CO2 levels in planet atmosphere could be a sign of its habitability: study

New research reveals a "habitability signature" to detect liquid water on planets, potentially aiding in the search for life.

New research shows that a lower amount of the carbon dioxide gas in a planet’s atmosphere compared to that of its neighbours could hint the presence of liquid water on that planet.

Researchers said the drop in the carbon dioxide levels relative to the neighbouring planets implied a possible absorption of the gas by an ocean or isolation by biomass on a planetary scale.

While multiple studies have made attempts to identify planets lying in the habitable zones of the stars they orbit, the researchers said until now there was no way of knowing whether they truly have liquid water.

The international team of researchers, led by the University of Birmingham in the U.K., and Massachusetts Institute of Technology (MIT) in the U.S., said that they had devised a new ‘habitability signature’ and that it was a “practical method for detecting habitability”.

They have published their findings in the journal Nature Astronomy.

Planets that are neither too close to their star and thus too hot, nor too far from their star and thus too cold are considered to be in the just right ‘habitable zone’. The planets could therefore be ‘habitable’ and capable of hosting and retaining liquid water on its surface.

The carbon dioxide, or CO2, in a planet’s atmosphere is a strong absorber in the infrared region of the light spectrum, the same property through which it is currently causing the earth’s temperatures to rise, explained co-lead researcher Amaury Triaud, Professor of Exoplanetology at the University of Birmingham.