By Lauren Parker, University of California, Davis (formerly University of Idaho)
From Washington apple orchards to Oregon blueberry fields and Idaho’s burgeoning vineyards, the Northwest is well-known for its agricultural abundance (Figure 1). Specialty crop production across the three states is a multi-billion dollar enterprise and, like virtually all agricultural systems across the region, will be challenged by climate change (Houston et al. 2018).
Climate change is also projected to impact California specialty crop production (Lobell et al. 2006), lowering yields of some crops and perhaps entirely eliminating the production of others. As warming temperatures reshape where the climate is suitable for perennial crops in California, some specialty crop growers in cooler regions like the Northwest may benefit.
Over the coming decades, the Northwest is projected to see warmer winters, longer growing seasons, and more growing degree days each year. These changes could mean once-too-cool Northwest farmlands will be suitable for growing warmer-climate crops. However, warmer temperatures may pose their own challenges for cool-climate specialty crops already in place, including driving changes in when crops need water and how much.
In order to assess how climate change may shift where the climate is suitable for growing specialty crops in the coming decades, Dr. John Abatzoglou and I developed climate suitability models for five perennial specialty crops: almonds, apples, blueberries, cherries, and grapes. Katherine Hegewisch, our team’s webtool developer, then created interactive web-based tools to visualize and explore the model results. This work, which builds on research we discussed in an earlier article, tracks whether temperature conditions are suitable for crop cultivation over the coming decades and identifies the potential factors – such as frost damage – limiting successful production. Because the suitability models rely on tracking crop development throughout the year, the timing of key crop phases like flowering and maturation can also be tracked and reported (Figure 2).
Temperatures aren’t the only determining factor driving where certain crops are grown; water is another critical component to crop cultivation, particularly for perennial crops that need water year round and cannot easily be fallowed or easily replaced with drought-tolerant varieties. Most perennial crop growers in the Northwest rely on irrigation to satisfy their crops’ water demands. In order to help growers identify whether they may have enough water to meet crop needs under future climate conditions, we also modeled crop water demand relative to water availability from precipitation and soil moisture in order to estimate just how much of a crop’s annual water needs would have to be met with irrigation (Figure 3).
The results from the modeling efforts for the five specialty crops we examined are largely positive for Northwest growers. Warmer temperatures may allow for the geographic expansion of these specialty crops across the region. Almonds may thrive along the Snake River south of Nampa, ID in the coming decades thanks to less frost damage, while Cabernet Sauvignon may expand as far north as the Okanagan Valley of north-central Washington owing to longer and warmer summers.
Warmer temperatures and drier summers may also raise irrigation water needs, and total irrigation water demands may increase by approximately 10-25% by the 2050s, depending on crop and location. Though this may be a challenge in drier years or in more arid regions, irrigation management strategies could provide means to mitigate for increased water demands while maintaining agricultural productivity.
As climate change continues to pressure agricultural production, these model results showing future crop suitability, development timing, and irrigation water needs can serve as tools in the agricultural industry’s toolbox when considering future crops and investments in the region.
Please check out a recording of a webinar we recently gave that details a suite of web tools for agricultural decision makers, including the crop suitability tools. For more information on the model specifics, visit Climate Toolbox: Future Crop Suitability and check out the information available under the Documentation tab.
References
Houston, L., Capalbo, S., Seavert, C., Dalton, M., Bryla, D. and Sagili, R., 2018. Specialty fruit production in the Pacific Northwest: adaptation strategies for a changing climate. Climatic change, 146(1-2), pp.159-171. Online Access
Lobell, D.B., Field, C.B., Cahill, K.N. and Bonfils, C., 2006. Impacts of future climate change on California perennial crop yields: Model projections with climate and crop uncertainties. Agricultural and Forest Meteorology, 141(2-4), pp.208-218. Online Access
Comments
Once the model is working other crops can be introduced. So, what happens if we plant 50 trees per hectare in the Northwest? On the edges of the fields, and including agroforestry.
Will this change local climate and precipitation?
Hi Pieter,
The temperature and precipitation data that we used were from downscaled global climate models, so we don’t have the capacity to quantify in this exercise what those sorts of land use changes might mean for local climates. Also it’s important to note that the spatial resolution of these modeled data are at 4-km — so we are certainly not capturing field-scale variations in temperature (ie microclimates) that could allow for (or preclude) crop production. That is, field-scale reality may vary from the model results because of the resolution of the input climate data. However, the regional patterns of change are in line with what we expect and this model exercise provides some quantitative measure of that change and what climatic conditions may be driving it. That all said, I would expect that land use change (e.g. planting trees along the edges of farm fields) has the capacity to alter the field-scale or sub-field scale microclimates. What that could mean for crop suitability though, I’m afraid I can’t say.
Thanks for your interest!