carboniferous
this
graph from this
web page is interesting. it shows global average temperatures for the past 600 million years. the first interesting thing is the scale. the classic
hockey stick is entirely contained within one pixel on the far right. the next most interesting thing is temperature and co2 don't correlate very well. maybe sometimes. if you squint. which means that the co2 folks are completely nuts. on the other hand the sun was dimmer in the deep past and has been getting warming. that's not reflected in the graph either. now it's the solar crowd that's completely nuts. heh. i'm thinking a more reasonable conclusion would be that time scales of say 10 million years are of limited value for understanding things at human time scales. though that won't keep me from trying. kinda looks like the earth has two stable temperature states: hot at 22 C, and cold at 12 C. some process appears to kick in to keep the earth from cooking or freezing. which is comforting. sorta. the upper cap is some 7 C warmer than today's global average. where i live it occasionally gets to be 105F. the cap'd put that at some 120F. toasty.