kind of stabilizing mechanism to maintain temperatures suitable for life,” says Arnscheidt. “But The mechanism that consistently controls the Earth’s climate has never been demonstrated in concrete data.”

66 million years of data

The researchers studied various global temperature records compiled by other scientists from preserved Antarctic ice cores, as well as the chemical composition of ancient marine fossils and shells.

“This whole work is only possible because great strides have been made in improving the resolution of these deep-sea temperature records,” says Arnscheidt. “We now have data going back 66 million years, with data separated by thousands of years at most.”

The team applied the mathematical theory of stochastic differential equations to this data.It is commonly used to reveal patterns in widely fluctuating datasets.

“We realized that this theory predicts what the Earth’s temperature history would look like if there were feedbacks acting on certain time scales,” Arnscheidt said.

Using this system, the team looked at the history of average global temperatures over the past 66 million years and looked at the entire period over different time scales, such as tens of thousands of years to hundreds of thousands of years, to see if temperature patterns emerged. • Balancing feedback on each time scale.

SWithout these stabilizing feedbacks, global temperature fluctuations will grow larger over time.. But the study by the researchers showed that these fluctuations did not grow; which implies that a stabilizing mechanism in the climate is at work before these changes become too extreme. The timescale of this stabilizing effect (hundreds of thousands of years) matches the scientists’ estimates for silicate weathering.

Longest timescales, luckily

Interestingly, the scientists discovered that on longer time scales the data did not show any compensatory feedback.. That is, there doesn’t seem to be any repeating reversal in global temperatures on time scales greater than a million years. So, in these longer periods,What keeps global temperatures in check?

“There is an idea that Chance may have played an important role in determining why life still exists more than 3 billion years later.“, says MIT professor Daniel Rothman, co-author of the study.

In other words, because Earth’s temperatures fluctuate over longer periods of time, these fluctuations may be small enough, in geological terms, to be within a range where stabilizing feedback such as silicate weathering can occur. , within a habitable zone.

“There are two camps: some say random chance is a good enough explanation, and others say there should be compensatory feedback,” says Arnscheidt. “From direct data, we can show that the answer is probably somewhere in the middle. In other words, some stability was achieved, but luck likely played a role in keeping Earth permanently habitable.”

Reference work: https://www.science.org/doi/10.1126/sciadv.adc9241

……..

Contact address of the environment department: [email protected]