Mathis Wackernagel and William Rees (1996), developers of the ecological footprint environmental indicator, calculated that if everyone consumed like North Americans, we would need the equivalent of three planet Earths. Germanys prestigious Wuppertal Institute calculated that global sustainability would require a 90 percent or Factor 10reduction of materials use in the developed countries (Schmidt-Bleek, 1994). This would be the minimal level needed to stabilize climate, maintain an acceptable level