Forget that rolling stone ...

... it's the moss you have to watch out for: First land plants plunged Earth into ice age - environment - 01 February 2012 - New Scientist.

The first land plants appeared around 470 million years ago, during the Ordovician period, when life was diversifying rapidly. They were non-vascular plants, like mosses and liverworts, that didn't have deep roots.
About 35 million years later, ice sheets briefly covered much of the planetand a mass extinction ensued. Carbon dioxide levels probably fell sharplyjust before the ice arrived – but nobody knew why.