Global environmental change (GEC) is among the most severe challenges facing mankind today. It is a suite of environmental change problems, climate change being the most studied of all. Global environment includes physical, chemical, and biological processes that are necessary for life-supporting services on the earth. No studies on a single environmental component will be meaningful for GEC, if viewed in isolation. It is the feedback between various components that assumes greater importance for GEC and, hence, the term GEC involves changes in various components of the environment.