An inconvenient truth

I have always thought that even if we are wrong about the effect man has on global warming, what we do to fix it is only going to help the environment. But now I wonder. Big business has got hold of trading in emissions and taxing a country to it's knees is only acceptable if it makes a blind bit of difference.
A few figures from Air Con - The inconvenient truth about global warming by Ian Wishart
CO2 levels now - 385ppm(parts per million) - average temp 14 degrees
Co2 levels around 180 million years ago rocketed up from 1200ppm to 2500ppm and the temp dropped from 22 degrees average to 16 degrees with no cars, planes and coal fired power stations.
Are we being conceited in thinking our 3.4% of carbon emissions as compared to natures 96.6% are tipping the balance or is it just a natural, cyclic change which has happened many times before and we can do nothing about.