Greenhouse gas policy influences climate via direct effects of land-use change

Journal Article · Sat Jun 01 00:00:00 EDT 2013 · Journal of Climate, 26(11):3657-3670

DOI:https://doi.org/10.1175/JCLI-D-12-00377.1· OSTI ID:1083384

Jones, Andrew D.; Collins, William D.; Edmonds, James A.; Torn, Margaret S.; Janetos, Anthony C.; Calvin, Katherine V.; Thomson, Allison M.; Chini, Louise M.; Mao, Jiafu; Shi, Xiaoying; Thornton, Peter; Hurtt, George; Wise, Marshall A.

Proposed climate mitigation measures do not account for direct biophysical climate impacts of land-use change (LUC), nor do the stabilization targets modeled for the 5th Climate Model Intercomparison Project (CMIP5) Representative Concentration Pathways (RCPs). To examine the significance of such effects on global and regional patterns of climate change, a baseline and alternative scenario of future anthropogenic activity are simulated within the Integrated Earth System Model, which couples the Global Change Assessment Model, Global Land-use Model, and Community Earth System Model. The alternative scenario has high biofuel utilization and approximately 50% less global forest cover compared to the baseline, standard RCP4.5 scenario. Both scenarios stabilize radiative forcing from atmospheric constituents at 4.5 W/m2 by 2100. Thus, differences between their climate predictions quantify the biophysical effects of LUC. Offline radiative transfer and land model simulations are also utilized to identify forcing and feedback mechanisms driving the coupled response. Boreal deforestation is found to strongly influence climate due to increased albedo coupled with a regional-scale water vapor feedback. Globally, the alternative scenario yields a 21st century warming trend that is 0.5 °C cooler than baseline, driven by a 1 W/m2 mean decrease in radiative forcing that is distributed unevenly around the globe. Some regions are cooler in the alternative scenario than in 2005. These results demonstrate that neither climate change nor actual radiative forcing are uniquely related to atmospheric forcing targets such as those found in the RCP’s, but rather depend on particulars of the socioeconomic pathways followed to meet each target.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1083384
• Report Number(s): PNNL-SA-92027; KP1703020
• Journal Information: Journal of Climate, 26(11):3657-3670, Journal Name: Journal of Climate, 26(11):3657-3670
• Country of Publication: United States
• Language: English