(49b) Planetary Boundaries, Ecosystem Services, and Life Cycle Assessment – Novel Insight By a Case Study and Computational Framework

Recent extensions of life cycle assessment are including the role of ecosystems and nature’s carrying capacity. Such extensions are needed to ensure that decisions toward sustainability respect nature’s limits and do not cause unintended harm by ecosystem degradation. Such approaches are essential to meet the basic requirement of sustainability, which is to keep human activities within the earth’s carrying capacity.

In this work, we compare two such extensions: planetary-boundary-based LCA (PB-LCA) [1,2] and techno-ecological synergy in LCA (TES-LCA) [3,4]. PB-LCA is based on the planetary boundary framework developed by Rockström and colleagues. PB framework defined nine key Earth System processes and identified quantitative ‘Planetary boundaries’ which delimit a “safe operating space” for humanity to stay within [5]. Approaches have been developed by including the PB-framework in LCA [1]. The original PB-LCA method downscales 9 planetary boundaries to smaller scales and allows to find out whether the environmental impact of an activity is sufficiently low for it to be considered as environmentally sustainable. However, according to the first planetary boundary paper, downscaling boundaries is not recommended [6]. TES-LCA expands the steps in conventional LCA to incorporate the demand and supply of ecosystem goods and services at multiple spatial scales. This enables the calculation of local and absolute environmental sustainability metrics and helps identify improvement opportunities by protecting and restoring ecological systems.

In comparing the PB-LCA and TES-LCA frameworks, we find that both frameworks can evaluate how the assessed activity contributes to occupying the Earth’s carrying capacity which in line with the idea of absolute sustainability [2]. These two methods identify potential hotspots in the life cycle, quantify spatial specific supply, demand and characterization factor which break the limitation of geographical resolution. Relationships between 9 planetary boundaries and 24 ecosystem services are studied in this work. Multiple ecosystem services could contribute to one planetary boundary. In general, there are 3 main differences between PB and ES framework: scope, categories included in the framework and the way to define the threshold. The scope of PB framework is planetary while for ES framework it’s multiscale such as local and serviceshed scale. For the categories, each of the 9 planetary boundaries is related to an ecosystem service such as climate change boundary responses to the carbon sequestration service. However, not every ecosystem service has a corresponding planetary boundary. For example, pollination, air and water quality regulation, and cultural services do not have a direct boundary. The last point is how these two frameworks define the limit. In PB-LCA, the PB is directly downscaled to process-level, but in TES-LCA, process-level supply consists of local supply and allocation of serviceshed supply. Recently, works have been done on localized boundaries [7] which is similar to the local supply in TES-LCA. Comprehensive comparisons of such concepts, terminologies, and governing characterization factors have been done for these two frameworks.

Aiming at accounting for absolute sustainability and intuitive comparison, these two methods are demonstrated based on comparing the life cycles of products from biomass versus conventional sources. It involves multiple planetary boundaries like climate change and global freshwater use boundaries; multiple ecosystem services including carbon sequestration, water provisioning, etc. Different allocation principles like demand-based, GDP-based are used and compared for downscaling boundary and ecosystem services allocation. Compared with PB-LCA, TES-LCA not only downscales ES of the serviceshed which the process located in, but also takes ES’s ownership and finer local-level ES into account. To enable practical use of these methods, computer implementation is developed and applied with an emphasis on climate change, water provisioning, etc. This computational framework accounts for spatial variation, aggregates geographically resolved environmental impact from process-level to larger scales like state-level, and global-level and it could be used for both PB-LCA and TES-LCA. A general computer framework is coded in python for further development into a user-friendly software tool.

Based on this work, we find that there are three main differences between planetary boundary and ecosystem service framework, however despite these differences, PB-LCA and TES-LCA show high similarity and can converge to one general framework under specific conditions. We show how this insight can be sued to develop inventory datasets and tools for practical application of these approaches.

1. Ryberg, Morten W., et al. "Development of a life-cycle impact assessment methodology linked to the Planetary Boundaries framework." Ecological Indicators 88 (2018): 250-262.

2. Bjørn, Anders, et al. "A proposal to measure absolute environmental sustainability in life cycle assessment." Ecological Indicators 63 (2016): 1-13.

3. Liu, Xinyu, and Bhavik R. Bakshi. "Ecosystem services in life cycle assessment while encouraging techno‐ecological synergies." Journal of Industrial Ecology 23.2 (2019): 347-360.

4. Bakshi, Bhavik R., Guy Ziv, and Michael D. Lepech. "Techno-ecological synergy: A framework for sustainable engineering." Environmental science & technology 49.3 (2015): 1752-1760.

5. Rockström, Johan, et al. "A safe operating space for humanity." nature 461.7263 (2009): 472-475.

6. Rockström, Johan, et al. "Planetary boundaries: exploring the safe operating space for humanity." Ecology and society 14.2 (2009).

7. Bjørn, Anders, et al. "Life cycle assessment applying planetary and regional boundaries to the process level: a model case study." The International Journal of Life Cycle Assessment 25.11 (2020): 2241-2254.