Climate and collapse

Historians generally dislike theories that ascribe social change to physical change. No time for a proper report but I note that Jared Diamond took a different view in his book Collapse. More recently Michael Marshall published an article in New Scientist (4 August 2012) noting that:

• The late Bronze Age collapse (ie the collapse of the Hittite empire, Mycenean Greek culture and the Egyptian New Kingdom) coincided with the start of a dry period lasting from 1200 to 850 BC. That is roughly the time of the Greek Dark Age.
• The collapse of Tang dynasty in China and the Maya in central America both occurred around 900 AD. Recent research shows that rainfall in central America in the following century was 40% down on the preceding century. There was a similar shift in China.

 These points are contested and there are always competing views. But since the likely scale of upcoming climate change is much greater than that in either of these periods it is not encouraging.