*3.1.4. Social sustainability*

sustainability: Environmental, economic, and social sustainability. In addition, within each of

The basic aim of environmental sustainability is to maintain healthy, productive, and species rich ecosystems. Such "supporting ecosystems" deliver "environmental services". They have a certain tolerance to disturbance, and a certain "carrying capacity" regarding production of goods as wildlife, fish, various forest products, clean water, fertile soil, etc. Healthy ecosystems also have a certain "assimilative capacity" for our pollution and wastes. Many prefer to use the concept of "natural capital" for nature's ability to serve us, and this capital has to be maintained. Furthermore, the term "sources" is often used for raw materials extracted from nature, and "sink" for wastes. A "sustainable production" and a "sustainable consumption" implies to live within the limitations of the biophysical environment, while "overconsump‐ tion" gradually liquidates nature's ability to deliver environmental services. Loss of nature also implies loss of other "services" like recreation, various cultural values, and nature as a

As long as nature was "in excess", nature's productivity and assimilative capacity was enormous compared to man's needs and activities. Today, healthy ecosystems have become a scarce resource, like intact forests, species-rich coral reefs, productive oceans, clean rivers, or fertile soils. During the last sixty years, ecological thinking and ecological concepts have become a cornerstone in defining the limits – but also the options – for man in a sustainable future. The conceptual development within the rise of applied ecological thinking is presented

Since economic development is one of the primary drivers behind environmental degradation, economic activity should be kept within strong limits. For instance, to eradicate one resource after the other (e.g. whales, tropical forest, oil wells and fish stocks) may be good economics in terms of income, but totally unsustainable. Environmental costs have to be included in economic activity. A "sustainable economy" can be regarded as a human economy subsystem which does not harm the ecosystems and their ecological services on which we depend. Economics has rarely been concerned with natural capital, because until recently, these resources had not been scarce. The new scarcity of natural capital arose because the *scale* of the human economic subsystem had grown large relative to its supporting ecosystem. The "scale criterion" would constrain the so-called "throughput growth" – the flow of material and energy (natural capital) from environmental sources to sinks (pollution and waste), via the human economic subsystem. However, due to our limited knowledge about nature's resilience and the danger of irreversible damage to ecosystems and their services, economists need to use the precautionary principle routinely. Also in economics, ecological thinking and concepts

these concepts, there was a need for subconcepts [6], as explained below.

*3.1.2. Environmental sustainability*

128 Environmental Change and Sustainability

source of fascinating science.

*3.1.3. Economic sustainability*

have become relevant.

in chapter 3.2.

This concept points to a peaceful and tolerant community kept together by cooperation, but also by laws and discipline. Also here, the concept of capital is used. "Human capital" is created by investment in education, health and nutrition of individuals. "Social capital" points to the importance of social stability, and "moral capital" indicates shared values and equal rights. All three types of capital are threatened by the underlying problem of unchecked population growth. There is much debate about how many people the globe can support, but too little about how far we are above a "population optimum". The Norwegian professor in social economy, Ragnar Frisch, who in 1969 received the Nobel price in economy, tried already in 1940 to define a "population optimum". He argued that because natural resources in each country are limited, there is an optimum population size which gives the best quality of life for people within a specific area of land [12]. The concept of population optimum deserves to be used in visions about a sustainable future.
