When I was a young child, a little friend asked me to care for her terrarium while the family went on vacation. It housed a small pet lizard to which I was to give water and food. I put the glass box on a sunny shelf in my clubhouse and promptly forgot about it. Some days later, to my horror, I found the desiccated tiny corpse. This was my first lesson about irreversible loss—in this case the extinction of a life—for which there is no remedy, no second chance, no appeal. It was also my first lesson in moral responsibility, for there was no retracing steps to do undo my neglect, no way to go back or to deny my guilt.

Humanity is now in that position, of a young child glimpsing beforehand the possibility of catastrophic change and irreversible damage through sheer neglect, with utter moral responsibility. In this case, it is not about a single creature but the fate of a planet. Now we find ourselves in the terrarium, desiccating.

On the local scale of daily life, we are used to continuity and gradual change that is potentially reversible. If something gets out of kilter, there is often something we can do about it. We feel empowered by technological success. This gives a dubious sense of confidence, especially in regard to threats posed by technology itself, or concerning the little understood delicate balances that render a biosphere possible in a hostile universe. By definition, there is no way back from a tipping point that leads to our extinction. There can be a “too late.” While the biosphere is astonishingly resilient, our sister planets Venus and Mars may be examples of things gone wrong.

Next in consequence to final catastrophe is the end of any interesting future. Life and society might survive, yet not as we currently value them. Our daily way of life and all the things we take for granted bear the seeds of collapse. For the first time, we have become an existential threat to ourselves. There are myriad fronts on which ours may be the generation that seals the fate of humanity. God will not save us and we cannot expect a fairy-tale ending. Salvation must come from us, through sober and deliberate intent now.

I learned another key lesson in childhood. My cub scout troupe held a tournament of physical contests. I signed up for arm-wrestling, for which I had no prior experience. I was shocked and embarrassed to find myself quickly defeated. Too late I realized I had no idea of the level of effort required, the force or preparation required to win—how hard to try, let alone how. Humanity is now in a similar position: we have little prior experience facing the present challenges. Only within recorded history have we even conceived such a thing as global warming or planetary demise. We can learn from the rise and fall of civilizations. But we are understandably naïve about how much effort, or what kind, is required to prevail in the long term as a species. Even as private industrialists plan to evacuate the planet, governments spend little on the long term. Fortunately, there are people and groups who at least think about the long-term future of humanity. If we survive the short term, it is even foreseeable that the long term will become a burgeoning field of study and practice—a career opportunity for young people now to consider.