All life interacts with its environment and no human activity has a truly zero effect. To advocate zero impact is to deny human existence and it is unreasonable to expect the minimum impact decision to be taken whenever there is a choice. This limits the overall environmental impact we should allow ourselves. As with monetary budgets it still gives individuals some freedom in how it is spent. At extreme ends of the scale it is usually obvious which activities are ecologically reasonable.
Most real activities fall between the extremes.
Eventually, economic activity should be governed by realistic environmental costs built into the prices of all goods and services. Meanwhile we should encourage decisions to be based on ecological as well as monetary considerations. This can only be done effectively if we have quantitative guidelines on the comparative environmental impact of different goods and services. Diversity Retaining diversity should be seen as a duty. Not only is this diversity part of our heritage, it is also vital to the sustainability of life and the ability to respond to environmental changes including those not of our making.