New research supports the concept of the Anthropocene Epoch, a proposed geological time period marked by significant human impact on the Earth. The study analyzed vegetation changes in North America since the end of the Pleistocene Epoch using fossil pollen data. Their findings indicate that recent changes in vegetation are comparable to those observed during the last epochal transition, suggesting a significant shift in ecosystem functioning that warrants the classification of a new epoch.
Researchers have determined that human activity has shaped the environment as significantly as the glacial retreat at the end of the Ice Age.
Scientists have long debated the Anthropocene Epoch, a proposed unit of geologic time corresponding to the most recent period in history. It’s characterized by substantial human impact on the planet.
Are we living in the Anthropocene? And if we are, then when did it start?
In a research article published this month in The Proceedings of the National Academy of Sciences, The University of Toledo’s Dr. Trisha Spanbauer and Stanford University’s Dr. M. Allison Stegner lend credence to the argument for its existence. The pair analyzed open-source data to track vegetation changes across North America since the end of the Pleistocene Epoch, and concluded that humans have had as much of an impact on the landscape as the retreat of the glaciers at the end of the Ice Age.
Study Methodology
“As a paleolimnologist, I’m very interested in what the past can tell us about the future,” said Spanbauer, an assistant professor in the Department of Environmental Sciences. “Biotic changes have been used to demarcate epochs in the past, so this analysis gives us valuable context to understand if what we’re seeing today is fundamentally similar in magnitude to what we would have seen at the shift between the Pleistocene Epoch and the Holocene Epoch.”
Spanbauer and Stegner utilized the Neotoma Paleoecology Database, a community-curated repository for multiple kinds of paleoecological data. They specifically looked at fossil pollen data sourced from 386 sediment cores records taken from lakes across North America.
Sediment cores are samples taken from the bottom of a lake that preserve the depositional sequence. Spanbauer and Stegner considered samples taken as early as the late Pleistocene – around 14,000 years ago.
Analyzing Ecological Changes
They analyzed the data according to seven metrics: taxonomic richness, meaning the diversity of pollen speciesA species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>species; first appearance datum, last appearance datum, and short-term gain and loss of taxa, measuring the frequency with which species appear and disappear in fossil records; and abrupt community changes, referring to species identified in the samples. They organized their data points within 250-year time periods and on both continental and regional scales, and incorporated age-model uncertainty, and accounted for differences in sample size to generate conservative estimates.
Their results indicate that vegetation changes within the last few hundred years are comparable to those accompanying the last epochal transition, including increases in first and last appearances as well as abrupt community changes.
“The power of a database like this is that we’re able to ask questions about macroscale ecological changes,” Spanbauer said. “Scientists have documented the effects of human activity on single species and on biodiversity in general, but our research puts these observations into a much broader context. It indicates a change in how ecosystems are functioning that supports the delineation of a new epoch.”
Reference: “North American pollen records provide evidence for macroscale ecological changes in the Anthropocene” by M. Allison Stegner and Trisha L. Spanbauer, 16 October 2023, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2306815120
Source: SciTechDaily
