Almonds are everywhere these days. Fueled in part by a health food craze trumpeting the purported near-miraculous physiological (and even psychological) benefits of almonds, the tasty nut can now be bought raw, smoked, salted, and candied; turned into butter, milk, yogurt, and even ice cream (the latter having obvious psychological if dubious physiological benefits).
But just how much more almond enthusiasm can agricultural support? And what about climate? Are there limits to almond expansion?
These are some of the questions a study published in the International Journal of Biometeorology seeks to answer.
The study, conducted by Lauren Parker and her PhD advisor and CIRC researcher John Abatzoglou, examines where in California and the Southwestern United States new almond plantations are likely to be viable under current climate conditions. The researchers’ conclusion: the crop could soon come up against some real barriers to expansion.
To understand why this is so, let’s examine the almond growing map.
By far the world’s biggest almond producer is California. California orchards grow over 80 percent of almonds worldwide, translating into about $11 billion in annual revenue.
The reason for California’s virtual almond hegemony has a lot to do with the growing needs of the almond tree. Basically, there are three fundamental factors that limit where almond trees can grow: soil, water, and temperature. Let’s consider just the latter two: water and temperature.
Almonds take a lot of water to grow. As a consequence, most almond plantations are irrigated. When a particularly bad drought shows up, as it did recently for California and much of the American West, this reliance on irrigation is less than ideal. (We’ll circle back to this point.) On to temperature.
With temperature, almonds are a little like Goldilocks: temperatures must be just right.
Winter temperatures can’t be too cold because almonds have what’s called a limited cold hardiness, or a limited ability to tolerate cold temperatures. But like the picky fairy-tale heroine, almonds can’t have winter temperatures that are too warm either.
Almond trees have what are called chilling requirements, or a need for enough cold days each winter to signal to the almond tree that winter has both come and gone, and hence that it is now spring and safe to start growing again.
Spring temperatures must also be warm enough for almonds to flower. This is defined in the scientific literature as the number of springtime growing degree days. But wait…there’s more.
Almonds are also highly sensitive to frost damage; if temperatures drop below freezing in the springtime, almond production can take a big hit.
So, are there areas in the Southwest that meet all of these strict climatic requirements for almond orchards to expand? To answer that question, Parker and Abatzoglou used two types of computer models.
The first computer model simulated plant functions, accounting for how almonds physically respond to temperatures. The second model type identified where on a map of the Southwestern US (here defined as California, Nevada, and a sliver of western Arizona) almonds are currently planted, and looked for similar but currently unused climates across those states. By examining the results of the two models, the researchers were able to determine geographic regions throughout the Southwest that are thermally suitable for almond cultivation in today’s climate.
Under current climate conditions, both southern California and Nevada have sufficiently warm winters. However, the southern-most regions of both states fail to meet the tree’s chilling requirements. Go north and you find the opposite problem. Both northern California and northern Nevada lack enough springtime growing degree days for the tree to flower.
The take away: go too far north or too far south, and almonds are not a viable crop.
But by the far the most limiting temperature constraint was frost damage. Over one third of the land area in the Southwestern US has late spring freezes that can damage almond trees, making these areas unsuitable for new almond orchards.
Nonetheless, simulations from the models showed that 11 to 41 percent of Southwestern croplands where almonds are not currently grown are in fact suitable for almond cultivation. Areas identified to have just the right climatic conditions included California’s Central Valley and portions of southern California and Nevada, according to Parker and Abatzoglou.
However, while this work shows plenty of places where almonds are viable, there are plenty of barriers beyond climate that could prevent the crop from being growth in these places, the authors note. Let’s circle back to the big one: water.
Obviously, there must be enough water for the water-hungry almond orchards. And this could be a tall order in the American West with its long history of water disputes.
A less daunting obstacle to almond expansion is the simple fact that other crops currently occupy the almond Goldilocks zone. Consider Napa Valley. The valley would be an excellent place to grow almonds, according to Parker and Abatzoglou’s findings. Unfortunately for almonds, Napa Valley is already occupied by another high value crop—you guessed it, wine grapes. Then there’s still another factor limiting almond expansion: much of the viable growing spots simulated in the modeling are currently on federal and state lands or in areas where infrastructure for irrigation is lacking.
Parker and Abatzoglou conclude their paper by noting these limits, suggesting that these political and social limits along with almonds’ climate needs are likely to constrain the crop’s expansion. The researchers further suggest that existing almond orchards may need to rely on technological advances and increasing crop densities in order to keep up with the growing global demand for almonds in all their various incarnations.
Citation: Parker, Lauren E., and John T. Abatzoglou. “Comparing mechanistic and empirical approaches to modeling the thermal niche of almond.” International Journal of Biometeorology 1-14 (2017). DOI: 10.1007/s00484-017-1338-9
Linnia Hawkins is a Ph.D. candidate studying atmospheric science at Oregon State University. Working with the Oregon Climate Change Research Institute since 2014, Linnia’s research interests include, regional climate modeling and the impacts of climate change on forests in the western US. She is a regular contributor to The Climate CIRCulator.