(CN) - The dramatic ecological decline sparked by human activity has led some scientists to argue the current geological epoch warrants a new name: the Anthropocene. But between the Industrial Revolution in the 1800s, the introduction of radioactive elements produced by nuclear bomb tests and other planet-changing human activities, determining the exact start of the Anthropocene is difficult.
Testing a potential marker of the beginning of the epoch, a team of researchers analyzed man-made contamination in lake sediments, which hold a record of past levels of synthetic compounds. Their findings were published Wednesday in the journal Environmental Science & Technology.
“Defining the start of the Anthropocene, as a formal geological unit of time, requires the presence of global markers, known as ‘golden spikes,’ recorded in rocks, sediment or glacier ice coupled with auxiliary stratotypes,” first author Aurea C. Chiaia-Hernandez told Courthouse News in an email.
“For example, the end of the Cretaceous period is clearly marked by the peaks of iridium levels worldwide when a meteorite collided with Earth 66 million years ago or the abrupt shift in deuterium (a hydrogen isotope) that marks formally the Holocene (which began about 12,000 years ago).”
Chiaia-Hernandez, a researcher at the Swiss Federal Institute of Aquatic Science and Technology in Switzerland, explained that identifying the start of the Anthropocene is more challenging than with other epochs as markers often vary from location to location.
To address this limitation, the scientists analyzed anthropogenic signals at two Swiss lakes, which provided a considerable volume of data for the team to explore.
“Therefore, our method offers the possibility to study thousands of anthropogenic markers from different input sources simultaneously,” Chiaia-Hernandez said.
Humans’ impact on the climate and environment began during the Industrial Revolution, and increased considerably over the second half of the 20th century. Several markers of human influence from waste disposal, the rising use of industrial chemicals like pesticides and pharmaceuticals, and other activities are featured in Earth’s sedimentary records.
The team applied high-resolution mass spectrometry to evaluate synthetic contamination at the lakes, examining 3.28-foot cores from each lake bottom that contain the past 100 years of sediment layers. The samples revealed that concentrations of industrial chemicals began to appear during the 1950s.
This aligns with the boom in industrial activities after World War II, which the researchers believe serves as the beginning of large-scale human impact on the environment.
According to Chiaia-Hernandez, the findings “show that the simultaneous analysis of different anthropogenic signals in different natural archives can provide important lessons on how humans are modifying the planet.”
The researchers will continue to study the Anthropocene, which they believe is significant for the recent past as well as the future outlook of the planet.
“Defining the start, but most importantly the formalization, of the Anthropocene is of great interest since to a large extent the future of the Earth is being determined by the actions of humans.”