SSP-Based Land-Use Change Scenarios: A Critical Uncertainty in Future Regional Climate Change Projections
Date
2021-03-25
Journal Title
Journal ISSN
Volume Title
Publisher
Earth's Future
Abstract
To better understand the role projected land-use changes (LUCs) may play in future regional climate projections, we assess the combined effects of greenhouse-gas (GHG)-forced climate change and LUCs in regional climate model (RCM) simulations. To do so, we produced RCM simulations that are complementary to the North-American Coordinated Regional Downscaling Experiment (NA-CORDEX) simulations, but with future LUCs that are consistent with particular Shared Socioeconomic Pathways (SSPs) and related to a specific Representative Concentration Pathway (RCP). We examine the state of the climate at the end of the 21st century with and without two urban and agricultural LUC scenarios that follow SSP3 and SSP5 using the Weather Research and Forecasting (WRF) model forced by one global climate model, the MPI-ESM, under the RCP8.5 scenario. We find that LUCs following different societal trends under the SSPs can significantly affect climate projections in different ways. In regions of significant cropland expansion over previously forested area, projected annual mean temperature increases are diminished by around 0.5°C–1.0°C. Across all seasons, where urbanization is high, projected temperature increases are magnified. In particular, summer mean temperature projections are up to 4°C–5°C greater and minimum and maximum temperature projections are increased by 2.5°C–6°C, amounts that are on par with the warming due to GHG-forced climate change. Warming is also enhanced in the urban surroundings. Future urbanization also has a large influence on precipitation projections during summer, increasing storm intensity, event length, and the overall amount over urbanized areas, and decreasing precipitation in surrounding areas.
Key Points
- Local-to-regional climate change projections of temperature and precipitation are strongly influenced by urban and agricultural land-use changes
- Different shared-socioeconomic-pathway-informed land-use changes produce different responses in future regional climate changes
- Urban land expansion has a greater influence on the contiguous United States climate change projections than agricultural land expansion
Plain Language Summary
In many regional climate change studies, projections of future climate conditions are produced assuming the current spatial distribution of different land cover types (e.g., urban, cropland, forest, etc.) will stay the same, even for long-term futures. In doing so, they neglect potential impacts of human land-use changes (LUCs) on regional climate, and miss the opportunity to identify potential land-use strategies that could moderate felt climate change effects. In this study, we model urban and agricultural LUCs following two pathways with different social and environmental trends throughout the 21st century, and investigate how the LUCs might affect climate change in North America. We find that future LUCs can strongly influence projections of temperature and precipitation. Generally, urban land expansion casted a larger impact than agricultural land expansion. In areas where croplands replace forests, the temperature increase caused by greenhouse gas warming is reduced, while in and near future urban areas, the temperature increase caused by greenhouses gas warming is doubled by warming effects from urban land expansion. Meanwhile, urban expansion enhances precipitation over urbanized areas making rainfall events heavier and longer, while precipitation in the surrounding areas is reduced.
Description
This article was originally published in Earth's Future. The version of record is available at: https://doi.org/10.1029/2020EF001782. © 2021. The Authors.
Keywords
CORDEX, land-use change, regional climate, SSP, climate action
Citation
Bukovsky, M. S., Gao, J., Mearns, L. O., & O'Neill, B. C. (2021). SSP-based land-use change scenarios: A critical uncertainty in future regional climate change projections. Earth's Future, 9, e2020EF001782. https://doi.org/10.1029/2020EF001782