Matthew writes:

“My tattoo is taken from a 1950’s biology textbook. The reason it means so much to me is because of the relevence of the nitrogen cycle to the cycle of life. The horse dies, which feeds the plant, which feeds the horse. Its really quite beautiful.”Carl writes: We are each fleeting intersections of the Earth’s biogeochemical cycles, the paths of nitrogen, carbon, oxygen, and the other elements. The carbon cycle is the most familiar of those cycles today, because we are adjusting its knobs so that more carbon is shooting into the atmosphere than was the case before the Industrial Revolution, trapping heat from the sun. If we were to shut the knob off, atmospheric carbon would slowly subside