Defining the risk presented by novel entities: How plastic and chemicals affect Earth system integrity

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Illustration

Illustration of the article by Persson et al (2022).

The planetary boundaries framework has been introduced to define a safe operating space for human activity. Novel entities, which include chemical and plastic pollution, has previously been identified as one of nine planetary boundaries, but not quantified. The authors of the research article summarized here suggest methods for quantification, and by using the methods, conclude that humanity is currently not within the safe operating space of the novel entities planetary boundary. Immediate action to manage threats is necessary, and actions must be carried out in parallel with continued research.

Authors

Linn Persson, Swedish Society for Nature Conservation and Stockholm Environment Institute; Bethanie M. Carney Almroth, Department of Biology and Environmental Sciences, University of Gothenburg; Christopher D. Collins, Department of Geography and Environmental Sciences, University of Reading; Sarah Cornell, Stockholm Resilience Centre, Stockholm University; Cynthia A. de With, department of Environmental Science, University of Stockholm; Miriam L. Diamond, Department of Earth Sciences and School of the Environment, University of Toronto; Peter Fantke, Quantitative Sustainability Assessment, Department of Technology, Management and Economics, Technical University of Denmark; Martin Hassellöv, Department of Marine Sciences, University of Gothenburg; Matthew Mac Leod, Department of Marine Sciences, University of Gothenburg; Morten W. Ryberg, Quantitative Sustainability Assessment, Department of Technology, Management and Economics, Technical University of Denmark; Peter Sørgaard Jørgensen, Stockholm Resilience Centre, Stockholm University; Patricia Villarrubia-Gómez, Stockholm Resilience Centre, Stockholm University; Zhanyun Wang, Institute of Environmental Engineering, ETH Zürich; Michael Zwicky Hauschild, Institute of Environmental Engineering, ETH Zürich

 

  • Novel entities are created and introduced into the environment by humans, and can have disruptive effects on the earth system. The novel entities boundary is one of nine planetary boundaries, defined to monitor a safe operating space for humanity.
  • The planetary boundary of novel entities is exceeded, as annual production and releases are increasing at a pace that exceeds the global capacity for assessment and monitoring
  • Along with chemical pollution, plastic pollution is highlighted as a particular aspect of high concern among novel entities
  • A set of complimentary control variables measuring trends of production, emission and impacts are suggested to quantify the planetary boundary and establish a safe operating space
  • Immediate action aiming to prevent harm before the stage of Earth system effects should be taken even though data collection and parameter definition is still going on.

Planetary boundaries and the novel entities

The theoretical concept of planetary boundaries (PBs) has been introduced to define biophysical thresholds that could have severe consequences for the Earth and humanity if overstepped, creating a safe operating space for humanity within the boundaries. Originally nine planetary boundaries were defined 1, including chemical pollution, which was not yet quantified at the time of definition. As work with quantification has been proceeding, the chemical pollution planetary boundary has been renamed to novel entities (NEs), and the definition changed to include “new substances, new forms of existing substances and modified life forms” 2. In other words, the novel entities planetary boundary includes substances that are created, introduced, or recirculated by humans – like plastics and chemicals. This is complex, as it includes a large range of known and unknown substances, which can have diverse direct and indirect effects on the Earth system. The scientific discussion around options for its quantification has focused on chemical and plastic pollution. Efforts to define the NE-PB are still ongoing, focusing on defining methods for quantification.

«We focus on chemical pollution, highlighting plastic pollution as a particular subset issue of high concern, and provide an assessment of the current status of this planetary boundary”

Credit: Designed by Azote for Stockholm Resilience Centre, based on analysis in Persson et al 2022 and Steffen et al 2015.

Quantifying the novel entities planetary boundary

Quantification of boundaries for novel entities requires defined control variables for measuring effects. Identifying suitable control variables is complicated as there is primarily no prehuman background level or baseline of novel entities available for comparisons, and because of the number and diversity of novel entities, the likelihood of increase in the future, and the diverse possible impacts are unclear. Complex and diverse impact mechanisms mean that no single control variable can capture the full scope of the safe operating space for novel entities. Therefore, quantification in terms of trends or pressures in an impact pathway approach rather than system conditions, may be more appropriate.

