Science provides the data, the hypotheses, the models and the predictions that led to the Stern review and Stern indeed commissioned some of these (see 1st link right). In the context of this site, the focus is on carbon derived energy and its production and use both by nature itself and through human activity. There are some excellent resources supporting this section hence the significant number of links provided.
For practical purposes, the law of conservation of mass states that matter cannot be created or destroyed; it can only be redistributed. Similarly the law of conservation of energy states that energy cannot be created or destroyed, it can only be converted from one form to another(s) e.g heat, light, sound etc.
With advances during the last century, particularly space exploration, we can now view the earth as an holistic system with four interacting components (atmosphere, biosphere, geosphere, and hydrosphere). The interactions between these components account for the matter and energy flows in the system, given the conservation laws. Key natural processes lie behind these interactions and in terms of carbon include photosynthesis, respiration, sedimentation, combustion, decomposition etc. Human activity adds through the processes of de- and re-forestation and other changes in land use, and in particular by many forms of combustion.
There are several reasons why a focus on carbon is so significant. Life on earth is predominantly carbon based and many of the processes above involve carbon dioxide and methane. Carbon dioxide is the major (>80%) component of the so called greenhouse gases (followed by methane). These are both very NATURAL but human activity alters their concentrations and through the greenhouse effect (follow link for animation) changes the balance between absorbed and re-radiated energy e.g. causing global warming.
supporting commissioned research
Laws of conservation of energy and matter
Earth system science components
Greenhouse effect animation
Greenhouse gas data US
Greenhouse gas data UK
Agreements to Limit Greenhouse Gas Emissions
New scientist: environment
FREE ASE 14-19 RESOURCES as of Jan 07