March 1, 2024

Lukmaan IAS

A Blog for IAS Examination




THE CONTEXT: Recent research suggests that variations in CO2 levels among neighbouring planets could offer clues about a planet’s potential habitability, particularly in relation to the presence of liquid water.


  • The presence of carbon dioxide (CO2) in a planet’s atmosphere has been studied extensively due to its role in absorbing infrared radiation, a factor contributing to rising temperatures on Earth.

Significance of CO2 Absorption

  • CO2 in a planet’s atmosphere functions as a significant absorber within the infrared region of the light spectrum.
  • This property contributes to the greenhouse effect and subsequent temperature elevation observed on Earth.
  • A lead researcher in exoplanetology, highlights that measuring CO2 levels within planetary atmospheres provides crucial data for identifying potential liquid water sources.

Identifying Planetary Habitability

  • The research, led by the University of Birmingham in the UK and MIT in the US, introduces a novel ‘habitability signature.’
  • This signature revolves around assessing CO2 disparities among planets, suggesting a potential absorption of this gas by oceans or its isolation via planetary-scale biomass.
  • The habitability zones around stars define regions where planets can maintain conditions suitable for liquid water on their surfaces.
  • Planets falling within these zones—neither too close nor too far from their host stars—are deemed potentially habitable.
  • Comparing CO2 concentrations across planets offers insights into potential liquid water presence.
  • Lower CO2 levels relative to neighbouring planets indicate the likelihood of oceans or biomass influencing CO2 absorption, hinting at the capacity to support life.

CO2, Earth’s Evolution, and Habitability

  • Earth’s history serves as an example, having transitioned from an atmosphere dominated by CO2 to one conducive to life due to carbon dissolution in oceans over billions of years.
  • This evolution points to the possibility of similar processes occurring on other habitable planets.

Environmental Tipping Points and Uninhabitability

  • Examining CO2 levels on other planets provides a platform to understand environmental tipping points.
  • For instance, Venus, despite resembling Earth in some aspects, became uninhabitable due to exceedingly high carbon levels in its atmosphere, hinting at potential past climatic tipping points.

CO2 as a Biosignature

  • The devised ‘habitability signature’ extends beyond merely assessing potential liquid water sources.
  • It can serve as a biosignature, indicating the presence of life. Living organisms’ carbon consumption often results in the emission of oxygen, which can transform into ozone.
  • Detecting both CO2 and ozone simultaneously can provide evidence of habitability and potential life on a planet.


  • This innovative method of analyzing CO2 levels among planets offers a promising approach to identifying habitable environments and potential signs of life beyond Earth.
  • Understanding the relationship between CO2, liquid water, and potential biosignatures can provide invaluable insights into the habitability of exoplanets and the search for extraterrestrial life.


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