Is the Earth a self-organizing organism? A new study suggests that our planet contains an internal climate control
The Permian-Triassic extinction event, also called the Great Dying, certainly earned its nickname. It was the largest mass extinction in the geological record, wiping out between 83 and 97 percent of all species living on Earth. Although the exact cause is under debate, intense volcanic activity that may have cooked the planet has been cited as the main culprit.
But somehow, despite being attacked by asteroids and space radiation, life continued on the planet for about four billion years. As our planet enters its sixth mass extinction, spurred on by a wave of human activity that has wiped out thousands of species, the question of how this might work–in particular, how Earth seems to bounce back from large-scale disasters, or extreme changes in the atmosphere or climate–becomes more intense. Urgently.
It turns out that the answer may be, in part, even stranger than anyone imagined. New research in the journal Science Advances suggests that the Earth could self-regulate its temperature over hundreds of thousands of years. In other words, there are large-scale geological processes that seem to be absorbing carbon dioxide over huge time scales. However, the time scales involved are too long to correct for the spike in carbon dioxide caused by fossil fuel combustion, which means that the mechanism will not save us from climate change.
“You have a planet whose climate has undergone many dramatic external changes. Why has life survived so long?”
Constantin Arnscheidt and Daniel Rothman, researchers from the Massachusetts Institute of Technology in Cambridge, studied data from multiple data sets documenting global temperature over the past 66 million years. These paleoclimate records include ice samples from Antarctica and the chemical composition of prehistoric marine fossils, which can tell us a lot about what Earth’s atmosphere was like in the distant past.
“This entire study is only possible because of the significant advances that have been made in improving the accuracy of deep sea temperature records,” Ernscheidt said in a statement. “Now we have data going back 66 million years, with data points thousands of years apart.”
The two MIT scientists found a strong pattern that suggests Earth uses feedback loops to maintain temperatures within a range in which life can thrive. However, this happens on a timescale over hundreds of thousands of years, so while it is implied that our planet will bounce back from human-induced climate change, it won’t happen soon enough to save us.
“One of the arguments is that we need some kind of stabilization mechanism to maintain temperatures suitable for life,” Arnscheidt said. “However, it is not proven from the data that such a mechanism has consistently controlled the Earth’s climate.”
This discovery has major implications for our understanding of the past, but also for how global warming will shape the future of our homeworld. It even helps us better understand the evolution of planetary temperatures that could make the search for inhabited exoplanets more fruitful.
“You have a planet whose climate has undergone many dramatic external changes. Why has life survived so long? One argument is that we need some kind of stabilizing mechanism to maintain temperatures suitable for life,” said Ernschidt. “However, it is not proven from the data that such a mechanism has consistently controlled the Earth’s climate.”
Many scientists have suggested that the Earth has self-regulated its temperature throughout history, but this has been difficult to prove. In the 1960s, the late inventor and ecologist James Lovelock applied Darwinian processes to the entire planet, rather than to a single organism, to explain how such a complex system could evolve. He called this the Gaia hypothesis, which explains how the Earth and its biological systems have formed feedback loops that keep our planet suitable for living organisms.
They also helped explain the dim sun paradox, first proposed by astronomers Carl Sagan and George Mullen in 1972. Our Sun was essentially much younger and cooler 4.5 billion years ago. At that time, based on our current understanding of the life cycle of stars, the Sun could have been about 30% dimmer than it is today. This, in turn, would make the Earth too cold for liquid water, preventing life from forming—but apparently that happened. So how did our rocky world get away with this?
The answer appears to lie in how carbon is cycled across the planet. One prominent theory is that when our planet first formed, its atmosphere was full of carbon dioxide, a powerful greenhouse gas, which allowed it to absorb heat, even though the sun was much cooler.
“On the one hand, it’s a good thing because we know that global warming today will eventually be canceled out by these stabilizing reactions. But on the other hand, it’s going to take hundreds of thousands of years for that to happen, so it’s not fast enough to solve our present-day issues. “
A complex process known as silicate weathering then removes carbon dioxide from the atmosphere and buries it on the ocean floor. Over time, this cools the planet. Then, something like major volcanic eruptions or humans driving cars pumps more carbon dioxide into the air, warming the planet again. Through the ages, Earth has seemed to balance between extreme cold and extreme heat, which explains why some have called Earth the Goldilocks Planet.
The MIT study helps match current data with this ancient theory, helping us better understand our past and the consequences of uncontrolled climate change. And it stands to reason that if such feedback loops exist on our planet, they may also exist in other galaxies, aiding the search for extraterrestrial life.
“On the one hand, this is a good thing because we know that global warming today will eventually be canceled out by these stabilization reactions,” said Arnschidt. “But on the other hand, it would take hundreds of thousands of years for that to happen, so it’s not fast enough to solve our current problems.”
However, Arnscheidt’s model was not able to account for this balance on time scales longer than a million years, so random chance may also have played a large role in the success of life on this rock.
“There are two camps: some say random chance is a good enough explanation, others say there must be stable reactions,” said Arnschedt. “We are able to show, directly from the data, that the answer is probably somewhere in between. In other words, there was some stability, but pure luck may also have played a role in keeping Earth consistently habitable.”
It may have been a combination of randomness and feedback loops such as silicate weathering that affected Earth’s temperature in the past. But in humanity’s future, it will be free will — our politics, our consumption, our choices — that determines the planet’s future temperature. And we may overwhelm these natural systems so much that they will be unable to balance, similar to prominent theories about possible life on Mars.
“The sun’s heating was slow enough to allow life to develop, a process that takes millions of years. Unfortunately, the sun is now too hot to continue developing organic life on Earth,” Lovelock wrote in his 2019 book. Novacin: The Coming Age of Hyperintelligence.” “The heat output from our star is too great to start life again as it did from the simple chemicals of the Archean era between 4 billion and 2.5 billion years ago. If life on Earth is wiped out, it will never start again. “
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