It could take less than 1,000 years for an advanced alien civilization to destroy its planet with climate change, even if it relies solely on renewable energy, a new model suggests.
When astrophysicists simulated the rise and fall of foreigner civilizations, they found that, if a civilization experienced exponential technological growth and energy consumption, it would be less than 1,000 years before the alien planet became too hot to be habitable. This would be true even if civilization used renewable energy sources, due to the inevitable leakage in the form of heat, as predicted by the laws of thermodynamics. The new research was posted to the database ahead of print arXiv and is in the process of peer review.
As astrophysicists wanted to understand the implications for life beyond our planet, their study was initially inspired by human energy use, which has grown exponentially since the 1800s. In 2023, humans used about 180,000 terawatt hours (TWh), which is roughly the same amount of energy that hits Earth from the sun at any given moment. Much of this energy is produced by gas and coal, which is warming the planet at an unsustainable rate. But even if all this energy were generated from renewable sources such as wind and solar energy, humanity would continue to grow, and thus continue to need more energy.
“It raised the question, ‘Is this something that is sustainable over a long period of time?’ Manasvi Lingaman astrophysicist at Florida Tech and a co-author of the study, told Live Science in an interview.
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Lingam and his co-author Amedeo Balbian associate professor of astronomy and astrophysics at Tor Vergata University of Rome, were interested in applying the second law of thermodynamics to this problem. This law states that there is no perfect energy system, where all the energy created is used efficiently; some energy must always escape from the system. This saved energy will cause a planet to heat up over time.
“You can think of it as a dripping bathtub,” Lingam said. If a bathtub that holds only a little water leaks, only a small amount can escape, he explained. But as the tub fills more and more—as energy levels increase exponentially to meet demand—a small leak can suddenly turn into a flooded house.
In this case, the flooded house is the atmospheric temperature of a planet. An accumulation of energy leaks, even from green energy, will eventually overheat any planet to the point where it is no longer habitable. If energy levels are not curbed, this catastrophic level i climate change it could take less than 1,000 years to start producing energy, the team found.
For astrobiologists, this 1,000-year limit also makes finding life elsewhere in the cosmos much more difficult. After all, 1,000 years is a blink of an eye in cosmic terms, with planets like Earth taking hundreds of millions of years to become habitable in the first place. But alien extinction isn’t the only possible outcome of exponential energy use, Lingam said.
However, there are other possibilities, both for humans and alien civilizations. Rather than accept extinction or develop the technology to move energy production off-world, a civilization might choose to flatten their growth, Lingam suggested.
“If a species has chosen the balance, learned to live in harmony with its surroundings, that species and its descendants can survive for perhaps a billion years,” he said.
