Final answer:
Human activity moves carbon from ancient underground fossil fuel deposits into the atmosphere by burning them, releasing CO2 and impacting the carbon cycle.
Step-by-step explanation:
Human use of fossil fuels has moved large amounts of ancient stored carbon from the Earth's geologic reservoirs, such as deep underground fossil fuel deposits, into the atmosphere. This transfer is a crucial part of the biogeochemical carbon cycle, which is a natural process where carbon is exchanged between various reservoirs on Earth.
Fossil fuels, which are the anaerobically decomposed remains of ancient organisms, represent a major carbon store that has been sequestered over millions of years and is considered a non-renewable resource due to its very slow regeneration rate. When these fossil fuels are extracted and combusted for energy, they release carbon dioxide (CO2) into the atmosphere. This CO2 is a greenhouse gas that can contribute to global warming and climate change, as it traps heat within the Earth's atmosphere.