Note the very long timeline below. The fossil fuel era is long compared with human life spans, so we apt to think that it is "normal." In the long reach of history, it is not normal.
M. King Hubbert drew a diagram like this for testimony before Congress in 1974. No one paid attention, of course, just like they paid little attention in the 1950s when he projected American peak oil in 1970. Hubbert did not seriously address "greenhouse gases."
Today there's even speculation on when China will hit "peak coal." They burn it at about twice the U.S. rate, but have about half the known reserves.
