The researchers define true planetary intelligence as the point at which all the living systems on a planet work in unison for the benefit of the entire system. This would involve feedback loops in which negative changes to the planet, such as rapid climate change, are identified and counteracted.
“We consider planetary intelligence to be life's collective response to changes in the state of the entire planet," the researchers wrote. "The collective result is that life doesn't doom itself over time."
However, this does not happen overnight, and there are major obstacles planets must overcome before they can be deemed intelligent. In the new study, the researchers propose four main stages in planetary intelligence: immature biosphere, mature biosphere, immature technosphere and mature technosphere.