The Permian-Triassic extinction event, also known as The Great Dying, certainly earned its nickname. It was the largest mass extinction in the geologic record, wiping out between 83 and 97 percent of all species living on Earth. While the exact cause is debated, the extreme volcanic activity that may have cooked the planet has been pinpointed as the main culprit.
But somehow, despite being ravaged by asteroids and space radiation, life on this planet has persisted for nearly four billion years. As our planet faces a sixth mass extinction, driven by a wave of human activity that has wiped out thousands of species, the question arises as to how this works—in particular, how Earth appears to recover from large-scale disasters or extreme changes in atmosphere or climate— becomes even more urgent.
It turns out that the answer is, in part, even stranger than anyone imagined. New research in the journal Science Advances suggests the Earth can self-regulate its temperature for hundreds of thousands of years. In other words, there are large-scale geological processes that seem to absorb carbon dioxide over enormous timescales. However, the timescales involved are far, far too long to correct for the sudden spike in carbon dioxide caused by the burning of fossil fuels, meaning the mechanism won’t save us from climate change.
“You have a planet whose climate has been subject to so many dramatic external changes. Why has life survived all this time?”
Constantin Arnscheidt and Daniel Rothman, two researchers at the Massachusetts Institute of Technology in Cambridge, processed the data from multiple datasets documenting Earth’s temperature over the past 66 million years. These paleoclimate records include ice cores from Antarctica and the chemical composition of prehistoric marine fossils, which can tell us a lot about what Earth’s atmosphere looked like in the distant past.
“This whole research is only possible because great progress has been made in improving the resolution of these deep-sea temperature records,” Arnscheidt said in a statement. “Now we have data going back 66 million years, with data points that are at most thousands of years apart.”
The two MIT scientists found a strong pattern that suggests Earth uses feedback loops to keep temperatures within a range where life can thrive. However, this is happening on a timescale of hundreds of thousands of years, so while it implies our planet will recover from anthropogenic climate change, it won’t happen fast enough to save us.
“One argument is that we need some sort of stabilizing mechanism to keep temperatures suitable for life,” Arnscheidt said. “But data has never shown that such a mechanism has consistently controlled Earth’s climate.”
The finding has major implications for our understanding of the past, as well as how global warming is shaping the future of our homeworld. It even helps us better understand the evolution of planetary temperatures, which could make the search for alien-inhabited exoplanets more fruitful.
“You have a planet whose climate has been subject to so many dramatic external changes. Why has life survived all this time? One argument is that we need some sort of stabilizing mechanism to keep temperatures suitable for life,” Arnscheidt said. “But data has never shown that such a mechanism has consistently controlled Earth’s climate.”
Many scientists have proposed that the Earth has self-regulated its temperature throughout history, but this has been difficult to prove. In the 1960s, the late inventor and environmentalist James Lovelock applied Darwinian processes to the entire planet, rather than to a single organism, to explain how such a complex system evolved. He called this the Gaia hypothesis, which explains how Earth and its biological systems formed feedback loops that keep our planet favorable for living organisms.
It also helped explain the Faint-Sun Paradox, first proposed by astronomers Carl Sagan and George Mullen in 1972. Essentially, our sun was a lot smaller and colder 4.5 billion years ago. At the time, based on our current understanding of the life cycle of stars, the sun would have been about 30 percent fainter than it is now. This, in turn, would have made the Earth too cold for liquid water, preventing life from forming – but this clearly happened. So how did our rocky world manage to do this?
The answer appears to lie in how carbon is cycled through the planet. One prominent theory is that when our planet first formed, it had an atmosphere brimming with carbon dioxide, a potent greenhouse gas, that allowed it to absorb heat even though the sun was colder.
“On the one hand, it’s good because we know that today’s global warming will eventually be negated by this stabilizing feedback. But on the other hand, it will take hundreds of thousands of years for it to happen, so not fast enough for our current solve the problem.” -day problems.”
A complex process known as silicate weathering then removes carbon dioxide from the atmosphere and buries it at the bottom of the ocean. Over time, this cools the planet. Then something like big volcanic eruptions or people driving cars pump more carbon dioxide into the air, warming the planet again. Over the centuries, Earth seems to balance between too cold and too hot, which explains why some call Earth a Goldilocks planet.
The MIT study helps match existing data with this long-held theory, which helps us better understand our past and the impacts of uncontrolled climate change. And it would make sense that if these feedback loops exist on our planet, they could exist in other galaxies, informing the hunt for extraterrestrial life.
“On the one hand, it’s good because we know that today’s global warming will eventually be outweighed by this stabilizing feedback,” Arnscheidt said. “But on the other hand, it will take hundreds of thousands of years for it to happen, so not fast enough to solve our current problems.”
However, Arnscheidt’s model was unable to account for this equilibrium on timescales of more than a million years, so random chance may also have played an inordinate role in the success of life on this rock.
“There are two camps: some say random chance is a good explanation, and others say there should be a stabilizing feedback,” Arnscheidt said. “We can show directly from data that the answer is probably somewhere in between. In other words, there was some stabilization, but sheer luck probably also played a role in keeping Earth continuously habitable.”
It may have been a mix of randomness and feedback loops, such as silicate weathering affecting Earth’s temperature in the past. But in humanity’s future, it will be free will – our policies, our consumption, our choices – that will determine the temperature of the planet in the future. And we can so overwhelm these natural systems that they won’t be able to balance out, similar to prominent theories of potential life on Mars.
“The warming of the sun has been slow enough for life to evolve, a process that takes millions of years. Unfortunately, the sun is now too hot for the further development of organic life on Earth,” Lovelock wrote in his 2019 book ” Novacene: The Coming Age of Hyperintelligence.” “Our star’s output of heat is too great to restart life, as it did with the simple chemicals of the Archean period between 4 billion and 2.5 billion years ago. If life on Earth is wiped out, it will not start it again.”
about this subject