Final answer:
The best model to help a scientist determine how forests have changed over the past five years is b) satellite images. They provide up-to-date visual data that captures changes in forest cover over time, making them ideal for environmental monitoring.
Step-by-step explanation:
To determine how forests have changed over the past five years, the most suitable model for a scientist would be b) satellite images. Satellite imagery can provide comprehensive visual data over time, which enables scientists to observe and analyze changes in forest cover, including deforestation, reforestation, and natural disturbances like fires or diseases. These images allow for both large-scale and detailed analysis, making them ideal for monitoring environmental changes.
Topographic maps are indeed useful for understanding the three-dimensional layout of the Earth's surface features and can indicate changes in elevation and shape, such as after a landslide or erosion event. However, they do not offer the same dynamic temporal perspective as satellite images, which can capture changes as they happen over a set period. Similarly, globe models and cross sections of the Earth's interior do not provide detailed information on surface cover changes over time.
Therefore, when considering options that include topographic maps, globes, and cross-sectional models, satellite images stand out as the best tool for mapping and analyzing changes in forest ecosystems over a five-year period.