Bill Rees and Mathis Wackemagel created this concept to measure the sustainability of human lifestyles. It translates human consumption of renewable natural resources into hectares of average biologically productive land. Humanity, the WWF laments, is now 'running an ecological deficit with the Earth'. Sources: Wackemagel and Rees (1996); WWF (2002).
Burbules, N. C. & Torres, C.A. (Eds.). (2000). Globalization and Education: Critical Perspectives, Routledge, New York, p. 18
Choudhary, Kamal, "Buddhism and Environmental Activism", IJPS ( 1993), New Delhi, Vol.XXXIX, No. 8, July-September, Indian Political Science Association, Meerut, p.582
Held, D, McGrew, A,Goldblatt, D. and Perraton, J., (1999) Global Transformations; Politics, Economics and Culture, Stanford University Press, California, pp.75-83 .