In our decade five main elements such as population, food manufactured industrialization, pollution- especially green house gases- and consumption of non renewable natural resources are increasing annually. Exponential growth is the name of the pattern which shows the amount of increasing every year. In general, there are two different types of graph to show the increasing, linear and exponential. When graphs show the rate (positive or negative) base on the fixed rate we name it linear graph and when the elements which are involved on the graph doesn’t move with fixed speed we name it exponential. For instance the process of the birth is exponential. Each cell divide to two cells and these two cells again divide to another two cells and finally after the specified period of time amount get doubled or tripled. From two to four, four to sixteen, sixteen to thirty two and… In exponential increasing the object rise much faster than linear. Indeed, exponential growth is an ordinary progression in nature and many other systems in the planet.
In the exponential growth when one option gets changed over time like financial matters the result would be predictable and easy to understand. But in complicated cases like nature topics with diverse alternatives analyses the outcome of the growth and predict the future behavior would be really hard. Some serious questions get involved with the complicated cases. For example, population causes the pollution or manufacturing? Is either one individually in charge for population or both? Is population affects more food production or lack of non renewable energy is involved with the issue? How much location and social behavior can change the result on the long term? For finding the answers to all questions above it is better to understand and analyses the whole complex system. System Dynamic is a straightforward method to understanding the dynamic behavior of complicated systems. Firs t of all we need to recognize the basic structure of the system that we are working on. Then get familiar with positive feedback loop or “vicious circle”. Feedback loop is a series of cause and effects that all exponential growing quantity is involved with. It means when any elements in the loop get changed by any other relative purposes (toward positive) feedback loop will start a chain of increasing changes and final result even increased more like exponential and when any elements goes in the direction of the negative feedback loop the result will decrease.
In general positive feedback loop is a good option when we want to begin our dynamic analyses of the long -term world condition. In the dynamic behavior of population growth, positive feedback loop that accounts for the observed exponential growth. In larger population -with steady standard fertility- because more people are involved, more babies will be born annually and more babies will show more population on each year graph. After some times to allow those babies to become adult and have their babies as a result more babies will born again and population will grow more and more. Steady growth will keep going as long as standard fertility stays stable with same condition. But some alternative like location, diet habits, and exercises can change the result.
In different areas, average genders of the babies are dissimilar. For example, if each woman has two or more female children in their households and each of them become adult and have more than two female children in the period of time the population will be double or more in the following generation. On the other hand the negative feedback loop is controlling the population. Negative feedback loop is based on the number of death each year and the mortality in each year depends on the several alternatives such as health of the community, natural disaster like earthquake, tornado, flood and war between countries.
There is an unbreakable chain between the positive and negative feedback loop. More birth in the community results rising the average population and because of more people in the world we have more death on the community. Also, more death leaves fewer people and less birth for the next generation. If there is no death which is impossible cause positive feedback loop of birth rise exponentially. If this case is an impossible case so what is the reason that the world population grows exponential? Is it because of the industrial revolution that changed the balance of the birth and death?
Three decade ago the life time average was just 30 years old. 30% of the children under five couldn’t survive from the child diseases. 40% of pregnant women delivered a death baby or they were died in the process of delivery. But now because of the modern medicine, public health methods and cleaner water and distribute food death rates especially in modern countries decreasing around the world.
Although the food, resources, clean water and healthy neighboring are the big factor for growth the social problems, culture in different areas and location play a big role in controlling the birth and death. For instance, in some countries like India, Zambia, Pakistan and Colombia the death of the small children is still on the board. Clean water and natural food is a problem that they are dealing week every day.
Another problem is faster than human population world economic is growing exponential. The regular growth range was 7 percent around forty years ago and the reason is the increasing amount of industrial capital including factories, trucks, machines and different tools. By calculation and consider that 7 percent economic is growing and 2 percent population growing that main positive feedback loop are increasing terrifying.
The big question is what we need to sustain world economic rate and population growth. We can list our answer into two categories. First, the physical requirements that maintains all physiological and manufacturing activities like, water, food, fossil fuel, unprocessed material, nuclear fuel and ecological system which absorb waste and recycle materials. The second category is social requirements. Social requirements factor includes education, social life, employment and technological process.