The Element of Life
Carbon is the most social of elements. It forms bonds readily, generously, in configurations so varied that an entire branch of chemistry -- organic chemistry -- is dedicated to its partnerships. Everything alive contains carbon. Everything that was once alive returns its carbon to the cycle.
This is the paradox of our era: the element that makes life possible, when released in excess, threatens the conditions for life to continue. We are, in essence, drowning in our own ingredient.