Without denying this function we nevertheless would rather see them as milestones on the way to a complete Local Agenda 21 process to get the most out of it for a sustainable future of your local community. The essential starting point of a Local Agenda 21, therefore, is to define the problem, i.e. to have a general understanding of what is meant by sustainability and what it is that a local community should be working towards. Even though many of them basically mean the same, there are various definitions of sustainability. According to the Aalborg Charter the idea of sustainable development is based on the carrying capacity of nature as the limiting factor. Accordingly social justice will necessarily have to be based on economic sustainability and equity, which both require environmental sustainability.
Environmental sustainability means maintaining the natural capital.
It demands from us that the rate at which we consume renewable material, water and energy resources does not exceed the rate at which the natural systems can replenish them, and that the rate at which we consume non-renewable resources does not exceed the rate at which sustainable renewable resources are replaced. Environmental sustainability also means that the rate of emitted pollutants does not exceed the capacity of the air, water, and soil to absorb and process them. It is also recognised that sustainability is a process which needs a continuous effort and affects all decisions that have to be made in local policy. It provides ongoing feedback in the management of the town or city on which activities are driving the urban ecosystem towards balance and which are driving it away. By building the management of a city around the information collected through such a process, the city is understood to work as an organic whole and the effects of all significant activities are made manifest.