ABSTRACT
When speaking about mitigation and adaptation it is important to bear in mind the elements of scientific evidence that can show us important areas of our scientific ignorance. In my opinion, there is an interesting point that this debate has tended to neglect; that is, the close relationship between greenhouse gas (GHG) emissions, concentrations in the atmosphere, temperature increase, and consequent environmental damage. It is well known what emissions and GHG concentrations are, in the sense that it is a relatively simple issue: gases are released when fossil fuels are burned. Nevertheless, the climate system reacts to GHG concentrations in the atmosphere but not to emissions. Indeed, this triggers the first problem; we switch from emissions to GHG concentrations. Of course there are some models we can use, and we somehow know there is a relationship between emissions and GHG concentrations. Greenhouse gas concentrations, for which there is well-known data, are increasing impressively (figure 1). These data on GHG concentrations are based on snow probes; this is how we know about past emissions.