This approach opens for many possible control variables, and thus a set of criteria is needed to evaluate their qualities. The authors present three such criteria:

Feasibility (F): Can it be measured? Data availability must permit quantification at relevant spatial and temporal scales and comparison with other biophysical monitoring data

Relevance (R): Can it be robustly linked to effects? It must be possible to link the control variable consistently to one or more effects that are known to influence Earth system functioning, i.e., establish a cause-effect link

Comprehensiveness (C): Does it capture the planetary scale of the problem? The control variable must indicate the totality of the potential impacts of novel entities, through cause-effect thresholds affecting a given Earth system process or thorough effects on one or more of the other PBs.

The authors identify possible control variables for quantification of the NE-PB and evaluate them in the F/R/C framework, as presented in Figure 1:

Production of novel entities, consisting of trend in production volumes of chemicals, trend in production volumes of plastics and the share of chemicals on the market that are assessed for risk or safety.

Trend in release of novel entities, consisting of emissions of hazardous chemicals and release of plastic to the environment

Unwanted impact of novel entities of earth system processes, as well as the effect-focused control variable plastics’ disturbances to biosphere integrity.

Evaluation of the suggested control variables in the F;R;C-framework. The figure is adapted from Persson et al (2022) Figure 1 and Table 1.

None of the suggested control variables fulfill all the criteria by themselves, and they all range in feasibility, relevance, and comprehensiveness. Thus, the authors suggest that the presented variables in combination can form the basis for evaluating the risk caused by novel entities, and that using them as a set of control variables to quantify the NE-PB is a suitable way to capture its complexities and characteristics.

Are we transgressing the planetary boundary for novel entities?

To answer this question, the authors use a weight-of-evidence approach by comparing the rate of change in the amount of chemicals and plastics that are produced and released to the environment relative to the world´s capacity to conduct safety assessments and monitoring. The safe operating space of the NE-PB is considered exceeded when annual production and releases increase at a pace that outstrips the global capacity for assessment and monitoring.

“Increases in production and releases of novel entities are not consistent with keeping humanity within the safe operating space.”

Using the defined control variable set, the authors observe a consistent increase over time in production, diversity, and global releases of NEs. Safety assessments and subsequent regulations are currently not keeping up with the speed of introduction of new NEs, despite major efforts in recent decades, such as through the EU REACH regulation and the global Stockholm Convention. Based on this evidence, the authors suggest that we are currently in a zone of exceedance of the NE-PB. As many NEs are persistent in the environment, negative effects will still be a threat even if production is stabilized or reduced. In conclusion, increases in production and releases of novel entities are not consistent with keeping humanity within the safe operating space.

Actions to mitigate current damage and avoid future surprises

The authors invite the research community to use the understanding of the NE-BP presented in the article to continue developing more robust quantification and better-defined limits for NE emissions. However, these continued research efforts need to go in parallel with urgent action to manage today’s NE-PB threats. Immediate preventative action before the stage of Earth system effects should be taken even though data collection and parameter definition is still ongoing.

Measures to reduce releases and emissions of NEs to the environment are essential, including a higher degree of circularity in product supply chains, material and product design, design for recycling, and safe and sustainable chemicals. Calls for establishing caps on plastic production and use, similar to existing caps on greenhouse gas emissions, have been made. The authors suggest that the same approach is needed for all NEs. Getting back within the safe operating space can only be achieved through globally capping emissions of NEs at a rate that meets the physical and chemical capacity of the Earth system.

“Immediate action aiming to prevent harm before the stage of Earth system effects should be taken even though data collection and parameter definition is still going on.”

If we are to mitigate current damage and avoid future risk from unknown NE-PB threats, a more preventive and precautionary hazard-based approach is needed to address novel entities. The authors acknowledge that reducing chemical and plastic releases is a considerable challenge and suggest that the international science-policy body with oversight over chemicals and waste, which has recently been called for, may provide a forum for informing actions that are needed to help safeguard the Earth system.

Read the whole article here: Outside the Safe Operating Space of the Planetary Boundary for Novel Entities

Learn more in The Burning Case podcast episode – Pushing the toxic boundary: chemical pollution, planetary boundaries and science in media.

References

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