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.Comment: 4 pages, 2 figures, Comments Welcom