Evaluating asset-level impacts: mining
This approach can also be used for more detailed evaluations of impacts where assessments at the level of individual assets is desired and feasible. As an example, we analyze individual lithium mining assets. We integrated a dataset on the location of 23 global lithium mines with high-resolution (~5m) satellite imagery29 to map the footprint of individual mines. We then combined these footprints with the global maps of ecosystem service and biodiversity values to calculate mine impacts. These impacts account for both mine location and the mine-specific area of land impacted.
Our results show that the magnitude of impact varies substantially among mines (Figure 4). The range of potential impacts of lithium mining on nature are determined by the location of Earth’s lithium reserves relative to the location of ecosystem service and biodiversity hotspots, but even given this constraint, there are options for acquiring lithium with higher or lower costs to ecosystem services and biodiversity. This asset-specific information can be weighed alongside information such as differences in productivity and operation costs. Understanding the impacts of specific assets or project footprints on natural capital can help project developers, corporates, infrastructure investors, and other decision makers limit their negative impacts and optimize for production efficiency when evaluating investments in new or existing development.
Using high-resolution, asset-specific footprints also reveals the impacts of many lithium mines to be much higher than estimated by assuming a fixed, median size (Figure 4a). The fixed approach is generally able to differentiate between high- and low-impact mines for the ecosystem services of sediment retention and nitrogen retention but was not as effective at distinguishing differences for biodiversity (Figure 4b). Assuming a median area by asset type may be both necessary and sufficient when comparing across many assets, such as when comparing across thousands of companies. However, where feasible, asset-specific footprints provide valuable additional information and spatial precision in assessing impact, especially when comparing among assets within an activity type or analyzing an asset over time. Of the 23 lithium mines evaluated, the mine with the largest footprint (Chaerhan Lake, China at >3,250 km2) is the most impactful mine on endemic species, Red List species, and species richness, but other mines had greater impacts on the other four measures. None impacted coastal risk reduction. Five different mines represent the highest impact mines across all seven metrics. Four of these five are in China, which contains 8 of the 23 total lithium mines assessed.
Our approach can also leverage high resolution, high frequency satellite imagery to assess how a mine’s footprint – and associated impact – changes over time. Combining the mine footprint with high resolution ecosystem service and biodiversity maps is important because these impacts do not necessarily scale linearly with footprint area or production. Using the Greenbushes, Australia lithium mine as an example, with annual satellite imagery29 and production data from 2016-202330, we find that the mine’s total footprint increased around 75 percent, while annual production increased around 140 percent (Figure 5, Table S2). Impacts to nitrogen retention, sediment retention, and species richness each increased over 80 percent, slightly more than would be expected by the change in footprint size alone, indicating the mine expanded into higher impact areas over time. In contrast, impacts to nature access, habitat for endemic species, and habitat for threatened and endangered species increased slightly less than the increase in footprint size. Across all ecosystem service and biodiversity measures, the impact per tonne of lithium produced decreased between 2016 and 2023, apart from a period of low production around 2021 likely due to COVID-19. Given that demand for lithium is increasing and will likely continue to in a transition to a lower carbon economy23,24, intensity metrics can help show which areas produce the most while limiting negative environmental impacts.
Capturing this level of granularity can help project developers and investors explore the impact of an asset over time and analyze whether a possible increase in negative impact due to a larger asset footprint is justified by a meaningful increase in production. In addition to evaluating past trends, the high-resolution ecosystem service and biodiversity impact maps could also contribute to implementation of the mitigation hierarchy at the asset level31, enabling project developers to avoid and minimize impacts to the most sensitive locations. The ability to compare impacts among mines can help guide extraction towards more sustainable options for this important resource.