Food for Thought: Crop Yields in the Columbia River Basin in an Altered Future.

Global population and food consumption growth in the next 40 years is expected to result in a doubling of the agricultural demand in the 2050s. Understanding the factors that affect crop yield potential is central to meeting the food security challenge. The relationships between these factors can be non-linear, non-monotonic, competing and crop specific with regional differences. This leads to potential for a change in the sign of the net crop yield response over time. In terms of adaptation this becomes important because it makes a system with a positive outlook in the near term more vulnerable to insufficient adaptation times further in the future.

The objective of this work is to characterize how the net response of crop yield potential to temperature and CO₂level increases in the Columbia River basin changes at multiple future time-scales. We look for potential for a shift in the sign of the net response over time and how this varies by crop type and location. We also explore how changes in planting dates and crop type/variety can help farmers to adapt.

Results for winter wheat and potatoes, both of which are economically important crops in the region, indicate that the net crop response has potential to switch signs over time, due to changes in the dominant effect. For alfalfa, the temperature effect on yields is non-monotonic, but the CO₂ effect dominates the temperature effect and the combined effect is monotonic. Adaptation to a corn cultivar that has a longer time to maturity could bring down net yield reductions from 30% to about 10%. For the climate regime in the Columbia River basin, agricultural production in the region has a general positive outlook  until various points  in the future which are crop and location- dependent.