"And some postulate that it was man who started changing the...

"And some postulate that it was man who started changing the climate 10,000 years ago."

No they don't. (Ignoring the fact that it was 'stable' i.e. not changing for 10,000 years.) Having said that, land clearing and agriculture does have the capacity to change the climate due to interrupting the carbon cycle, but I doubt it was significant until the industrial revolution. The numbers wouldn't stack up.