Abstract
Land-use and land-cover changes (hereafter simply “land use”) alter climates biogeophysically by affecting surface fluxes of energy and water. Yet, near-surface temperature responses to land use across observational versus model-based studies and spatial-temporal scales can be inconsistent. Here we assess the prevalence of the historical land use signal of daily maximum temperatures averaged over the warmest month of the year (tLU) using regularized optimal fingerprinting for detection and attribution. We use observations from the Climatic Research Unit and Berkeley Earth alongside historical simulations with and without land use from phase 6 of the Coupled Model Intercomparison Project to reconstruct an experiment representing the effects of land use on climate. To assess the signal of land use at spatially resolved continental and global scales, we aggregate all input data across reference regions and continents, respectively. At both scales, land use does not comprise a significantly detectable set of forcings for two of four Earth system models and their multimodel mean. Furthermore, using a principal component analysis, we find that tLU is mostly composed of the nonlocal effects of land use rather than its local effects. These findings show that, at scales relevant for climate attribution, uncertainties in Earth system model representations of land use are too high relative to the effects of internal variability to confidently assess land use.
| Original language | English |
|---|---|
| Pages (from-to) | 1845-1861 |
| Number of pages | 17 |
| Journal | Journal of Climate |
| Volume | 36 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 15 Mar 2023 |
Bibliographical note
Funding Information:Acknowledgments. L. Grant and W. Thiery designed the analysis. L. Grant performed the analysis and wrote the manuscript. L. Gudmundsson and A. Ribes guided the detection and attribution methodology. D. M. Lawrence is a primary coordinator of the Land Use Model Intercomparison Project. All authors provided guidance on the analysis and contributed to writing the manuscript. D. M. Lawrence is supported by the National Center for Atmospheric Research, which is a major facility sponsored by the NSF under Cooperative Agreement 1852977, and by the U.S. Department of Energy, Office of Biological and Environmental Research Grant DE-FC03-97ER62402/A0101. R. S\u00E9f\u00E9rian acknowledges the European Union\u2019s Horizon 2020 research and innovation program under grant agreement No. 101003536 (ESM2025}Earth System Models for the Future). This study was supported by the LAMACLIMA project, part of AXIS, an ERA-NET initiated by JPI Climate, and funded by BELSPO (BE, Grant No. B2/181/P1) with co-funding by the European Union (Grant No. 776608). E. Robertson is supported by the Joint U.K. BEIS/ Defra Met Office Hadley Centre Climate Programme (GA01101). IPSL-CM6A-LR experiments were run on the HPC resources of TGCC under the allocations 2016-A0030107732, 2017-R0040110492 and 2018-R0040110492 (project gencmip6) provided by GENCI (Grand \u00C9quipe-ment National de Calcul Intensif) to conduct CMIP6 projects at IPSL. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation} Flanders (FWO) and the Flemish Government}department EWI.
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