Scientists believe that advanced civilizations face the same problems and therefore aliens may be doomed to extinction just like humans.
Earth's average global temperatures have been rising steadily since the industrial revolution. According to the National Oceanic and Atmospheric Administration (NOAA), Earth has been warming at a rate of 0.06 °C (0.11 °F) per decade since 1850—or about 1.11 °C (2 °F) in total. Since 1982, the average annual augment has been 0.20 °C (0.36 °F) per decade, more than three times faster.
What’s more, this trend is predicted to augment by 1.5–2 °C (2.7–3.6 °F) by mid-century, and perhaps even more! This is a direct result of the burning of fossil fuels, which has increased exponentially since the mid-19th century, reports universetoday.com.
Depending on the extent of the temperature rise, the impact on Earth’s habitability could be catastrophic. In a recent study, a team of scientists explored how rising temperatures are a long-term problem for advanced civilizations, not just a matter of fossil fuel consumption.
They say rising planetary temperatures could be an inevitable result of exponential growth in energy consumption. Their findings could have major implications for astrobiology and the Search for Extraterrestrial Intelligence (SETI) program.
The study was conducted by Amedeo Balbi, assistant professor of astronomy and astrophysics at the Universita di Roma Tor Vergata, and Manasvi Lingam, assistant professor in the Department of Aeronautics, Physics and Space Sciences and the Department of Chemistry and Chemical Engineering at the Florida Institute of Technology (Florida Tech).
In an article detailing their findings:Waste Heat and Habitability: Constraints from Technological Energy Use”, recently appeared online and is currently under peer review for publication in the journal Astrobiology.
The idea that civilizations will eventually overheat their planet goes back to the work of Soviet scientist Mikhail I. Budyko. In 1969, he published a groundbreaking study titled “The Effect of Solar Radiation Changes on the Earth’s Climate,” in which he argued that “All the energy used by man is converted into heat, the major part of this energy being an additional source of heat compared with the current radiation gain.
Simple calculations show that at the current rate of growth in energy use, human-generated heat will be comparable to the energy from the Sun in less than two hundred years.
This is a simple consequence of the fact that all energy production and consumption invariably produces waste heat. While this waste heat is only a marginal contributor to global warming compared to carbon dioxide emissions, long-term projections suggest that this may change. As Lingam told Universe Today via email:
“The current contribution of waste heat to global temperature increases is minimal. However, if waste heat production continues to increase exponentially over the next century, an additional 1 degree Celsius (1.8 F) of temperature increase could result from waste heat, regardless of the greenhouse effect from fossil fuels. If waste heat generation continues to increase exponentially over the centuries, we show that this could ultimately lead to the complete loss of habitability and the extinction of all life on Earth.”
The Dyson sphere is a fitting example of the waste heat resulting from the exponential growth of an advanced civilization. In his original paper, “Search for Artificial Stellar Sources of Infrared Radiation,” Freeman Dyson argued that the need for more habitable space and energy could eventually lead a civilization to create “an artificial biosphere that completely surrounds its parent star.”
As he described, these megastructures would be detectable by infrared instruments due to “large-scale conversion of starlight into far-infrared radiation,” meaning they would emit waste heat into space.
“The heating we study in our paper is the result of the conversion of any form of energy and is an inevitable consequence of the laws of thermodynamics,” added Balbi, the study’s lead author. “For today’s Earth, this heating is only a tiny fraction of the warming caused by the anthropogenic greenhouse effect. However, if global energy consumption continues to increase at its current rate, this effect could become significant within a few centuries, potentially affecting Earth’s habitability.”
To determine how long it would take for advanced civilizations to reach the point where they would render their planet uninhabitable, Balbi and Lingam developed theoretical models based on the Second Law of Thermodynamics (as applied to energy production). They then applied them to planetary habitability, taking into account the circumsolar habitable zone (CHZ)—i.e., orbits where a planet would receive enough solar radiation to support liquid water on its surface.
“We have adapted the habitable zone calculations, a standard tool in exoplanetary studies. We have basically included an additional heating source — from technological activity — in addition to stellar radiation,” Balbi said.
Another key factor they took into account is the exponential growth of civilizations and their energy consumption, as predicted by the Kardashev Scale. Using humanity as a template, we see that global energy consumption increased from 5,653 terawatt-hours (TWh) to 183,230 TWh between 1800 and 2023.
Not only was this trend exponential, it accelerated over time, as did population growth over the same period (1 billion in 1800 to 8 billion in 2023). Balbi and Lingam extrapolated this trend to measure the implications for habitability and determine the maximum lifespan of an advanced civilization once it entered a period of exponential growth.
Ultimately, the scientists concluded that the maximum lifetime of technospheres is about 1,000 years, provided that they grow at an average annual rate of about 1% throughout the study period.
According to Balbi, these discoveries have implications for humanity and the SETI (Search for Extraterrestrial Intelligence) program:
“Our results suggest that the impact of waste heat could become significant not only in the future of Earth, but also in the development of hypothetical technological species inhabiting planets around other stars. Consequently, taking this constraint into account could affect how we approach the search for advanced technological life in the universe and how we interpret the results of such searches. For example, it could provide a partial explanation for the Fermi paradox.”
Balbi and Lingam also point out that these results offer some possible recommendations for how we might avoid making our planet uninhabitable. Once again, there are implications for SETI, since any solution we can imagine has likely already been implemented by another advanced species. Balbi said:
“Although our work focuses on physics rather than solutions to societal challenges, we envision several scenarios that could help a technological species mitigate the constraints of waste heating and delay its onset. A sufficiently advanced civilization could use technology to counteract heating, such as by using stellar shields.”
“Alternatively, they could move much of their technological infrastructure off-world, moving into space. Such engineering megaprojects would have significant implications for our search for technosignatures. A less ambitious but perhaps more feasible approach would be to reduce energy consumption by slowing growth. Of course, we can't predict which of these options is most likely.”
Source: www.universetoday.com
Image Source: Pixabay.com
