Human health, in the coming decades (and already in some “front-running” regions), is in peril. Although some authorities warn that over-stating such risks can induce paralysis and despair, under-stating them will not generate the intense action that is required. The impact of climate change on the Earth system is now so significant that the next ice age will likely be delayed by at least 50,000 years [201]. If humans do not rapidly change their collective behavior, then this may be their most enduring legacy. It is hoped that this chapter makes a small contribution to SDG3.