looking at the periods prior to the modern era, for example the Phanerozoic (the term is Greek for visible life) period that occurred 600 million years prior to the present era, CO2 levels 18 times higher than the present era are found but unfortunately this was the greatest period of the expansion of life on earth. If this period were compressed into a single year, fish would have appeared in January, land animals in March, dinosaurs in June, monkeys in December and humans late on New Year's Eve. However, Phanerozoic data showing CO2 levels many times higher than today's and yet life flourished, is too embarrassing and irreconcilable with public alarms of the Global Warming advocates. "People come to me and say, ‘Stop talking like this, you're hurting the cause,' " said Dr. Giegengack, a Phanerozoic expert of Penn State University. Figure 1: The Phanerozoic Period of Earths History Figure 2: Explosion in Biodiversity during the Phanerozoic To put this into a graphical context Figure 1 shows the combined Temperature and CO2 levels for the whole of the Phanerozoic Period of 600 million years prior to the present era. To believe as Dr Jim Hansen does that 385 ppm of CO2 represents a tipping point towards the extinction of life on earth shows nothing more than his ignorance of the entire history of the earth. What it does show is the complete absence of a correlation between CO2 and temperature. No wonder the ecohondriacs find this history embarrassing. Figure 2 shows the explosion of bio-diversity at the end of the period. It is interesting that fish evolved during the Cambrian period since the oceans would have been more acidic than at today's levels of CO2. But then our green friends insist that CO2 will soon poison the oceans to such an extent that nothing will be able to survive. http://www.marxist.com/global-warming-socialist-perspective-part-one.htm