Final answer:
The most important factor contributing to global declines in biodiversity is the combination of human population growth and resource exploitation.
Step-by-step explanation:
The most important factor contributing to global declines in biodiversity is the combination of human population growth and resource exploitation. As the human population continues to grow, the demand for resources increases, leading to habitat loss, overharvesting, and the introduction of exotic species. These factors directly result from human population growth and resource use. Additionally, anthropogenic climate change, which is caused by human population needs for energy and the use of fossil fuels, is predicted to become a significant cause of extinction in the future.