We are using up non-renewable natural resources, such as fossil fuels, much faster than we are finding alternatives for them.

In some respects, the natural world is already central to our concerns as renewable and non-renewable resources are depleted, ecosystems are degraded and the climate's stability is threatened.

Traditional energy resources, such as coal, oil and natural gas are non-renewable, which means that the world will eventually run out of them, constituting the main threat to energy resources.