3:30 PM - 3:45 PM
[MIS12-05] Definition of the Anthropocene onset using a geological Great Acceleration marker: a rapid increase in anthropogenic fingerprints
Keywords:The Anthropocene, anthropogenic fingerprints, plutonium, nuclear bomb tests, The Great Acceleration
The stratigraphic signal of increase in Pu in 1952 CE is considered a primary marker for identifying the lower boundary of the Anthropocene, and it is proposed as a rationale for the isochronous boundary of the proposed Anthropocene series/epoch. However, there is a debate suggesting that the radioactive contamination from nuclear bomb tests may not necessarily be a major global forcing affecting the entire Earth system but rather only providing a synchronous signal in the strata over the globe. The question remains unanswered as to what stratigraphic signal should be used to define the lower boundary of the Anthropocene, representing a fundamental change in the Earth system caused by human activities, and what year it should be defined.
This study focuses on the Great Acceleration, an unprecedented and abrupt change in human society and earth systems observed in various social and environmental indices around 1950 CE as a turning point where humans began to force substantial changes on the Earth system. Here we propose the rapid increase in anthropogenic fingerprints in the strata as a geological expression of the Great Acceleration. In the Beppu Bay sediments, an unprecedented sharp increase in anthropogenic fingerprints is observed in 1953, considered clear evidence of the Great Acceleration in the strata (Kuwae et al. 2023, The Anthropocene Review). However, on a global scale, it has still not been explored whether the sharp increase point shows the isochronous signal suitable for setting the stratigraphic boundary.
This study constructs a dataset of chronological data on anthropogenic fingerprints identified from 263 proxy records with high-precision age determinations, reconstructed from varved sediments, ice cores, coral skeleton, and tree rings, and covering 141 locations worldwide. The dataset spans the past 5700 years and includes 748 anthropogenic fingerprints such as initial detection and rapid increase of novel materials including spheroidal carbonaceous particles, PCBs, plastics; an unprecedented increase or decrease in stable and radioactive isotope ratios, greenhouse gas concentrations, organic geochemical signatures, heavy metal concentrations and fluxes, proxies of temperature, water temperature, salinity, pH; and major changes in elemental and biological community compositions. Change point analysis of the cumulative number of anthropogenic fingerprints, using 13 subsets eliminating biases in data representation, indicates the onset of a rapid increase at 1952 ± 3 years (1 SD). However, excluding radionuclide signals, a rapid increase starts in the 1940s.
On the other hand, examining individual regions such as the Arctic, Antarctic, Europe, North America, East Asia, Oceania, and other regions, the maximum slopes of the cumulative number of anthropogenic fingerprints occurs in 1953-1957 (1955 ± 2.5 years), indicating a clear synchronicity in the timing of the maximum increasing rates in fingerprints between the regions. When excluding the radionuclide signals with simultaneity through short-time atmospheric diffusion over the globe, the maximum slopes are observed in all regions between 1949 and 1964 (1957 ± 8 years). The nearly-simultaneous explosion during this period represents a point where rapid, diverse, and intense anthropogenic modification spread out on a global scale, providing a clear rationale for the boundary that distinguishes the proposed Anthropocene from previous periods with diachronous local/regional human modification of the Earth environments. Between 1953-1957, the concentrated timing of the maximum slopes of the cumulative fingerprint number in each region, including the radionuclide data, implies that the radionuclide signal is a major factor forming the rapid increase point of anthropogenic fingerprints. However, if this signal is considered as one element constituting the overall acceleration of human disturbances against the Earth system, including diverse environmental, ecosystem, and material cycling changes, the nuclear test signal can be seen as a component of the Great Acceleration. The rapid increase in anthropogenic fingerprints, including the nuclear test signal, begins at the change point of 1952 ± 3 CE. Therefore, defining the beginning of the Anthropocene as the point when explosions of diverse anthropogenic fingerprints start spreading out globally, the age of the onset of the Anthropocene can be identified as 1952 ± 3 CE.
This study focuses on the Great Acceleration, an unprecedented and abrupt change in human society and earth systems observed in various social and environmental indices around 1950 CE as a turning point where humans began to force substantial changes on the Earth system. Here we propose the rapid increase in anthropogenic fingerprints in the strata as a geological expression of the Great Acceleration. In the Beppu Bay sediments, an unprecedented sharp increase in anthropogenic fingerprints is observed in 1953, considered clear evidence of the Great Acceleration in the strata (Kuwae et al. 2023, The Anthropocene Review). However, on a global scale, it has still not been explored whether the sharp increase point shows the isochronous signal suitable for setting the stratigraphic boundary.
This study constructs a dataset of chronological data on anthropogenic fingerprints identified from 263 proxy records with high-precision age determinations, reconstructed from varved sediments, ice cores, coral skeleton, and tree rings, and covering 141 locations worldwide. The dataset spans the past 5700 years and includes 748 anthropogenic fingerprints such as initial detection and rapid increase of novel materials including spheroidal carbonaceous particles, PCBs, plastics; an unprecedented increase or decrease in stable and radioactive isotope ratios, greenhouse gas concentrations, organic geochemical signatures, heavy metal concentrations and fluxes, proxies of temperature, water temperature, salinity, pH; and major changes in elemental and biological community compositions. Change point analysis of the cumulative number of anthropogenic fingerprints, using 13 subsets eliminating biases in data representation, indicates the onset of a rapid increase at 1952 ± 3 years (1 SD). However, excluding radionuclide signals, a rapid increase starts in the 1940s.
On the other hand, examining individual regions such as the Arctic, Antarctic, Europe, North America, East Asia, Oceania, and other regions, the maximum slopes of the cumulative number of anthropogenic fingerprints occurs in 1953-1957 (1955 ± 2.5 years), indicating a clear synchronicity in the timing of the maximum increasing rates in fingerprints between the regions. When excluding the radionuclide signals with simultaneity through short-time atmospheric diffusion over the globe, the maximum slopes are observed in all regions between 1949 and 1964 (1957 ± 8 years). The nearly-simultaneous explosion during this period represents a point where rapid, diverse, and intense anthropogenic modification spread out on a global scale, providing a clear rationale for the boundary that distinguishes the proposed Anthropocene from previous periods with diachronous local/regional human modification of the Earth environments. Between 1953-1957, the concentrated timing of the maximum slopes of the cumulative fingerprint number in each region, including the radionuclide data, implies that the radionuclide signal is a major factor forming the rapid increase point of anthropogenic fingerprints. However, if this signal is considered as one element constituting the overall acceleration of human disturbances against the Earth system, including diverse environmental, ecosystem, and material cycling changes, the nuclear test signal can be seen as a component of the Great Acceleration. The rapid increase in anthropogenic fingerprints, including the nuclear test signal, begins at the change point of 1952 ± 3 CE. Therefore, defining the beginning of the Anthropocene as the point when explosions of diverse anthropogenic fingerprints start spreading out globally, the age of the onset of the Anthropocene can be identified as 1952 ± 3 CE.