Sustainability refers to the survival of the systems and processes. In general terms, sustainability can be defined as the ability of the ecosystem to remain productive and diverse for generation after generation. Hence, sustainability is related to the ecosystems and environment. It is the socio-ecological procedure, which is characterized by the quest of a common purpose and ideology. The survival of the human beings and other organisms on earth is dependent on the sustainability of the environment. Thus, the equilibrium of the ecosystems and humans is essential for sustainability (Ekins et al. 2003).
Sustainability is one of the most important criteria for the development of the specific source of environmental knowledge and the renewability or the awareness of the optimum use of resources is important for the existence of the whole ecology. The food chain system along with the impacts and affects of environmental concerns and biological resources are essential for the criteria studies highlight and focuses on the not support the stocks of the relevant of the Conserving the irreplaceable stocks of critical natural capital for the sake of future generation (UNDP 2017).
There are two ideologies of sustainability: weak sustainability and strong sustainability.
Weak sustainability refers to the concept in environmental economics that deals with the idea that ‘natural capital’ can be substituted by ‘human capital’. Nobel laureate Robert Solow and John Hartwick have worked on weak sustainability. The idea states that the manufactured capital can take place of the natural capital, as long as it can be converted to manufactured capital of equal value. Thus, it states that natural and other manufactured capitals are perfectly substitutable, and there is no fundamental difference between the welfare generated by those (Kates 2010).
Capital can be described as a factor that can produce a flow of goods and services to satisfy the human needs. It can be of four types: manufactured, human, social and natural. Manufactured capital is the tools and equipments manufactured by human beings, which helps in further production; human capital is the capacities of individuals for working; social capital is the system of networks, which coordinates the contributions of individuals, and lastly, natural capital is the environmental resources that are used in the production of goods and services (Davies 2013). The key idea of weak sustainability is the optimum allocation of the scarce natural resources to generate manufactured capital. It deals with the monetary compensation for the environmental degradation. The whole value of the total stock of capital should remain same or increased for the sake of future generation. Scientific approach is usually used for determining the thresholds of the natural capital valuations.
The issues of weak sustainability are as follows.
Monetary value can be assigned to the manufactured capital but it is extremely difficult to assign a money value to the natural capital. For example, coal is a natural capital, which is extracted by humans to produce electricity. Electricity is then used as a capital for industrial and residential purpose to produce more goods as well as to improve the quality of domestic life. Hence, electricity is a manufactured capital and has a monetary value, while coal is natural capital whose value is difficult to assign (Howes et al. 2010).
Another issue in the concept of weak sustainability is that, it does not consider the fact that some natural capital cannot be substituted by manufactured or human capital. For example, the ozone layer, an ocean fishery, or a river full of salmon cannot be replaced by any human or manufactured capital (Oxley et al. 2014).
In weak sustainability, the emphasis is on economic gains rather than on the ecological scale. It does not take into account that the natural capital should be passed on to the future generation in its original form. It focuses on the idea that human can use up the natural capital and degrade the environment as long as they can compensate the loss of natural capital with the human or manufactured capital i.e. skills, knowledge, technology, machineries, infrastructure etc. However, there should be limits to the level of replacement of the natural capital, which would keep the stock in its original form for the future generation (Bond and Morrison-Saunders 2013).
These issues give rise to the idea of strong sustainability, which states that the natural capital is complementary to the human and manufactured capital.
Complementarity is central to the concept of strong sustainability, which defines that in order to survive the raw materials for a longer period the available resources must be utilized in a sustainable way. The viability of the natural resources or the goods has a limited stock unlike weak sustainability, which depends on the technical abilities to produce new means of the resources. The context of strong sustainability refers to the best utilization of the resources with a coherent cooperation between the natural and human resources. Strong sustainability resolves on the fact that it is not sufficient to last if misused but the on the other hand weak sustainability solves the environmental issues in a mechanized manner (Martins 2016).
