Human Population Growth Graphing Activity



Human Population Growth

Objectives:

• You will analyze a graph of human population growth and use it to predict future growth.

• You will identify factors that affect population growth.

Statistics on Human Population

Directions: Using excel, create the graph of the different populations & print it out. Then answer the questions based on the data and your graph.

|Year A.D. |# of People (in |# of People (in |# of People (in |# of People (in |# of People (in |

| |millions) in the |millions) in the |millions) in Mexico|millions) in China |millions) in Ghana |

| |World |USA | | | |

|1650 |500 |.0004 |1.5 |150.0 |N/A |

|1750 |700 |1.2 |5.6 |179.5 |N/A |

|1850 |1000 |23.2 |7.5 |429.9 |.28 |

|1925 |2000 |115.8 |15.2 |480.4 |2.5 |

|1956 |2500 |168.9 |33.9 |619.1 |6.2 |

|1966 |3300 |196.6 |46.8 |735.4 |7.9 |

|1970 |3600 |205.1 |53.0 |818.3 |8.6 |

|1974 |3900 |213.9 |59.9 |900.4 |9.6 |

|1976 |4000 |218.0 |63.5 |930.7 |10.0 |

|1980 |4400 |227.2 |70.4 |981.2 |10.8 |

|1991 |5500 |253.0 |87.9 |1150.8 |15.0 |

|2000 |6000 |282.2 |103.9 |1262.6 |18.8 |

|2004 |6400 |292.8 |109.4 |1296.1 |20.8 |

|2008 |6700 |304.1 |115.0 |1324.7 |23.1 |

|2012 |7100 |313.9 |120.8 |1350.7 |25.4 |

Analysis

1. It took 1649 years for the world population to double, going from .25 billion people to .50 billion people. How long did it take for the population to double a second time?

2. How long did it take for the population to double a third time? ___________

A fourth time? ________________

The Earth's Carrying Capacity

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 goods. 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. At this point in our history, people believed that nothing could stop the population growth, that it would keep growing exponentially* – faster and faster as time goes on.

* A graph that keeps rising faster and faster with no limits is called exponential growth.

As with any population, humans are also limited by factors such as space, amount of food, and disease. These factors are called limiting factors; they control how large a population can grow. The carrying capacity is the number of individuals that a stable environment can support. Authorities disagree on the carrying capacity of people that the earth can support, though the numbers generally range from 8 to 10 billion. As the population approaches its limit, starvation will increase. Scientists now call our population growth logistic - because it is not logical that a population can keep growing forever without limits. We have a finite* planet, so we cannot have an infinite amount of people.

*having bounds or limits; not infinite; measurable

Some countries have a much higher growth rate than others. A growth rate is the number of people born minus the number of people that die. Most countries are trying to reduce their growth rate. Zero population growth means that the amount of people that are being born is the same as there are dying - to achieve zero population growth, each couple would need to have no more than 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.

1. Define the following terms.

Exponential growth-

Logistic growth-

Carrying capacity-

Limiting factors-

2. What factors contributed to the world's overall population growth in the last 150 years?

3. If the carrying capacity of the earth was 9 billion people, when would this number be reached (USE YOUR GRAPH TO ANSWER THE QUESTION)?

4. What will happen when the human population exceeds the earth's carrying capacity?

Upsetting the Ecological Balance

Many countries try to grow more food in order to feed their growing numbers of people. Each year, about 18 million acres of forests (an area equal to the size of Vermont and New Hampshire combined) are cut down to create more farmland and grazing land and to obtain wood for fuel and other uses. The loss of these forests affects the entire Earth. Consider that rainforests are home to half of the world’s animal and plant species, some of which may provide key ingredients for medical innovations. The loss of these species could devastate the delicate ecological balance.

Water supplies also suffer as the population continues to grow, especially in less developed regions that lack the ability to transport water across long distances. As more food is needed to support greater numbers of people, a larger amount of water is dedicated to agriculture. This greatly depletes water supplies and leaves less available for drinking and sanitation. Currently, almost one million people around the world lack safe drinking water and 2.6 billion people suffer from inadequate sanitation.

Loss of biodiversity is another problem associated with overpopulation. As cities expand with population growth, previously uninhabited lands, such as forests and prairies, are developed for human use. Many of the most biologically diverse regions on Earth have lost more than 70 percent of their vegetation due to human activity. As the ranges of the native species in these regions diminish, they are much more likely to become extinct.

Even the e live on is affected by overpopulation. Soil is destroyed as larger livestock herds become necessary to produce more food. Billions of animals are now over-grazing the world’s grasslands, turning them to dust. Croplands are destroyed when the rich topsoil blows away after being overworked and misused. This devastation of land has left millions of environmental refugees worldwide, as people are forced to migrate from their homes in search of more fertile land, cleaner water, and a better quality of life.

5. How is each of the following areas - sanitation, biodiversity, water, & land - affected by overpopulation? List at least two ways for each.

• Sanitation - the study and maintenance of public health and hygiene, especially the water supply and sewage systems

• Biodiversity – range of organisms in the environment

• Water

• Land

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