The UnAustralian

Thursday, January 08, 2004
Climate Change and Human History

I'm going to use this post to finish up my short series on William Ruddiman's groundbreaking work on early human influences on carbon dioxide and methane concentrations.

Ruddiman has put forward a interesting thesis which has the potential to explain many unexpected results from ice-core measurements. Whether or not the theory is correct, but in the eyes of this amateur, it is currently the only theory which can explain the observations. Hopefully this paper will spur more people into thinking about the issue.

It has been estimated that the presence of these extra gases should have warmed the earth by ~0.8 K. Not a small amount. However, because this warming was spread over 8000 years, and that orbital changes were introducing a cooling trend, the warming was masked. However, this does not mean that it's effects weren't noticed. Northern Canada, for example, undergoes regular glaciation. However, during this orbital cycle, the glaciers haven't come, rather, the radiative forcing of the extra greenhouses gases seems to have made the difference.

In an ironic twist, it has been argued in the past that the Little Ice Age was a contributing factor to many of the epidemics and pandemics which hit humanity hard. However, if this theory is correct, then we have to do a half-turn and conclude that the epidemics and pandemics were a contributing factor to the Little Ice Age.

It's a strange world in which we live.
| 9:38 PM