Defining the Anthropocene

Journal name:
Nature
Volume:
519,
Pages:
171–180
Date published:
DOI:
doi:10.1038/nature14258
Received
Accepted
Published online

Time is divided by geologists according to marked shifts in Earth’s state. Recent global environmental changes suggest that Earth may have entered a new human-dominated geological epoch, the Anthropocene. Here we review the historical genesis of the idea and assess anthropogenic signatures in the geological record against the formal requirements for the recognition of a new epoch. The evidence suggests that of the various proposed dates two do appear to conform to the criteria to mark the beginning of the Anthropocene: 1610 and 1964. The formal establishment of an Anthropocene Epoch would mark a fundamental change in the relationship between humans and the Earth system.

At a glance

Figures

  1. Comparison of the current Geologic Time Scale (GTS2012), with two alternatives.
    Figure 1: Comparison of the current Geologic Time Scale10 (GTS2012), with two alternatives.

    a, GTS2012, with boundaries marked in millions of years (ref. 10). b, c, The alternatives include a defined Anthropocene Epoch following either the Holocene (b) or directly following the Pleistocene (c). Defining the Anthropocene as an epoch requires a decision as to whether the Holocene is as distinct as the Anthropocene and Pleistocene; retaining it or not distinguishes between b and c. The question mark represents the current debate over the start of the Anthropocene, assuming it is formally accepted as an epoch (see Box 1, Fig. 2). Colour coding is used according to the Commission for the Geological Map of the World10, except for the Anthropocene.

  2. Defining the beginning of the Anthropocene.
    Figure 2: Defining the beginning of the Anthropocene.

    a, Current GTS2012 GSSP boundary between the Pleistocene and Holocene38 (dashed line), with global temperature anomalies (relative to the early Holocene average over the period 11,500 bp to 6,500 bp)112 (blue), and atmospheric carbon dioxide composite113 on the AICC2012 timescale114 (red). b, Early Anthropogenic Hypothesis GSSP suggested boundary (dashed line), which posits that early extensive farming impacts caused global environmental changes, defined here by the inflection and lowest level of atmospheric methane (in parts per billion, p.p.b.) from the GRIP ice core59 (green), with global temperature anomalies (relative to the average over the period 1961 to 1990)115 (blue), and atmospheric carbon dioxide113 (red). c, Orbis GSSP suggested boundary (dashed line), representing the collision of the Old and New World peoples and homogenization of once distinct biotas, and defined by the pronounced dip in atmospheric carbon dioxide (dashed line) from the Law Dome ice core75, 76 (blue), with global temperature data anomalies (relative to the average over the period 1961 to 1990)115 (red). d, Bomb GSSP suggested boundary (dashed line), characterized by the peak in atmospheric radiocarbon from annual tree-rings (black)103 (the Δ14C value is the relative difference between the absolute international standard (base year 1950) and sample activity corrected for the time of collection and δ13C), with atmospheric carbon dioxide from Mauna Loa, Hawaii, post-1958116, and ice core records pre-195875, 76 (red), and global temperature anomalies (relative to the average over the period 1961 to 1990)116 (blue).

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Affiliations

  1. Department of Geography, University College London, Gower Street, London, WC1E 6BT, UK

    • Simon L. Lewis &
    • Mark A. Maslin
  2. School of Geography, University of Leeds, Leeds, LS2 9JT, UK

    • Simon L. Lewis

Contributions

S.L.L. and M.A.M. conceived the paper structure. S.L.L. conceived and developed the Obris hypothesis. S.L.L. wrote the geological importance, historical, farming and Orbis evidence reviews. M.A.M. wrote the Pleistocene, and industrialization and Great Acceleration evidence reviews. M.A.M. conceived and developed the figures. The final two sections, written by S.L.L., emerged from discussions between S.L.L. and M.A.M.

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  1. Report this comment #65481

    Simon Pooley said:

    In this fascinating article ?Defining the Anthropocene,? Lewis and Maslin propose that ?the arrival of Europeans in the America led to a catastrophic decline in human numbers? (2015: 176) which resulted in extensive agricultural abandonment and a resulting increase in forest from 1550-60, resulting in the 1610 decrease in atmospheric CO2 they use as a GSSP to mark the onset of the Anthropocene.

    I wonder whether and how the authors have compared this return to forest ? assuming these lands were not maintained as open vegetation by natural fires, or colonised by introduced weedy plants ? with deforestation in Europe and elsewhere. In Deforesting the Earth (2006), Michael Williams recounts that ?the attack on the European forests was renewed with vigour as population rose ? from approximately 82 million in 1500 to 105 million in 1600? (151). Local shortages were widely recorded across what are now Britain, Netherlands, France and Germany. Grain fields were carved out of the forests of the Baltic and in southern Europe, extensive migratory livestock grazing stripped the hills of forest. Forests were furthermore in retreat in response to shorter growing seasons during the Little Ice Age.

    In South America, trees were cleared for plantations, and firewood to boil cane syrup, and cattle ranches were established to provide meat and oxen for carting, and much the same happened on Atlantic and Caribbean islands. The introduction of new food crops from America into West Africa resulted in a fifteenth-century ?big bang? in the forests, with cassava and maize planting at the forefront of a ?human assault on the forest landscape (McCann 1999: 119).

    If we are to accept a causal link rather than a correlation between a population crash in the Americas causing reforestation of abandoned farmlands, and a GSSP marker linked to a strong climate signal, we probably also need more historical research. We need to retrieve as detailed a regional and global a picture as we can of anthropogenic impacts on forests in the period 1550-1650.

    Dr Simon Pooley
    Imperial College Conservation Science
    s.pooley@imperial.ac.uk

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