The dramatic influence of human activity on Earth could now be pushing our planet into a state of ‘hybridization,’ before it shifts into another planetary class entirely, according to a new study.
As scientists continue to search for alien life, many ideas of advanced civilizations are guided by the Kardashev scale, a system first devised in 1964 that sorts these worlds based on the energy their hypothetical inhabitants have harnessed.
In a new study, however, researchers have developed a new classification scheme that takes this even further, relying on the idea that a planet’s energy flow can be pushed out of sync by the beings that dwell on it.
The dramatic influence of human activity on Earth could now be pushing our planet into a state of ‘hybridization,’ before it shifts into another planetary class entirely, according to a new study
NEW PLANETARY CLASSIFICATIONS
Class I – Worlds with no atmosphere at all, such as the planet Mercury and the Earth’s moon
Class II – Planets with a thin atmosphere containing greenhouse gases, but no current life, such as the current states of Mars and Venus
Class III – Planets have perhaps a thin biosphere and some biotic activity, but much too little to ‘affect planetary drivers and alter the evolutionary state of the planet as a whole.’ No current examples exist in the solar system, but early Earth may have represented such a world—and possibly early Mars, if life ever existed there
Class IV – Planets have a thick biosphere sustained by photosynthetic activity and life has begun strongly affecting the planetary energy flow.
Class V – Planet is profoundly affected by the activity of an advanced, energy-intensive species
– University of Washington, via Earth as a Hybrid Planet: Anthropocene in an Evolutionary Astrobiological Context
By this system, the experts argue that Earth could be transitioning from a Class IV planet, in which biotic activity has begun to have substantial effects on the energy flow, to the final category, Class V.
In this category, the ‘energy-intensive species,’ has had profound effects.
Earth is now considered to be in a period known as the Anthropocene, an epoch marked by human impact.
And, according to the researchers, this activity is even influencing the planet-wide evolution.
‘Our premise is that Earth’s entry into the Anthropocene represents what might, from an astrobiological perspective, be a predictable planetary transition,’ the researchers from the University of Rochester and the University of Washington write in the paper, published in the journal Anthropocene.
‘We explore this problem from the perspective of our own solar system and exoplanet studies.
‘In our perspective, the beginning of the Anthropocene can be seen as the onset of the hybridization of the planet – a transitional stage from one class of planetary systems to another.’
The new classification system is based on ‘non-equilibrium thermodynamics,’ according to the researchers.
This means the magnitude to which energy flow becomes out of sync as ‘different planetary processes – abiotic, biotic, and technologic – generate free energy, i.e. energy that can perform work within the system.’
All in all, there are five categories among which planets can be assigned.
Earth is now considered to be in a period known as the Anthropocene, an epoch marked by human impact. And, according to the researchers, this activity is even influencing the planet-wide evolution
The Kardashev scale, named for Soviet astronomer Nikolai Kardashev, was propsed in 1964 to describe a ciilization’s level of technological advancement, based on the amount of energy it harnesses.
Type I – Civilization could manipulate all the energy resources of its home planet
Type II – Civilization harnesses all the energy in its star/planetary system
Type III – Super-advanced civilization would command the energy of its whole home galaxy
Several extensions have also been proposed over the years, allowing for up to seven categories.
-University of Washington
The first class includes worlds with no atmosphere at all. This includes Mercury and Earth’s moon.
The second class represents those with a thin atmosphere containing greenhouse gases, but no current life, such as Mars and Venus.
Class III planets, on the other hand, may have a thin biosphere and some biotic activity, but not enough to affect the planet’s evolutionary state.
According to the researchers, there are no current examples of this in our solar system, though early Earth and even Mars (if it ever truly hosted life) may once have been categorized as such.
The fourth class of planets have a thick biosphere, and the photosynthetic activity and life at the surface has begun to have dramatic effects on the energy flow.
In Class V, the ‘energy-intensive species,’ has had profound effects on the evolutionary state of the planet.
While the system could be helpful in the search for advanced alien civilizations, the researchers stress the importance of applying this understanding to our own home.
‘The discovery of seven new exoplanets orbiting the relatively close star Trappist-1 forces us to rethink life on Earth,’ said Marina Alberti, of the University of Washington.
While the system could be helpful in the search for advanced alien civilizations, the researchers stress the importance of applying this understanding to our own home. An artist’s impression of the Trappist-1 system is pictured
‘It opens up the possibility to broaden our understanding of coupled system dynamics and lay the foundations to explore a path to long-term sustainability by entering into a cooperative ecological-evolutionary dynamic with the coupled planetary systems.’
The new system could also provide the basis for future works on the co-evolution of planets where an energy-intensive civilization drives major planetary effects.
These planets, they argue, must be considered on a continuum of these interactions.
‘Any world hosting a long-lived energy-intensive civilization must share at least some similarities in terms of the thermodynamic properties of the planetary system,’ the authors wrote.
‘Understanding these properties, even in the broadest outlines, can help us understand which direction we must aim our efforts in developing a sustainable human civilization.
Or, put simply, ‘If one does not know where one is going, it’s hard to get there.’