Global decarbonization-biodiversity tradeoffs of future alternative electrification strategies

Ryan McManamay, Department of Environmental Science, Baylor University, Waco, TX, Henriette (Yetta) Jager, Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN and Chris Vernon, Pacific Northwest National Laboratory, Richland, WA

Background/Question/Methods: Reducing emissions can help to avert a ‘sixth extinction’ produced by climate change. However, addressing climate mitigation while also meeting global electrification goals will require transformative changes to the energy sector, primarily a reduction of fossil fuel dependence replaced by large-scale renewable energy deployment. Whereas subterranean fossil fuel sources are energy dense, renewable energy infrastructure expansion requires significant land assets per unit energy. The shift in energy source could therefore come at high cost to ecosystems, creating potential conflict between global climate and biodiversity conservation. Here, we explore the potential land requirements and biodiversity implications of alternative future global electrification pathways as depicted under the Shared Socioeconomic Scenarios (SSPs). We examined the intersection of high-resolution estimates of global energy densities for ten renewable and conventional technologies with global richness data to estimate biodiversity footprints (species per GWh) for each technology. Regionally explicit electricity generation scenarios (2020 to 2100) were downscaled to 50-km depictions of future technology deployment and were additionally constrained by scenarios of protected land exclusion and variant local energy development policies. Biodiversity footprints were used to explore land and biodiversity impacts through a Cumulative Biodiversity Impact (CBI) score.
Results/Conclusions: Unexpectedly, variation among SSPs did not exhibit a clear tradeoff between global climate mitigation and biodiversity conservation (CBI). Rather, CBIs were an outcome of total infrastructure development to meet total electricity demand and the total magnitude of renewable energy development and storage technologies. SSP5 (fossil-fueled) development scenarios consistently had the highest CBI values due to higher future electricity demands, whereas scenarios with lower demands (e.g., SSP3), had the lowest CBI values. SSP1 (sustainability) scenarios, characterized by higher deployment of renewable energy, had moderate CBI values. Renewable sources can be viewed along a spectrum from land sharing to sparing. At the land sharing end of the spectrum, biopower (biomass for electricity generation) from dedicated crops contributed the most to biodiversity impacts due, in part, to its low energy density. At the land-sparing end of the spectrum, higher energy density sources (e.g., solar) cause more-intense land degradation, but in smaller areas. The convergence among SSPs suggests that land conservation practices and local strategies aimed at promoting energy diversification could have greater implications for future biodiversity conflicts than which socioeconomic pathways are followed. Our analysis suggests that there is great uncertainty in how future global electrification pathways will influence biodiversity depending on local land use and conservation policies.