Just to get things into perspective, the current levels of atmospheric CO2 are estimated to comprise just 0.04% of the atmosphere, having risen from 0.028% since the beginning of the industrial revolution.
The average global temperature since the beginning of the industrial revolution is estimated to have risen by around 0.8 degrees centigrade. This figure can only be a very rough approximation because of the lack of accurate, modern thermometers a hundred or two hundred years ago. In order to get some idea of past temperatures scientists have to make reconstructions using proxies such as tree rings, lake sediments, ice cores, corals, and so on.
During the past century, sea levels are estimated to have risen by about 160mm, a bit over 6 inches. How fortunate we are. In the past, after the last ICE Age, sea levels rose by an average of one full metre per century, and occasionally as much as 3 or 4 metres in just one century.
There are many ongoing problems that humanity faces, such as poverty, health problems, food shortages, eternal conflicts, wars, terrorism, the destruction and loss of life due to natural events such as earthquakes, tsunamis, floods and hurricanes, and the real pollution of our planet due to the release of toxic chemicals from farming, various industrial processes, and of course out-dated fossil fuel power plants, and motor vehicle emissions.
All of these problems will continue with certainty if we don't tackle them. Directing our efforts and resources to tackling far less certain issues and problems, such as the possible adverse effects of rising CO2 levels, doesn't make sense to me.
If Bernard really believes it is 99.9% certain that man's emissions of CO2 is the dominant factor causing the current period of global warming, I think he's living in 'cloud cuckoo land'.