Strong sustainability allows the optimum yet sufficient use of the resources provided by the nature to the humankind with an ideology that the services, which the capital provides, are non-renewable. It also resolves the key issues like presence of the rainforest and several natural properties like the water bodies, which has strong impacts while the ecosystem is prey to some sort of natural calamity like floods, mudslides, volcanoes etc. In fact, if there are less deforestation and less consumption of all the vacant lands eventually it affects the well being of the individual as well as the environment and eventually safeguards the social structures. The importance and significance of the natural resources help in associating with the sustainability programs for the future. As defined in the proposal of the United Nations Development Program, “Today’s generation cannot ask future generations to breathe polluted air in exchange for a greater capacity to produce goods and services. That would restrict the freedom of future generations to choose clean air over more goods and services” (Ekins 2014).
Strong sustainability do not support the replacement due to the importance of the available resources which is significant and necessary for the survival of the human kind but simultaneously weak sustainability cannot be achieved with the combined effort of the stocks and the human resources. The services, which are offered by the manufactured goods as well as the natural goods, can be contrasted to the point that one serves with a great quality and productivity but on the other hand, this is necessary for the importance of the survival of the humankind, which has social relevancy to the users of the services, human beings. Often it is necessary to take care of the non renewable source of energy like the oil and gas, minerals, sunshine etc which are called as the critical resources that cannot be produced or recreated of the sake of increased consumption (Agyeman 2008).
The comparison is necessary to comprehend the issues that are resolved by the specific set of ecological and environmental values that must be assigned to the social beings so that it can avoid the risks that are involved in the degradation process of the ecosystem. Weak sustainability aims for a multidimensional approach but strong sustainability does not follow the patterns of this approach as it is of the value that the natural source must be infiltrated and have a specific set of items that are attached to the scenario of the ecosystem.
In the concept of weak sustainability, there are certain hitches about the difference between manufactured and natural capital, which justify the concept of strong sustainability more. Strong sustainability refers to the “arrangement consisting of developing biotic and a-biotic rudiments that cooperate in ways which establish the capacity of the ecosystems in an extensive manner.” Manufactured or produced capital and natural capital are particularly two different issues that are responsible for the concept and comparison of the weak and strong sustainability (Ziegler and Ott 2015).
Firstly, these two types of capital consist of a qualitative difference. While manufactured capital can be reproduced and the destruction is not irreversible, the natural capital stock is irreversible. Moreover, the effects of the destruction of natural capital on the human beings are not well defined. Hence, implementing a precautionary rule regarding the usage of natural capital is essential (Dale and Beyeler 2001).
Secondly, the creation of manufactured capital requires the natural capital; hence, these two cannot be perfectly substitutable. Furthermore, the contributions of natural capital on the well-being of the humans are multidimensional. The strong sustainability concept focuses on the role of natural capital is central to the services provided by the ecosystem. This concept is a key point in the determination of the freedom of choice and action for the human beings. Hence, natural capital is seen as complementary to manufactured or human capital rather than being a substitute (Kates 2010).
Thirdly, the loss in the stock of natural capital cannot be filled up as quickly as the rate of increase in the demand for the future consumption. The production of goods and services in the current generation by using the natural capital can decrease the stock for future generation. That reduces the freedom of choice for the future generation. Hence, conservation of natural capital is extremely essential for the sake of intergenerational justice issue (Agyeman 2008).
Strong sustainability does not support the efficiency and collaboration of manmade and natural resources, but weak sustainability hardly disagrees on the combined effort of the two sources. The substitution of the resources is not allowed in the case of the strong sustainability, which on the other hand can be essentially utilized for the weak sustainability. The factors like critical natural capital along and ecological modernization aids in determining the aspects of strong and weak sustainability from a comparative viewpoint (Steffen and Smith 2013).
Thus, strong sustainability holds the concept of unique contribution of the natural capital in the well-being of human beings, which makes the natural capital complementary to human or manufactured capital rather than being a substitute of that. Sustainability is one of the most important criteria for the development of the specific source of environmental knowledge and the renewability or the awareness of the optimum use of resources is important for the existence of the whole ecology. Conserving the irreplaceable stocks of critical natural capital for the sake of future generation is extremely significant.
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