However, were it not for certain trace gases in the atmosphere, the earth would be a frigid icy white, and life as we know it would not exist.

Our dependable local star radiates energy in all directions, a bit of which1 falls on our own planet. As it turns and wobbles and wanders through an unimaginably chilly universe, the earth soaks in solar warmth.2 Billions of years of this cosmic rotisserie nurtured an enormous diversity of living forms and processes that, through photosynthesis and respiration, helped create an atmosphere. It is that band of gases that keeps life as we know it pleasantly warm.