Urban Projections
Global projected impact of urban land expansion on species habitats to 2050 under three Shared Socio-economic Pathway scenarios. Layers from Simkin et al. 2022.
Impacts of urban expansion projected to 2050
Maps accompanying Simkin et al.
Background
The global urban population is poised to grow by 2.5 billion over the next 30 years, and urban land is expected to expand to accommodate them - up to triple its 2015 extent by 2050. Urban land conversions are expected to be an increasingly prominent driver of habitat and biodiversity loss over this period. Mitigating these impacts urgently requires an improved understanding of where and how these biodiversity losses might occur.
Here we use a recently developed suite of new land-use projections to provide an assessment of the habitat lost to land-use change, and urban land expansion specifically, for 30,393 species of terrestrial vertebrates 2015 -2050. Within each species' known range we identify suitable habitat - termed Habitat-suitable Range (HSR) - based on habitat preferences and elevation, and project how this will change in the future.
The assessment identifies global urban impact hotspots by assessing the impacts of individual clusters of urban land. The urban clusters are contiguous units of urban land, independent of administrative boundaries estimated to be at least 400 km2 in size in 2050. Urban land expansion within the hotspot clusters are responsible for 70 - 75% of the predicted HSR lost to urban expansion amongst the most heavily impacted species, but collectively represent around one-third of predicted new urban land.
We assess the impacts to species across three Shared Socioeconomic Pathway (SSP) scenarios representing plausible global development pathways. We compare a sustainability scenario (SSP1), a regional rivalry scenario (SSP3) and a fossil fueled development scenario (SSP5). The three SSPs differ both in terms of expected urbanization rates, and pressures on habitat.
Our findings highlight the urgent need for an increased focus on urban land in global conservation strategies and identify high-priority areas for this engagement.
Full details of this study can be found at:
Simkin, R.D., Seto, K.S., McDonald, R.I. & Jetz, W., 2022, Biodiversity impacts and conservation implications of urban land expansion projected by 2050, Proc. Natl. Acad. Sci. U.S.A., https://www.pnas.org/cgi/doi/10.1073/pnas.2117297119
