Quantifying Biodiversity Loss: Linking Greenhouse Gas Emissions to Sea Level Rise

A major driver of biodiversity loss is climate change caused by greenhouse gas (GHG) emissions from global production, trade, and consumption. A tool to consistently quantify GHG emission and their impact on biodiversity along entire value chains is life cycle assessment (LCA). In LCA, emissions and resource use are linked with their effects via impact pathways. Although highly relevant, many impact pathways leading from climate change to damages on biodiversity are still incomplete or entirely missing.

One critical but still missing impact pathway is sea level rise (SLR), which is driven by GHG emissions through climate change. SLR contributes to flooding of terrestrial areas, coastal erosion, and freshwater salinization. Without adaptation, the risk of habitat loss in coastal ecosystems is projected to increase tenfold by 2100, particularly endangering low-lying and erosion-prone ecosystems. These ecosystems host highly diverse and endemic species, often at risk of large-scale habitat loss, potentially resulting in severe declines in local and global biodiversity.

To quantify the impacts of SLR on biodiversity loss, we developed a globally differentiated flood model using the latest SLR projections from IPCC for five Shared Socioeconomic Pathways (SSPs).  As SLR projections are driven by temperature increases, we linked them to GHG emissions through the time-integrated Absolute Global Temperature Potential (AGTP). Flood-induced habitat loss was connected to biodiversity decline through the countryside species–area relationship (c-SAR), accounting for different land cover types and land use intensities. The results are spatially differentiated at ecoregion level and expressed as the potentially disappeared fraction of species (PDF) as a metric for species richness for five terrestrial taxa.

Using the developed impact pathway, ecoregions at high risk for local species extinction and those contributing most to global species loss can be identified. Moreover, the resulting factors directly link GHG emissions to SLR-induced biodiversity loss and can thus be readily integrated into the LCA framework to better account for companies’ and products’ impacts on biodiversity.