Sources and sinks: emission and absorption of greenhouse gas. A case study in Italy

The biosphere is a closed thermodynamic system: it receives an enormous flux of energy from outside while the exchange of matter with the outside is practically negligible. Life on Earth is continuously assured by this flux of energy from the Sun (source), as well as by the capacity of dissipating heat in the outer spaces (sink), as efficiently formalized by the entropic model by Harold Morowitz. This makes life possible and is the reason why large changes induced artificially by man in periods that are brief on the scale of biological time are so dangerous. For this reason it is important to develop methods able to detect how much human activity affects the natural flow of energy from the source to the sink. Nowadays one of the points of major debate in international issues is the problem of the greenhouse effect and related climate change, as well as the main cause of the problem: massive fuel consumption. This paper presents the results of a Greenhouse Gas Inventory, calculated for the complex territorial system of the province of Siena (central Italy) according to the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories. It is a method of assigning the responsibility of greenhouse gas emissions at local level and it suggests how to improve public policies in terms of resources and land use by the comparison of emissions and natural absorption of equivalent CO2. The paper also emphasizes how the diversities in terms of environmental characteristics, urban areas management and economic propensities within a territory can be a good model to follow towards sustainable development