Sustainability has taken on a new meaning in the beginning of the twentyfi rst century with the realization that ours is the fi rst generation to have an impact on the whole global system. For the main part of the existence of the human species on this planet, nature was overwhelmingly large and humans just a small group living at the mercy of natural forces. Even in the year 1800, the world population was only 900 million. Most people were still living in poverty with a limited impact on the environment. New technologies and industrialization changed this radically.