Final answer:
The human population is currently experiencing exponential growth, indicated by the rapid increase from 1 to 7 billion people. The exponential growth contributes to concerns about resource allocation and available space. Age structure diagrams help represent different stages of population growth, including decline.
Step-by-step explanation:
The current human population is experiencing exponential growth. This pattern is characterized by a rate of growth that is not only increasing but is doing so at an accelerating rate, which is indicative of exponential growth. Notable historical milestones in human population include the fact that it took approximately 123 years for the population to increase from 1 billion to 2 billion. This rapid increase in population was much faster than the time it took to reach the first billion, which was a gradual process over millennia, suggesting an acceleration in growth rates.
Today, the current world population is around 7 billion, indicating the continuing trend of a rapidly expanding population. However, some countries do experience a negative growth rate, indicating a decrease in population size within those specific regions. Overall though, the human population growth is contributing to concerns about available space and resource allocation due to the increasing demand created by a larger population.
According to age structure diagrams, a rapidly growing population would typically be represented by a pyramid shape with a wide base, whereas a stable or slow growing population would have a more uniform distribution across age groups. The fourth stage in such diagrams usually indicates a declining population with more older individuals than younger ones.