From good guy toblack hat

摘要

Once upon a time, carbon was a good guy - the stuff of life. I first learned about it at high school, where the school emblem was a hand cradling a carbon atom. These days, carbon more often wears a black hat - it is a pollutant and the agent of climate change (said to be the most important global environmental crisis mankind has ever faced). Some years ago, I attended a lecture on global carbon distribution, in relation to what were then considered possible climate impacts (nothing 'possible' aboutit any more). The speaker went to great lengths to emphasise how widely the various estimates varied (at that time), but still tried to come up with some sort of realistic picture of where all the carbon in the world was found. Figure 1 is a pie chart to show (in general terms) what he came up with.