"Pete L" wrote in message
...

Yes, I know about Milankovitch - is it not a case that we are
about (+/-) a few hundred years, to go into the next downturn?
I've often wondered if man's input of CO2 is actually holding
off the next Ice Age. Would be ironic really!

The two main theories about the next glacial a

1) Mankind has already prevented it with the introduction of farming. Crops
do not drawdown the CO2 that forests do and so the widespread clearing of
land for farming has kept the CO2 levels high. Moreover, the rice paddies
produce methane which is an even more powerful greenhouse gas. Thus our
influence on climate goes back thousands of years. [
http://en.wikipedia.org/wiki/William_Ruddiman ]

2) The ellipticity of the Earth is decreasing and so the next Milankovitch
cooling will not happen for about 40 thousand years anyway. [
http://www.sciencemag.org/content/297/5585/1287 ]

Recently, Berger & Loutre have proposed that the next glacial may have been
banished forever.
http://www.nature.com/news/2002/0208...s020819-9.html I am not sure
that would be ironic. It will result in a sea level rise of over 60 m (200
feet) which will flood most farmland since it is mainly situated on coastal
plains. A 6 metre sea level rise might be held back with flood defences but
not 60 m.

Cheers, Alastair.