Detecting industrial pollution in the atmospheres of earth-like exoplanets

TL;DR

This paper proposes using anthropogenic pollutants like CFCs as novel biosignatures for detecting intelligent extraterrestrial life via atmospheric analysis with JWST.

Contribution

It introduces the concept of anthropogenic pollution as a biosignature and identifies detectable CFCs in exoplanet atmospheres using JWST spectral data.

Findings

Detection of CCl3F and CF4 is feasible within a few days of observation.

Pollutant concentrations can be constrained to about 10 times terrestrial levels.

Anthropogenic pollutants could serve as indicators of intelligent life on exoplanets.

Abstract

Detecting biosignatures, such as molecular oxygen in combination with a reducing gas, in the atmospheres of transiting exoplanets has been a major focus in the search for alien life. We point out that in addition to these generic indicators, anthropogenic pollution could be used as a novel biosignature for intelligent life. To this end, we identify pollutants in the Earth's atmosphere that have significant absorption features in the spectral range covered by the James Webb Space Telescope (JWST). We focus on tetrafluoromethane CF4 and trichlorofluoromethane (CCl3F), which are the easiest to detect chlorofluorocarbons (CFCs) produced by anthropogenic activity. We estimate that ~1.2 days (~1.7 days) of total integration time will be sufficient to detect or constrain the concentration of CCl3F (CF4) to ~10 times current terrestrial level.