(613c) Encouraging ‘Nature Positive’ Decisions: Toward an Open-Source Tool for Ecosystem Services-Based Absolute Environmental Sustainability Assessment

‘Nature Positive by 2030’ has become a widely accepted global goal which aims at halting and reversing nature loss by 2030 [1]. The stepwise temporal objectives of this goal are: Zero Net Loss of Nature from 2020, Net Positive by 2030, and Full Recovery by 2050 [2]. Reducing environmental impacts by mitigating emissions and resource use is not enough to achieve the 2030 goal. Restoration should be carried out immediately to reach the ‘Nature Positive’ milestone.

Virtually every definition of sustainability requires impacts of human activities to stay within nature’s carrying capacity [3,4]. However, conventional sustainability assessment methods such as life cycle assessment and carbon footprint ignore the role of nature. Its metrics indicate relative environmental sustainability based on comparing alternatives. Including nature’s carrying capacity as a reference, absolute environmental sustainability (AES) metrics are better at quantifying environmental sustainability. Incorporating anthropogenic impacts with the capacity of nature enables a bidirectional path towards a ‘Nature Positive’ world: reduce impact and restore nature simultaneously. Currently, many AES assessment methods rely on the planetary boundary (PB) framework which defined nine key earth system processes [5]. Each earth system process has a quantitative boundary which represents nature’s carrying capacity. These boundaries are calculated based on specific sustainability perspectives and are downscaled to a local context such as a process. Alternatively, the capacity of nature can also be considered as ecosystem services (ES) offered by ecosystems. The framework of Techno-ecological synergy (TES) is another AES assessment method that has been developed based on quantifying the availability of ecological goods and services [6]. TES-LCA expands the steps in conventional LCA to incorporate the demand and supply of ecosystem goods and services at multiple spatial scales [7]. TES and PB-based frameworks have been compared from methodological aspects [8]. Case studies of single unit process illustrate the value of using TES-based method in encouraging nature restoration.

Based on TES-LCA framework, this work is developing an open-source software for assessing alternatives and guiding decisions. Conventional LCA uses the equation, Am=f where A is the technology matrix which captures economic product flows between technological modules. m is a vector of scaling factors and f is a vector of final demands. The TES-LCA framework generates a bigger 'A' matrix by integrating the supply matrix S with the technology matrix A. This enables quantification of flows between technological and ecological modules. In other words, environmental impacts from technological modules can be compared with the absolute reference: supply from ecological modules. For conventional LCA, many life cycle inventory (LCI) databases have been developed. Similarly, for this TES-LCA software, we are building ecological data inventories that cover ES such as carbon sequestration, water provisioning, pollination, air and water quality regulation, etc. TES is a multiscale framework so the ecological data inventory captures ecosystem services (supply) data from different spatial scales. For instance, carbon sequestration data is considered from a region as small as a farm to a county to the whole world.

In TES-LCA, to access the absolute sustainability metric for a product system, supply data at coarser scales will be partially allocated to local contexts. Private and public ownership are considered for allocation. Supply at a local scale is assumed to be privately owned by the stakeholder. Thus, while using this software, local supply data for each process needs to be provided by the user. This local supply can be quantified through different biophysical models such as iTree [9], inVest [10], etc. which introduce high geographical resolution to results. If users do not have local supply data, we set default values for rough estimates.

This software is general and can be applied to any product/process system. A case study is conducted to illustrate how the software can be used and the value of using TES-LCA. Solar, hydro, wind, etc. are relatively clean sources of energy compared to fossil fuels. Solar energy has become one of the cheapest renewable sources whose life cycle GHG emission is 43 g CO2e/kwh compared to 486 g CO2e/kwh for fossil fuel [11]. However, ‘relatively good’ is not enough, there are still embodied carbon emissions coming from raw material mining, transportation, manufacturing, etc. Several of these activities can cause substantial loss of nature. To achieve the goal of ‘Nature Positive’, these emissions and impacts should be assessed with absolute metrics. The remaining emissions and other environmental impacts of solar power could be removed through nature-based solutions such as ecosystem services. For instance, air quality regulation and soil erosion control service for quartz mining, water quality regulation service for silicon refinery, etc. Considering the global nature of the solar panel value chain, AES assessment requires high geographical resolutions, which our TES-LCA software can easily handle.

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