> Carbon Dioxide content is very small, invisible on a bar chart. Anyone raising the point that "CO2 is only a tiny fraction of the atmosphere" immediately mak

> Carbon Dioxide content is very small, invisible on a bar chart. Anyone raising the point that "CO2 is only a tiny fraction of the atmosphere" immediately makes me suspicious. The implication, I guess, is that because it is a tiny fraction of the atmosphere, CO2 can't possibly be that important. But of course every plant, every animal, and every person you know is made out of carbon that was very recently atmospheric CO2. So it's at least a little important. And if someone is .0001% ricin, they are dead. A few parts per billion turn a crystal of silicon into a semiconductor. A dosage of 0.05% chromium turns a crystal of aluminum oxide into a ruby. So even small chemical changes can have a big effect.