Global Peak in Atmospheric Radiocarbon Provides a Potential Definition for the Onset of the Anthropocene Epoch in 1965

Abstract

Anthropogenic activity is now recognised as having profoundly and permanently altered the Earth system, suggesting we have entered a human-dominated geological epoch, the ‘Anthropocene’. To formally define the onset of the Anthropocene, a synchronous global signature within geological-forming materials is required. Here we report a series of precisely-dated tree-ring records from Campbell Island (Southern Ocean) that capture peak atmospheric radiocarbon (14C) resulting from Northern Hemisphere-dominated thermonuclear bomb tests during the 1950s and 1960s. The only alien tree on the island, a Sitka spruce (Picea sitchensis), allows us to seasonally-resolve Southern Hemisphere atmospheric 14C, demonstrating the ‘bomb peak’ in this remote and pristine location occurred in the last-quarter of 1965 (October-December), coincident with the broader changes associated with the post-World War II ‘Great Acceleration’ in industrial capacity and consumption. Our findings provide a precisely-resolved potential Global Stratotype Section and Point (GSSP) or ‘golden spike’, marking the onset of the Anthropocene Epoch.

New Insights From Pre-Columbian Land Use and Fire Management in Amazonian Dark Earth Forests

“…Although modern human influence over the Earth is substantial, there is considerable debate over when human activities began to dominate the planet's natural systems. Today, the extent of anthropogenic impact is so extensive that a new geological epoch, the Anthropocene, has been proposed (Ruddiman, 2003;Smith and Zeder, 2013;Castree, 2015;Waters et al, 2016;Turney et al, 2018). Defining the Anthropocene however, is complicated by the fact that the history of human land use and fire management is poorly characterized in large parts of the world that are known to have long histories of indigenous occupation, such as the Amazon Basin (Waters et al, 2016).…”

“…Defining the Anthropocene however, is complicated by the fact that the history of human land use and fire management is poorly characterized in large parts of the world that are known to have long histories of indigenous occupation, such as the Amazon Basin (Waters et al, 2016). Past human land use and fire management has the potential to alter the composition and structure of forest ecosystems, impacting fire susceptibility and creating an enduring anthropogenic legacy in modern ecosystems (Roberts et al, 2017;Levis et al, 2018;Maezumi et al, 2018;Turney et al, 2018). To date however very little is known about the history of human land use and fire management in the Amazon.…”

Anthropocene, the challenge for "Homo sapiens" to set its own limits

“…A synchronous and global signature within geological-forming materials is necessary to formally define the onset of any geological time division. The global peak in atmospheric radiocarbon due to thermonuclear bomb tests during the 1950s and 1960s, which has left recognizable footprints in tree-rings and sediments, provides a potential basis for the onset of the Anthropocene Epoch in 1965 (Turney et al, 2018). However, the term and its application to the geological time scales is subjected to intense discussion at the International Union of Geological Sciences (IUGS).…”

Visualizing Individual Tree Differences in Tree-Ring Studies

“…For example, in tree-ring studies, individual trees interact via competition or facilitation, which can lead to subsequent changes in forest structure (e.g., tree density, crown shape, above/below ground biomass allocation) [18][19][20][21], and further confound the explanation of tree-growth variability. Single trees are rarely the main focus of dendrochronological or dendroclimatological studies, with the possible exception of very old individuals or individuals, such as the "Loneliest Tree in the World" [22,23], however, increasingly, studies do analyze individual tree differences [21,[24][25][26][27][28][29][30][31].…”