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Title: Trend and uncertainty analysis of simulated climate change impacts with multiple GCMs and emission scenarios

Author
item Zhang, Xunchang
item LIU, W - Northwest Agricultural & Forestry University
item LI, Z - Northwest Agricultural & Forestry University
item CHEN, J - University Of Quebec

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2011
Publication Date: 6/1/2011
Citation: Zhang, X.J., Liu, W.Z., Li, Z., Chen, J. 2011. Trend and uncertainty analysis of simulated climate change impacts with multiple GCMs and emission scenarios. Agricultural and Forest Meteorology. 151(10):1297-1304.

Interpretive Summary: Knowledge of the potential impacts of climate changes on soil erosion is critical to natural resources conservation planning. The objective of this work was to evaluate the potential impacts of possible climate changes on soil erosion, surface runoff, and wheat productivity in central Oklahoma. Monthly projections for the period of 2010-2039 from the four general circulation models (global climate models) under the A2, B2, and GGa emissions scenarios (representing high, low, and intermediate emissions, respectively) were used. The Water Erosion Prediction Project (WEPP) model was run for each scenario under three tillage systems (conventional tillage, conservation tillage, and no-till). Compared with the present climate, it is virtually certain that mean precipitation during 2010-2039 will decrease by some 6%, daily precipitation variance increase by 12%, and maximum and minimum temperature increase by 1.46 and 1.26 degree in Celsius, respectively, near El Reno. In the same tillage systems, it is very likely that long-term soil water storage will decease, but runoff and soil loss will increase despite the projected decreases in precipitation. There will be no significant climate-related changes in wheat grain yield. The overall results indicate that conservation tillage and no-till systems should be effective in controlling soil erosion under projected climate changes in central Oklahoma. This work provided useful information to soil and natural resources conservationists for adjusting conservation practices in response to possible climate changes.

Technical Abstract: Impacts of climate change on hydrology, soil erosion, and wheat production during 2010-2039 at El Reno in central Oklahoma, USA, were simulated using the Water Erosion Prediction Project (WEPP) model. Projections from four GCMs (CCSR/NIES, CGCM2, CSIRO-Mk2, and HadCM3) under three emissions scenarios (A2, B2, and GGa) were selected. An explicit spatiotemporal downscaling method was used to downscale monthly projections at GCM grid boxes to daily weather series at the target location. A common regional cropping system (annual winter wheat) under three contrasting tillage systems (no-till, conservation, and conventional) was simulated. Compared with the present climate, overall t-tests, lumped over all GCMs and emission scenarios (n=12), show that it is virtually certain that mean precipitation will decrease by some 6% (>98.5% probability), daily precipitation variance will increase by 12% (>99%), and maximum and minimum temperature will increase by 1.46 and 1.26 °C (>99%), respectively, during 2010-2039 near El Reno. In the same tillage systems, it is very likely (>90%) that evapotranpiration and long-term soil water storage will decease, but runoff and soil loss will increase despite the projected decreases in precipitation. There will be no significant climate-related changes in wheat grain yield. Further analyses using paired t-tests show that daily precipitation variance projected under GGa is greater than those under A2 and B2 (P=0.1), resulting in much greater runoff and soil loss under GGa (P=0.1). HadCM3 projected greater mean annual precipitation than CGCM2 and CSIRO (P=0.1). Consequently, greater runoff, grain yield, transpiration, soil evaporation, and soil water storage were simulated for HadCM3 (P=0.1). The inconsistency among GCMs and differential impact responses between emission scenarios underscore the necessity of using multi-GCMs and multi-emission scenarios for reliable impact assessments. Overall results show that no-till and conservation tillage systems should be adopted for better soil and water conservation and environmental protection in the region under climate change.