Earth's Carrying Capacity In the year 2011, Earth reached a huge milestone. The human population rose to 7 billion people. This growth seems incredible. The population was just 6 billion in 1999. This means the population increased by 1 billion people in only 12 years!
However thrilling this news may seem, it also has people worried. Many scientists doubt that the planet can support so many people. They think that Earth may be reaching its carrying capacity.
Carrying capacity is another way of saying maximum population. The idea was first introduced by Thomas Malthus in the 18th century. Carrying capacity has to do with balance. Just as a pond can only have so many fish, Earth can only have so many humans. The planet has a limited amount of air, food, and water. When these things are easy to get, the human population grows. When these things become scarce, or hard to find, Earth reaches its carrying capacity.
Sadly, there is proof that today's population levels are already harming the Earth. But it is important to remember that carrying capacity is not a fixed number. By taking better care of the planet, we might be able to support future population growth. Which of the following does the author use to support the belief that population growth could be a problem?
A. an account of the life of Thomas Malthus
B. an estimate of Earth's remaining water supply
C. a definition of the term "carrying capacity"
D. a fact about how the population has decreased