Prior to 1950, the death rate was high, which kept the numbers of humans from increasing rapidly. In the 19th Century, the agricultural revolution increased food production. The industrial revolution improved methods of transporting food and other good. In the 20th Century, advances in medicine, sanitation and nutrition have decreased the death rates further. These factors combined to produce the rapid growth of the human population in the 20th century. As with any population, humans are also limited by factors such as space, amount of food and disease. The carrying capacity is the number of individuals that a stable environment can support. Authorities disagree on the maximum number of people that the earth can support, though the numbers generally range for 8 to 10 billion. As the population approaches its limit, starvation will increase. Some countries have a much higher growth rate than other. Growth rate is the number of people born minus the number of people that die. Compare the growth rates of the following countries. Most countries are trying to reduce their growth rate. Zero population growth means that as many people are being born as there are dying - to achieve zero population growth, each couple would need to have no more two children (to replace the parents). Even if this number is achieved, the population will continue to grow because the parents will still live on for decades, as their children have children and their children have children and so forth. The United States reached zero population growth in the 1980\'s, and yet the overall population of the US still increases. Analysis: What factors contributed to the world\'s overall population growth in the last 150 years, Why does a population not level off during the same year it reaches zero population growth? If the carrying capacity of the earth was 9 billion people, when would this number be reached (according to your graph)? What will happen when the human population exceeds the earth\'s carrying capacity?
1. The agricultural revolution led to an increase in the food production.Through industrial revolution the methods of transporting food and other goods were improved.Advances in medicine,nutrition and sanitation decreased the death rate among individuals.All these factors led to increase in the world population in the last 150 years.
2. The population does not level off once zero population growth is achieved because the parents of the children will continue to live for many more years.Once the children will become parents they will also continue to live ,so the population is not levelled even if zero population growth is observed because of the survival of the parets for many more years.
3. The carrying capacity of 9 billion people will be reached by 2030-2040.
4. When the human population exceeds the carrying capacity starvation will take place.People would fight over the limited resources,which would lead to increase in death rate.
Homework Sourse
