Local and Non‐Local Biophysical Impacts of Deforestation on Global Temperature During Boreal Summer: CMIP6‐LUMIP Multimodel Analysis

Abstract

Biophysical effects of forest cover changes are often neglected by climate policies and recent state‐of‐the‐art climate models exhibit wide spreads in simulating the biophysical impacts of deforestation. By using the CMIP6‐LUMIP simulations, here we examined the biophysical impacts of deforestation on global temperature and attributed deforestation‐induced surface temperature change to different biophysical effects (i.e., radiative forcing, aerodynamic resistance, Bowen ratio and atmospheric feedbacks) at regional scales. Results show that models agree on the sign of temperature responses to different biophysical factors in the tropics, but exhibit wide divergence in the extratropical regions. Among the three local biophysical factors (i.e., radiative forcing, aerodynamic resistance, and Bowen ratio), aerodynamic resistance contributes largely to local surface warming in models. As the local effects rarely affect the areas away from the deforested regions, much of the modeled discrepancies result from non‐local atmospheric feedbacks in the middle and high latitudes. Our results suggest that climate responses to deforestation have a large spread in current models and highlight the need to improve our understanding and modeling of non‐local effects in the biophysical impacts of deforestation.

Important non-local effects of deforestation on cloud cover changes in CMIP6 models

“…BCC-CSM2-MR, IPSL-CM6A-LR, MPI-ESM1-2-LR) show that deforestation can cause local summer warming over the deforested areas (figure 2), which is consistent with observational findings (figure S5). In contrast, some other models exhibit summer cooling in the temperate regions (figure 2), which may be due to the indirect effects of clouds or additional contributions of roughness length change to surface temperature in models (Devaraju et al 2018, Liu et al 2023.…”

Local and Nonlocal Biophysical Effects of Historical Land Use and Land Cover Changes in CMIP6 Models and the Intermodel Uncertainty

“…First, we examined the effects of realistic LULCCs rather than idealized LULCCs (Chen et al, 2022; et al, 2017a, 2019). Second, our method treats the nonlocal effects as the difference between the total and local effects, allowing us to fully capture the atmospheric and oceanic feedbacks of LULCCs (Devaraju et al, 2018;Liu, Hua et al, 2023). Additionally, our method can be readily applied to existing CMIP6 outputs, which reduces the computational cost that is needed for additional simulations (De Hertog et al, 2022;Li, Chen, et al, 2023).…”

“…Therefore, intermodel differences in the nonlocal effects can be largely attributed to divergent nonlocal changes in LW↓ and SH. Meanwhile, different simulations of atmospheric and oceanic feedbacks may also play an important role (Liu, Hua et al, 2023). At the regional scale, the sources of intermodel differences in the nonlocal effects differ among regions.…”

“…LULCCs, on the other hand, can indirectly influence the surface temperature of neighboring or remote regions via changes in cloud formation or even large-scale atmospheric circulations (Cerasoli et al, 2021;Laguë et al, 2019;Portmann et al, 2022). Such effects are referred to as nonlocal effects (Winckler et al, 2017a) and are widely acknowledged to be nonnegligible (Chen & Dirmeyer, 2020;Liu, Hua et al, 2023;Winckler et al, 2019). More importantly, the nonlocal effects of LULCCs may be quite different from the local effects in sign and magnitude (Chen & Dirmeyer, 2020;Hua et al, 2023;Santos et al, 2023).…”

“…Another way is based on the decomposition method of the surface energy balance, such as the intrinsic biophysical mechanism (Devaraju et al, 2018;Li, Chen, et al, 2023;Liu, Hua et al, 2023). Nonetheless, the decomposition method uses changes in near-surface air temperature caused by LULCCs to represent atmospheric feedbacks from LULCCs, which probably cannot fully capture the nonlocal effects of LULCCs (Liu, Hua et al, 2023). As such, how realistic LULCCs influence climate through local and nonlocal processes remains inadequately examined.…”