Background

A suitability model for growing hybrid poplar was previously developed for the Advanced Hardwood Biofuels Northwest (AHBNW) research program. Suitability was determined by nine variables, including average monthly high temperature, total monthly precipitation, and growing season length. These are likely to change over the next 100 years due to climate change.

Predicted future values were obtained from the Climate Wizard, an online tool developed by The Nature Conservancy, the University of Washington, and the University of Southern Mississippi (www.climatewizard.org), using the GFDL-CM2.1 global circulation model and A2 (High) IPCC greenhouse gas concentration scenario.

Our Work

The suitability model developed for the AHBNW project is based on poplar research and uses the Analytic Hierarchy/Network Process method. Each factor receives a score between 0 and 1. Factors are weighted according to relative importance to each other and summed. Models were developed with and without irrigation. ‘With Irrigation’ removed the total monthly precipitation factor and reweighted the remaining factors. The model was analyzed using 256 by 256 meter grid cells.

Temperature, precipitation, and growing season length inputs were replaced with predicted values from the climate change model developed by the U.S. Department of Commerce and the NOAA Geophysical Fluid Dynamics Laboratory (GDPL CM2.1). The A2 (High) carbon emissions scenario developed by the IPCC was assumed. Projected temperature and precipitation data are available at .5 by .5 degree cells and for two time periods (2046-2065 and 2081-2100).

Results

Future climate is expected to be hotter and drier over much of the western United States. Monthly average high temperatures above 85 degrees and total precipitation below 1 inch are only marginally suitable for hybrid poplar. Results show decreased suitability for hybrid poplar across the majority of the western United States.

Irrigation moves a large number of acres from Moderately to Highly suitable. With climate change, many acres transition back to Moderately suitable. Without irrigation, many Moderately suitable acres become Marginally suitable. Irrigation mitigates draught conditions under current and future scenarios, but water availability may also be impacted by climate change, and irrigation may not be feasible everywhere.

Deliverables