Geoscience Reference
In-Depth Information
Early farmers
The very high-resolution ice-core evidence from Greenland and the continental margins of
Antartica also show that GHGs in the atmosphere rose a small amount before the industrial
revolution in the 1700s. Bill Ruddiman, Professor of Palaeoclimatology at the University of
Virginia, suggested that early agriculturalists caused a reversal in natural declines of atmo-
spheric CO
2
starting about 7,000 years ago and atmospheric CH
4
starting about 5,000 years
ago. This idea has caused a huge amount of controversy, but like all good theories it has
been tested again and again, and no one has yet been able to disprove it. So essentially it
says that early human interactions with our environment increased atmospheric GHGs just
enough that even prior to the industrial revolution there was enough influence to delay the
onset of the next ice age, which would otherwise have started gently to occur anytime in
the next 1,000 years.
