Projections of leaf area index in earth system models

Journal Article · Wed Mar 09 00:00:00 EST 2016 · Earth System Dynamics (Online)

DOI:https://doi.org/10.5194/esd-7-211-2016· OSTI ID:1268151

Mahowald, Natalie ^[1]; Lo, Fiona ^[1]; Zheng, Yun ^[1]; Harrison, Laura ^[2]; Funk, Chris ^[2]; Lombardozzi, Danica ^[3]; Goodale, Christine ^[4]

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1. Cornell Univ., Ithaca, NY (United States). Dept. of Earth and Atmospheric Sciences
2. Univ. of California at Santa Barbara, Santa Barbara, CA (United States). Dept. of Geography
3. National Center for Atmospheric Research, Boulder, CO (United States) Climate and Global Dynamics Division
4. Cornell Univ., Ithaca, NY (United States). Dept. of Ecology and Evolutionary Biology

The area of leaves in the plant canopy, measured as leaf area index (LAI), modulates key land–atmosphere interactions, including the exchange of energy, moisture, carbon dioxide (CO₂), and other trace gases and aerosols, and is therefore an essential variable in predicting terrestrial carbon, water, and energy fluxes. Here our goal is to characterize the LAI projections from the latest generation of earth system models (ESMs) for the Representative Concentration Pathway (RCP) 8.5 and RCP4.5 scenarios. On average, the models project increases in LAI in both RCP8.5 and RCP4.5 over most of the globe, but also show decreases in some parts of the tropics. Because of projected increases in variability, there are also more frequent periods of low LAI across broad regions of the tropics. Projections of LAI changes varied greatly among models: some models project very modest changes, while others project large changes, usually increases. Modeled LAI typically increases with modeled warming in the high latitudes, but often decreases with increasing local warming in the tropics. The models with the most skill in simulating current LAI in the tropics relative to satellite observations tend to project smaller increases in LAI in the tropics in the future compared to the average of all the models. Using LAI projections to identify regions that may be vulnerable to climate change presents a slightly different picture than using precipitation projections, suggesting LAI may be an additional useful tool for understanding climate change impacts. Going forward, users of LAI projections from the CMIP5 ESMs evaluated here should be aware that model outputs do not exhibit clear-cut relationships to vegetation carbon and precipitation. Lastly, our findings underscore the need for more attention to LAI projections, in terms of understanding the drivers of projected changes and improvements to model skill.

• Research Organization: Cornell Univ., Ithaca, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER); US Agency for International Development (USAID) through Broadening Access and Strengthening Input Market Systems Collaborative Research Support Program (BASIS AMA CRSP)
• OSTI ID: 1268151
• Journal Information: Earth System Dynamics (Online), Vol. 7, Issue 1; ISSN 2190-4987
• Publisher: European Geosciences Union
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
general-circulation model
carbon cycle feedback
land-surface models
ndvi time-series
climate-change
part i
interannual variability
coupled model
terrestrial
vegetation