SET-E: The Search for Extraterrestrial Environmentalism

TL;DR

This paper proposes a novel method called galactic anthropology to detect extraterrestrial environmentalism by observing ozone layer changes on exoplanets, aiming to estimate how common such movements are in the galaxy.

Contribution

It introduces a new observational approach to identify signs of environmentalism on exoplanets through atmospheric monitoring over long periods.

Findings

Potential to detect environmental movements via ozone layer changes

Method can estimate the occurrence rate of extraterrestrial environmentalism

Feasibility improves with combined observations of multiple systems

Abstract

There is currently no evidence for life on any known exoplanet. Here, we propose a form of "galactic anthropology" to detect not only the existence of life on transiting exoplanets, but also the existence of environmentalism movements. By observing the planet's atmosphere over long time baselines, the destruction and recovery of a hole in an exoplanet's ozone layer may be observable. While not readily detectable for any one system with JWST, by binning together observations of hundreds of systems we can finally determine the occurrence rate of environmental movements on Earthlike planets in the galaxy, a number we term eta-Green-Earth.