The current epoch of Earth’s history when humankind has joined with the other environmental forces in shaping the planet (Crutzen, (2002) Nature 415: 23; Crutzen and Stoermer (2000) Global Change Newsletter 41: 17). When did such an epoch commence? Crutzen places great weight on atmospheric composition and assumes the origin of Anthropocene to be synchronized with the appearance of the steam engine in the late-eighteenth century, which prompted a significant upturn in the burning of fossil fuels, as shown by the composition of the air trapped in the polar ice sheets and ice caps, corresponding to a sharp increase in carbon dioxide and methane concentrations in the atmosphere. However, Certini and Scalenghe (2011) Holocene 21, 1269, propose that the Anthropocene be defined as the last 2000 years of the late Holocene and characterized on the basis of anthropogenic soils.

During this era humankind has: increased its population tenfold; exhausted 40% of the known oil reserves; contributed to a 30% increase in atmospheric CO₂; transformed nearly 50% of the land surface (with significant consequences for biodiversity, nutrient cycling, soil structure, soil biology, and climate); dramatically altered coastal and marine habitats (50% of mangroves have been removed and wetlands have shrunk by one-half); and increased extinction rates (Sanderson et al. (2002) Bioscience 52, 10). The entire issue of the Holocene, 2011, 21, is devoted to early Anthropocene levels of CO₂ and CH₄.

The early anthropogenic hypothesis suggests that increased human agricultural production altered the natural interglacial trends in CO₂ and CH₄ during the latter part of the Holocene (Ruddiman, 2003, Climatic Change 6, 261).