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How alien civilizations deal with climate is a measure of how smart they are. Just sayin'...

Did, did these bio-boffins just sass us?

A team of scientists has proposed a new classification system that grades how advanced alien civilizations are by examining how an exoplanet uses energy.

No concrete evidence of advanced life has been found beyond Earth, but that doesn't stop scientists entertaining the idea of extraterrestrial societies.

The new system is a step forward from the Kardashev scale. Nikolai Kardashev, a Russian astrophysicist, argued that the amount of energy that could potentially be used by a planet's inhabitants was a good indication of how technologically advanced the society was.

It's broken down into three types:

  • A Type 1 civilization uses up all of the energy that reaches its planet from its parent star.
  • A Type 2 civilization is capable of harnessing all the energy emitted by its star and planetary system.
  • A Type 3 civilization is very advanced and uses all the energy of its home galaxy.

A paper published this month in Anthropocene describes a new classification system that instead looks at how the use of energy relates to how alien civilizations might arise, and how they sustain themselves over time.

Adam Frank, coauthor of the paper and a professor of physics at the University of Rochester, New York, said: "The Kardashev scale is concerned with extracting energy. But what we've recognized with our classification scheme is that you can't use energy without causing different kinds of waste. That waste feedbacks on the state of the planet."

The idea is that it takes time for societies to become advanced, and they will have to find new ways to utilize energy to preserve themselves. On Earth, most of the energy comes from fossil fuels, but over time as we have advanced, our planet has undergone rapid change. Deforestation, air pollution, and the increased demand for electrical power has damaged Earth. If the human race is to survive, it must find new ways of harvesting energy more sustainably.

"You can't just bring a planet to heel, you need to bring it a plan and figure out how to extract energy while also maintaining the health of the planet's biosphere," Frank said. "Human beings are part of the biosphere, so they need to work with it in order to take the next steps in planetary evolution."

The new ranking system uses five different classes to determine how advanced the alien world is:

  • Class I: The planet does not have an atmosphere. The atmosphere has a strong impact on the possible climates on the planet, and without one the ability for life to change and evolve is restrained, like Mercury.
  • Class II: The planet has an atmosphere, but no life. The flow of energy from gases and fluids creates dynamic climate and weather systems, like Venus.
  • Class III: The planet has a light atmosphere, and exhibits some biological activity. But it has little effect on the planet. There are currently no planets in the Solar System that would fall under this category.
  • Class IV: The planet has a complex biosphere that affects the flow of energy coming from the Sun and beyond. Life is complex, and has a strong effect on the processes happening on the planet. The ecosystem evolves with the planet over time. Earth is considered a Class IV planet.
  • Class V: The planet enters a relationship with its biosphere to use the energy available in a way that is sustainable. The productivity of the biosphere increases, and civilization evolves and advances.

"The universe has created a lot of opportunities for what's happening to us to have happened before," Frank said. "We're starting off by assuming there have been Class V planets."

The researchers believe Earth may reach Class V in the future, if it comes up with new techniques to harness energy without damaging the environment. It will involve becoming more green. More trees will need to be planted to soak up carbon dioxide and pump out oxygen, or even creating genetically modified trees with leaves that can convert the sun's energy into electricity.

Frank warned of a bleak future if the civilizations failed to advance to Class V. He said: "Civilization arose as part of a biosphere. A Type 2 civilization on the Kardashev scale that is super space-baring could live without a biosphere.

"But a young civilization, like ours, has to see itself as a part of the biosphere. We're not separate from it, we're just the latest experiment the earth is running in the evolution of life. If we're not careful, it will just move on without us." ®

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