Adaptation Strategies for Agricultural Sustainability in Yolo County, California

This place‐based case study in an agricultural county in California’s Central Valley focused on
the period of 2010–2050, and dealt with biophysical and socioeconomic issues related to both
mitigation of greenhouse gas (GHG) emissions and to adaptation to an uncertain climate. In the
past 100 years, changes in crop acreage has been more related to crop price and availability of
irrigation water than to growing degree days during summer, and in fact, summer
temperatures have increased less than winter temperatures. Econometric analysis indicated that
warmer winters, as projected by Geophysical Fluid Dynamics Laboratory‐Bias Corrected
Constructed Analog during 2035–2050, could result in less wheat acreage, more alfalfa and
tomato acreage, and slight effects on tree and vine crops. The Water Evaluation and Planning
(WEAP) model showed that these econometric projections did not reduce irrigation demand
under either the B1 or A2 scenarios, but a diverse, water‐efficient cropping pattern combined
with improved irrigation technology reduced demand to 12 percent below the historic mean.
Collaboration during development of Yolo County’s Climate Action Plan showed that nitrous
oxide (mainly from nitrogen fertilizers) was the main source (≅40 percent) of agricultural
emissions. Emissions from cropland and rangeland were several orders of magnitude lower
than urbanized land per unit area. A survey distributed to 570 farmers and ranchers achieved a
34 percent response rate. Farmers concerned about climate change were more likely to
implement water conservation practices, and adopt voluntary GHG mitigation practices. Use of
the urban growth model (UPlan) showed that channeling much or all future urban
development into existing urban areas will increase ecosystem services by preserving
agricultural land and open space, immensely reducing the Yolo County’s GHG emissions, and
greatly enhancing agricultural sustainability.