This article presents two different approaches for the study of the role of carbon as a fundamental resource for life on Earth. The article is composed of two parts, the first devoted to the description of global warming potential (GWP), a conventional standard index introduced in the early 1990s. It is acknowledged by the Intergovernmental Panel on Climate Change (IPCC) as a useful tool for evaluating the role of greenhouse gases and their changes in concentration induced in the context of greenhouse effect and climate change. GWP is also applied worldwide in the framework of emission mitigation policies of the 1997 Kyoto Protocol. The second part of this article is devoted to physiological carbon balance from an atmospheric, oceanic, land biotic, marine biotic, and mineral point of view. The carbon cycle is also affected by anthropogenic emissions that play a crucial role in the net carbon balance. This role can be accounted by the IPCC Greenhouse Gas Inventory, which is briefly mentioned. © 2008 Elsevier B.V. All rights reserved.