Biogeochemical versus biogeophysical temperature effects of historical land-use change in CMIP6
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Abstract. Anthropogenic land-use change (LUC) substantially impacts climate dynamics, primarily through modifications in the surface biogeophysical (BGP) and biogeochemical (BGC) fluxes, which alter the exchange of energy, water, and carbon with the atmosphere. Despite the established significance of both the BGP and BGC effects, their relative contribution to climate change remains poorly quantified. In this study, we leveraged data from an unprecedented number of Earth system models (ESMs) of the latest generation that contributed to the Land Use Model Intercomparison Project (LUMIP), under the auspices of the Coupled Model Intercomparison Project Phase 6 (CMIP6). Our analysis of BGP effects indicates a range of global annual near-surface air temperature changes across ESMs due to historical LUC, from a cooling of −0.23 °C to a warming of 0.14 °C, with a multi-model mean and spread of -0.03±0.10 °C under present-day conditions relative to the pre-industrial era. Notably, the BGP effects indicate warming at high latitudes. Still, there is a discernible cooling pattern between 30° N and 60° N, extending across large landmasses from the Great Plains of North America to the Northeast Plain of Asia. The BGC effect shows substantial land carbon losses, amounting to -127±94 Gt C over the historical period, with decreased vegetation carbon pools driving the losses in nearly all analysed ESMs. Based on the transient climate response to cumulative emissions (TCRE), we estimate that LUC-induced carbon emissions result in a warming of approximately 0.21±0.14 °C, which is consistent with previous estimates. When the BGP and BGC effects are taken together, our results suggest that the net effect of LUC on historical climate change has been to warm the climate. To understand the regional drivers (and thus potential levers to alter the climate), we show the contribution of each grid cell to LUC-induced global temperature change, as a warming contribution over the tropics and subtropics with a nuanced cooling contribution over the mid-latitudes. Our findings indicate that, historically, the BGC temperature effects dominate the BGP temperature effects at the global scale. However, they also reveal substantial discrepancies across models in the magnitude, directional impact, and regional specificity of LUC impacts on global temperature and land carbon dynamics. This underscores the need for further improvement and refinement in model simulations, including the consideration and implementation of land-use data and model-specific parameterizations, to achieve more accurate and robust estimates of the climate effect of LUC.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it