Nate Hagens defines 'fossil fuel' as a highly concentrated form of ancient solar energy stored in decomposed organic matter, primarily plants and microscopic organisms, which over millions of years have been subjected to intense heat and pressure beneath the Earth's surface. These energy-rich substances, including coal, oil, and natural gas, serve as the foundational pillars of modern industrial society, driving economic growth and facilitating human activities on an unprecedented scale. However, Hagens emphasizes that while fossil fuels have catalyzed tremendous technological and social advancements, they also embody a finite and non-renewable resource, the extraction and combustion of which pose significant environmental and ecological threats, such as climate change and habitat destruction. Thus, Hagens highlights the paradox of fossil fuels as both enablers of human progress and catalysts of significant planetary challenges.

See also: fossil carbon, fossil hydrocarbons, fossil energy, carbon pulse