A global team of scientists, anchored by researchers from the University of Maine in the United States, has explored Crawford Lake in Canada as a potential benchmark for a proposed new geological age—the Anthropocene. Their findings have been shared at conferences organized by leading climate science institutions, including gatherings hosted by the Max Planck Society, which focuses on climate research and related topics.
The term Anthropocene refers to a span in Earth’s history marked by distinctive human impacts that leave a recognizable imprint on terrestrial sediments. Scientists have long considered various locations as possible starting points for this new epoch, including tropical coral reefs in North America and Australia, peat bogs in the Polish mountains, and ice sheets in Antarctica, as well as human remains studied in European contexts. Ultimately, Crawford Lake, situated just outside the Toronto region in Canada, emerged as a leading candidate for this milestone in stratigraphy.
According to Andrew Candy, a geoscience expert affiliated with the University of Southampton, the trace amounts of plutonium found in annual sediment layers at Crawford Lake provide a tangible signal of when human activities began to shape the planet on a global scale.
Plutonium occurs naturally only in minute quantities, but its worldwide presence surged in the early 1950s following the atmospheric testing of thermonuclear weapons. This distinctive chemical signature helps researchers pinpoint a time horizon in the sediment record when anthropogenic influence became globally detectable, a key criterion for defining the Anthropocene boundary.
Over many years, the Anthropocene Working Group has pursued a rigorous search for a verifiable “golden nail” that could anchor the formal recognition of the epoch. Comprising geologists, geographers, and chemists from around the world, the AWG operates under the auspices of the International Commission on Stratigraphy. Its members have methodically evaluated a wide array of candidate records and sites to establish a robust, globally recognizable starting point for the Anthropocene.
In the current assessment, the team concluded that the sediment deposits at the base of Crawford Lake over recent millennia present the clearest evidence of a transition in planetary conditions caused by human activity. The next step involves transferring the collected rock samples from the lake bottom to the authorities responsible for stratigraphic standardization. Pending review and approval by these governing bodies, the proposed start date of the Anthropocene could receive formal international endorsement, marking a new milestone in the science of Earth’s history.
Earlier studies by researchers affiliated with Michigan State University highlighted that freshwater lakes can be more vulnerable to certain forms of pollution, including microplastics, than ocean environments. This realization underscores the importance of lakes as valuable archives for documenting environmental change and the footprint of human activity across continents.