Earth as hybrid planet: New classification places Anthropocene era in astrobiological context
https://phys.org/news/2017-09-earth-hybrid-planet-classification-anthropocene.html
For decades, as astronomers have imagined advanced extraterrestrial civilizations, they categorized such worlds by the amount of energy their
inhabitants might conceivably be able to harness and use. They sorted the hypothetical worlds into three types according to a scheme named in
1964 for Soviet astronomer Nikolai Kardashev.
Now, a team of researchers including Marina Alberti of the University of Washington has devised a new classification scheme for the evolutionary
stages of worlds based on "non-equilibrium thermodynamics"—a planet's energy flow being out of synch, as the presence of life could cause.
The categories range from imagined planets with no atmosphere whatsoever to those with an "agency-dominated biosphere" or even a "technosphere,"
reflecting the achievements of a vastly advanced, "energy-intensive technological species."
Their paper, "Earth as a Hybrid Planet: The Anthropocene in an Evolutionary Astrobiological Context," was published Sept. 6 in the journal
Anthropocene. Lead author is Adam Frank, professor of physics and astronomy at the University of Rochester. Alberti is a professor of urban
design and planning in the UW College of Built Environments, and director of the college's Urban Ecology Research Lab.