If the "permafrost" melts, it will release an immense amount of methane that has been trapped there for eons. It is already starting to do this. There are lakes in Siberia, and methane is bubbling out. Lakes in Siberia...
I think that methane breaks down in a relatively short time, though? So, in the short term, a lot of extra methane will be a very strong amplifying factor, adding to the other amplifying factors.
We are not in a long term, world wide cooling trend. The overall centuries long trend is warmer at an accelerating rate.
When the carbon dioxide was at ~1,000PPM, yes life thrived. But it took millions of years to get up to that level, and it took millions of years for it to drop again -- plenty of time for evolution to stay in step with the different climate.
And the ocean level was at least 200 FEET higher than it is now. Think about it...
Latest weather events that are outside of the norm (i.e. changed from what they were):
Australia Suffers Through More Rain : NPR
Video of flooding is here:
http://www.bbc.co.uk/news/world-asia-pacific-12162505
They've had drought for decades, and now have enormous floods ... hmmm.