Scientists Discover Earth Can Regulate Its Own Temperature
“We know that today’s global warming will eventually be reversed through this stabilizing feedback… But on the other hand, it will take hundreds of thousands of years to occur.”
CAMBRIDGE, Mass. — Will climate change really be the end of the world as we know it? There’s a good chance Earth won’t let that happen, a new study reveals.
Scientists from the Massachusetts Institute of Technology have found that the planet has a “stabilizing feedback” system that keeps global temperatures within a stable and habitable range. Although it can take hundreds of thousands of years to complete the process, this mechanism regularly pushes the climate away from the brink of destruction.
“On the one hand, it’s a good thing because we know that today’s global warming will eventually be canceled thanks to this stabilizing feedback,” says Constantin Arnscheidt, graduate student in the Department of Earth Sciences, of the Atmosphere and Planets (EAPS) from MIT, in a university outing. “But on the other hand, it will take hundreds of thousands of years, so not fast enough to solve our current problems.”
The team notes that Earth has experienced a number of dramatic climate changes over the past 3.7 billion years. Despite periods of global volcanic activity and planet-wide ice ages, however, Earth keeps bouncing trayk and still supports life.
So how does the planet regulate its temperature?
The MIT researchers believe the most likely explanation is “silicate weathering” – a geological process where the slow and steady weathering of silicate rocks leads to chemical reactions that extract carbon dioxide from the atmosphere. These particles penetrate the ocean sediments, trapping the gas in the rocks.
Scientists suspect that silicate weathering helps regulate the Earth’s carbon cycle, but this is the first time researchers have found direct evidence of such a feedback system. Previous studies of ancient rocks have shown that the flux of carbon in and out of the Earth’s surface has remained relatively balanced over time, despite dramatic changes in global temperatures.
“You have a planet whose climate has been subjected to so many dramatic external changes. Why has life survived all this time? One of the arguments is that we need some kind of stabilization mechanism to maintain temperatures suitable for life,” says Arnscheidt. “But it has never been shown from data that such a mechanism has consistently controlled Earth’s climate.”
66 million years of data proves that the Earth can cool itself
To confirm that the stabilizing feedback really exists, the team looked at global temperature fluctuations over millions of years. The scientists compiled this data using the chemical composition of ancient marine fossils and shells, as well as samples of preserved Antarctic ice cores.
“This whole study is only possible because there have been great strides in improving the resolution of these deep sea temperature recordsnotes Arnscheidt. “Now we have data going back 66 million years, with data points at most thousands of years apart.”
Arnscheidt and his co-author Daniel Rothman applied a mathematical theory of stochastic differential equations to this temperature data to find patterns in the continuously fluctuating numbers.
“We realized that this theory makes predictions for what you expect The history of Earth’s temperature give the impression that there had been feedbacks acting on certain time scales,” says Arnscheidt.
Using this model, the study authors looked at different timescales, ranging from tens of thousands to hundreds of thousands of years.
“To a certain extent, it’s like your car speeding down the street, and when you brake, you slide for a long time before you stop,” says Rothman, a professor of geophysics at MIT. “There is a time scale on which frictional resistance, or a stabilizing feedback, comes into play, as the system returns to a steady state.”
The researchers say that without stabilization of the feedbacks, changes in global temperatures are expected to continue to increase over time. However, the study found a “regime in which the fluctuations did not develop”. This indicates some kind of mechanism that prevails in extreme weather changes. The timescale of this stabilizing effect appears to extend over hundreds of thousands of years, consistent with scientists’ estimates of silicate weathering.
Stabilizing feedback may be a recent development
Arnscheidt and Rothman say they haven’t found the same planetary retreat for time scales longer than a million years. So what controlled temperatures in prehistoric times?
“There is a notion that chance may have played a major role in determining why, after more than 3 billion years, life still exists,” says Rothman.
“There are two camps: some say chance is sufficient explanation, and others say there must be stabilizing feedback,” adds Arnscheidt. “We are able to show, directly from the data, that the answer is probably somewhere in between. In other words, there has been some stabilization, but sheer luck probably also played a part in keeping Earth permanently habitable.
The results appear in the journal Scientists progress.