Which of these events is NOT a natural occurrence that can change an ecosystem?

Burning fossil fuels is considered a human-induced event rather than a natural occurrence. Unlike natural phenomena such as landslides, flooding, and wildfires—which occur as a result of environmental processes and factors—burning fossil fuels stems from human activity aimed at generating energy. This activity significantly contributes to environmental changes, such as air pollution and climate change, which in turn can lead to disruptions in ecosystems. Understanding this distinction helps clarify why the other events are naturally occurring and integral parts of ecological dynamics, while burning fossil fuels represents an anthropogenic influence on the environment.