Is Anyone Home?

Your guide to exoplanet habitability 

(for life as we know it) 


Carbon Cycle Feedback

This process, which involves volcanoes, oceans, atmosphere, geology and other factors, controls how much carbon dioxide (CO2) is in the atmosphere.

Like a thermostat, the carbon cycle maintains the perfect temperature for life by balancing CO2 levels. 

As a greenhouse gas, it directly affects how much of the star’s heat the atmosphere retains.

Plate Tectonics

As the plates move into the planet’s interior, they carry important elements that have settled on the seafloor. 

These elements are then brought back to the surface by volcanic activity and the creation of new plates.  


Volcanoes bring important elements like CO2, nitrogen and water from deep within a planet to the surface in a process called mantle outgassing. Not only are these elements important for life, but as a greenhouse gas CO2 also helps the atmosphere retain heat.

Without volcanic activity putting CO2 in a planet’s atmosphere, it will likely be too cold for life.

The right level of volcanic activity supports life by delivering important elements to the surface.

With too much ash in an atmosphere, sunlight could be blocked from the surface, affecting life. 

At 1-10 million times Earth’s current volcanic activity, lakes of lava may form on the surface. 


Based on “Impact of Space Weather on Climate and Habitability of Terrestrial Type of Exoplanets,” Airapetian et al. (2019). Specific contributions from Ravi Kumar Kopparapu, Wade Henning and Joshua Schlieder.