Both sides of the global warming debate agree that there is a close correlation, over the last 800,000 years, of CO2 concentrations in the atmosphere with global temperatures. Furthermore it is generally agreed that hitherto, the rise in temperatures preceded the rise in CO2 levels by an average of around 800 years.
Inevitably the relationships are complex and this referenced article gives a much more detailed account of the evidence: CO2: Ice Cores vs. Plant Stomata by David Middleton
However, the IPCC and the pro-global warming lobby insist that it is now CO2 which is driving the rise in temperature with no hard evidence to support this illogical premise. On the contrary, temperatures rose fairly rapidly from about 1900 to 1940 but then declined until the late 1970s during a period when CO2 emissions were rising in the post-war industrial boom. According to satellite data,
following peak temperatures in 1998 there has been no warming of statistical significance in spite of a further increase in CO2 emissions.
95% of greenhouse gas is water vapour, CO2 is a relatively minor constituent making a marginal contribution to the greenhouse system.
Studies acknowledge that rises in CO2 concentrations have a warming influence but that it is logarithmic, ie. the first 20 parts per million have the most effect but thereafter the influence wanes to negligible by the time the current 393 parts per million are reached. CO2 concentrations have been much higher in the past.
CO2 is beneficial for promoting plant growth which is important if we are to feed the growing global human population without destroying our environment. Below 150ppm nothing would grow and we'd all die. Dutch growers buy CO2 to increase concentrations in their greenhouses to increase crop yields. So it seems perverse to describe a basic building block of life on earth as a pollutant.
Finally, while acknowledging that the earth’s climate is a complex system with millions of variables, the correlation between solar activity and temperature appears much more compelling: