This category deals with environmental sustainability on a global geographic scale. Some starting points for the topic of environmental sustainability in general: ACTIVITIES ARE SUSTAINABLE WHEN THEY: 1 Use materials in continuous cycles. 2 Use continuously reliable sources of energy. 3 Come mainly from the non-destructive use of materials (i.e. creativity, communication, coordination, appreciation, and spiritual and intellectual development.) ACTIVITIES ARE NOT SUSTAINABLE WHEN THEY: 4 Require continual inputs of non-renewable resources. 5 Use renewable resources faster than their rate of renewal. 6 Cause cumulative degradation of the environment. 7 Require resources in quantities that undermine other people's well-being. 8 Lead to the extinction of other life forms.