So what if CO2 was 2400 ppmv in the Mesozoic
This is a response to those who try to claim that global warming won't be so bad. The gist of their argument is that since life thrived in the Mesozoic when CO 2 was ~2400 ppmv and temperatures 8ºC warmer, climate change today isn't anything to be worried about. Unfortunately, this argument ignores some very basic facts about biology and physics. Here is some of what they're ignoring. 1) First, thanks to those individuals for accidentally confirming the relationship between CO 2 and global temperature, as well as modern estimates of climate sensitivity. At modern solar radiation levels and with climate sensitivity at 0.809 W/m 2 , the equilibrium climate model predicts that with CO 2 at 2400 ppmv, global temperatures would rise by 9.3ºC above pre-industrial temperatures. Factor in a weaker sun back in the Mesozoic and you get the 8ºC rise experienced from 2400 ppmv CO 2 back then ( Royer 2006 ). Got to love it when those who dismiss science scor...