Hello, I am an ordinary citizen of the world, with an interest in starting a forum for others interested in environmental stewardship. Here is what inspired me. In a book I am currently reading, "A Life on Our Planet" by David Attenborough, I ran across this graphic. Has anyone else seen this before? When I search online, I see other versions of the model too. Attenborough refers to a team of earth system scientists who have named nine different boundaries that determine whether we can continue to live sustainably on our planet. They came up with a threshold beyond which sustainability is doubtful. It may be difficult to read from the photo I have inserted here, but the nine areas are climate change, ocean acidification, chemical pollution, fertilizer use, freshwater withdrawal, land conversion, biodiversity loss, air pollution, and ozone layer depletion. The dark shading shows those of the nine that have been measured in a quantifiable way. The dark ring is the threshold. ...