The concept of viability envelopes (physical, chemical, biological levels) is developed as well as the general consequences and conditions to put in place a global and local sustainable development as defined by official institutions. The three logics and associated regulation processes that define a viable relation-space are presented. Some sentinel variables are proposed. There are, for example, the population life expectancy (PLE) and net photosynthetic production (NPP) on a soil or a sea of ecological quality, as well as the mean temperature and atmospheric C02 variation velocities. These elementary indicators permit us to follow and evaluate the degree of interaction between human oxygen respiration and energetic consumption with the photosynthetic oxygen production by green plants, as well as the correlation with the thermic and greenhouse effect. The increase or decrease of PLE and NPP as well as the phase-space evolution of the thermic and C02 pattern can give us a precocious information, for the near future, on the sense of sustainability (positive or negative way) provoked by a socio-economic pattern and energetic choice. A cybernetic model is presented as well as different ways of positive adaptation and management.