The Great Acceleration is real and provides a quantitative basis for the proposed Anthropocene Series/Epoch

Abstract

The Anthropocene was conceptualized in 2000 to reflect the extensive impact of human activities on our planet, and subsequent detailed analyses have revealed a substantial Earth System response to these impacts beginning in the mid-20 th century. Key to this understanding was the discovery of a sharp upturn in a multitude of global socio-economic indicators and Earth System trends at that time; a phenomenon termed the 'Great Acceleration'. It coincides with massive increases in global human-consumed energy and shows the Earth System now on a trajectory far exceeding the earlier variability of the Holocene Epoch, and in some respects the entire Quaternary Period. The evaluation of geological signals similarly shows the mid-20 th century as representing the most appropriate inception for the Anthropocene. A recent mathematical analysis has nonetheless challenged the significance of the original Great Acceleration data. We examine this analytical approach and reiterate the robustness of the original data in supporting the Great Acceleration, while emphasizing that intervals of rapid growth are inevitably time-limited, as recognised at the outset. Moreover, the exceptional magnitude of this growth remains undeniable, reaffirming the centrality of the Great Acceleration in justifying a formal chronostratigraphic Anthropocene at the rank of series/epoch.

The Anthropocene as an Event, not an Epoch

“…Zalasiewicz et al, 2015;Syvitski et al, 2020; Figure 1). Since then, the AWG has been working towards a definition of the Anthropocene as a new series/epoch beginning around CE 1950 (Zalasiewicz et al, 2017(Zalasiewicz et al, , 2019, and appears to have reached an internal agreement that this is marked by the Great Acceleration (Head et al, 2021a).…”

The Anthropocene is a prospective epoch/series, not a geological event

“…These geological signals are supported by a large body of observational evidence that human actions from the mid-20 th century onwards have propelled the Earth System rapidly beyond Holocene conditions to a yet-to-be-determined future state. Human-driven changes to the Earth System are already profound in terms of their rates (IPBES, 2019;IPCC, 2021) and magnitudes (Waters et al, 2016;Head et al, 2021). Direct human perturbation of the biosphere and emissions of greenhouse gases are driving: a rapid decline in biodiversity and ecosystem function, together with the irreversible homogenization of biological communities; an increasing rate of species extinctions since the beginning of the 20 th century (Ceballos et al, 2015); a dramatic decline in vertebrate populations and increased rates of extinctions since the middle of the 20 th century (Ceballos et al, 2017(Ceballos et al, , 2020WWF, 2020); rapidly increasing global atmospheric surface temperatures; changes in atmospheric circulation and precipitation patterns; warming of the upper ocean, rising sea level and coastal erosion; acidification of the oceans; an increasing severity of extreme weather events such as heatwaves, tropical cyclones, wildfires, and intense rainfall and flooding; and the melting of polar ice sheets, sea ice, glaciers, and permafrost.…”

“…To test this concept from a geological/stratigraphic perspective and identify the timing of the global reach required for chronostratigraphy, the Anthropocene Working Group (AWG) was inaugurated in 2009 by the Subcommission on Quaternary Stratigraphy (SQS), itself a constituent body of the International Commission on Stratigraphy (ICS). Meanwhile, in 2004, the Earth System science community described a major upturn in the rate and magnitude of numerous global socio-economic indicators and Earth System trends occurring in the mid-20 th century, termed the Great Acceleration (Steffen et al, 2004(Steffen et al, , 2007(Steffen et al, , 2015Head et al, 2021). Many of the Great Acceleration drivers have already produced clear and widespread signatures in geological records and many other natural archives.…”

“…The abundant and growing evidence that Great Acceleration stratigraphic signals support formal definition of an Anthropocene epoch/ series has been set out in a series of publications (Waters et al, 2016;Zalasiewicz et al, 2017Zalasiewicz et al, , 2019Zalasiewicz et al, , 2020Syvitski et al, 2020;Head et al, 2021). Critical examination of this evidence by the AWG led to a nonbinding vote in 2016 indicating preference for a chronostratigraphically defined Anthropocene (Zalasiewicz et al, 2017).…”

“…An AWG binding vote in 2019 affirmed by supermajority that the Anthropocene should be a formal chronostratigraphic/geochronologic unit within the International Geological Time Scale (GTS), with a base aligned with stratigraphic signals dating to the mid-20 th century (AWG, 2019). The overall process of working towards a definition now advances with active research on 12 reference sections of which many will be proposed as candidate Global boundary Stratotype Sections and Points (GSSPs) (Waters et al, 2018;Head et al, 2021). This characterization of the Anthropocene aligns the Earth System science definition with chronostratigraphic conceptualizations of the term.…”