The potential of Municipal Solid Waste (MSW) layers as Anthropocene strata

For the Anthropocene to get recognized as a real geological era, first and foremost its strata must be identified. Several geological formations such as bogs, lakebeds, reefs, ice sheets, speleothems, river estuary deposits, and sea floors have been considered as potential candidates for the Anthropocene strata. This consideration arises from the emergence of novel materials associated with the Anthropocene, including radioactive isotopes, plastics, and aluminum, started to be discovered in their sediments and dramatically increased since the mid-20th century. Yet, these deposits are no longer considered ‘natural’ because human activities are largely controlling the transport and depositional processes from source to sink. The Municipal Solid Waste (MSW) in landfills has been also ‘unnaturally’ transported and deposited (landfilled) by humans. Since the 1950s, the controlled landfills have been made worldwide, and thus the opening time of the landfills is clear. The MSW layers of landfills, which appeared globally, contemporaneously, and with distinct characteristics, are indeed the ‘artificial (anthropogenic)’ strata showing a new and clear aspect of human influence, unprecedented in geological time. The MSW layers can be considered valuable indicators of the Anthropocene era because they not only preserve the history of human life but also sensitively demonstrate the scale of human activities like mass production, consumption, and disposal. The MSW layers can be expected to serve as a unique window into the Anthropocene.