The novel entities boundary in the planetary boundaries framework refers to entities that are novel in a geological sense and that could have large-scale impacts that threaten the integrity of Earth system processes.

This perspective is based on a review of the scientific literature relevant to quantifying the boundary for novel entities and highlights plastic pollution as a particular aspect of high concern. An impact pathway from production of novel entities to impacts on Earth system processes is presented.

The authors define and apply three criteria for assessment of the suitability of control variables for the boundary: feasibility, relevance and comprehensiveness. They propose several complementary control variables to capture the complexity of this boundary, while acknowledging major data limitations.

They conclude that humanity is currently operating outside the planetary boundary based on the weight-of-evidence for several of these control variables. The increasing rate of production and releases of larger volumes and higher numbers of novel entities with diverse risk potentials exceed societies’ ability to conduct safety related assessments and monitoring.

The authors recommend taking urgent action to reduce the harm associated with exceeding the boundary by reducing the production and releases of novel entities, noting that even so, the persistence of many novel entities and/or their associated effects will continue to pose a threat.