Why is using fossil fuels considered unsustainable?

Answer 1

Notice the word "fossils " this is no mistake. After millions of years of heat and pressure the fossils became oil and other fuels that we use. Once gone they are gone because we don't have the time that it took for the death of dinosaurs to make it.

Answer 2

Using fossil fuels is considered unsustainable because they are finite resources that take millions of years to form, yet we are rapidly depleting them. Their extraction, transportation, and combustion also contribute significantly to air and water pollution, as well as greenhouse gas emissions that contribute to climate change. Transitioning to renewable energy sources would be more sustainable in the long term.