University of Idaho - I Banner
A student works at a computer


U of I's web-based retention and advising tool provides an efficient way to guide and support students on their road to graduation. Login to VandalStar.

U of I Study: Climate Models Predict Almond Harvest Expansion to Oregon

January 05, 2018

Oregon almonds may replace their counterparts from California on grocery store shelves by the 2050s, according to a study of climate models published by University of Idaho researchers in the journal Climatic Change.

The study, “Shifts in the Thermal Niche of Almond Under Climate Change,” was funded by the USDA Northwest Climate Hub and Regional Approaches to Climate Change (REACCH), a U.S. Department of Agriculture National Institute of Food and Agriculture project led by U of I.

U of I researchers Lauren Parker, lead author on the study, and geography Associate Professor John Abatzoglou combined published field observations with temperature data from climate models to examine the timing of almond growth and development and to predict the potential suitability of almond cultivation from California to Washington state over the next half-century.

Temperature is one of the driving climate factors governing where crops can be successfully cultivated — and cool temperatures are just as important as warm temperatures when it comes to growing tree crops like almonds. In the winter, Parker said almonds require sufficient exposure to cool temperatures. In spring and summer, warm temperatures are needed for flower, leaf and fruit development. Once the tree has begun its development in spring, damaging frosty temperatures must be avoided. 

The researchers found that while the Central Valley of California, where more than 99 percent of U.S.-grown almonds are cultivated, will remain thermally suitable into the mid-21st century, the Willamette Valley of Oregon will also have temperatures suitable to growing almonds by 2050.

“This is primarily due to a reduction in the risk for spring frost damage and a warmer growing season,” said Parker, a postdoctoral fellow in geography in the College of Science. 

While warmer temperatures may allow for almond expansion into western Oregon the result in California’s almond country will be an earlier bloom and an earlier harvest as warmer weather speeds up flower and fruit development.

The authors caution, however, that suitable temperatures do not necessarily translate into successful cultivation. 

“One of the primary limitations to cultivation is water, which we did not account for in this study. As temperatures rise, the water demand of almond orchards will increase,” Parker said. “So, there may still be climate-related challenges for almond growers in the future.”

Increasing market demand for almonds has spurred a doubling of almond acreage in California over the past two decades, Parker said, with new plantations going in despite recent drought conditions. 

“Almond growers are very adept at using their water wisely, but it was with potential future water challenges in mind that we wanted to ask the question, at least from a temperature standpoint, ‘If we’re struggling to grow almonds in California in 30 years, will we be able to grow them anywhere else?’” Parker said.

Abatzoglou, the study’s co-author, said additional factors will drive the reality of whether almond cultivation will expand into Oregon.  

“While warming may change the geography of where crops, like almonds, can be successfully grown, logistical challenges like access to irrigation, harvesting facilities and the market demand will govern whether or not we see an expansion of almond orchards in the future,” Abatzoglou said. “Our goals as scientists are help identify both the impacts of climate change to existing farming systems as well as opportunities for agricultural systems to adapt to our changing climate.”

This latest paper follows previous almond-related studies by Parker and Abatzoglou that appeared in the journals Environmental Research Letters and International Journal of Biometeorology.

This study, “Shifts in the Thermal Niche of Almond Under Climate Change,” was funded as part of USDA National Institute of Food and Agriculture grant No. 2011-68002-30191 titled “PNW Regional Approaches to Climate Change.” The total amount of federal funds for the entire project is $20 million, which amounts to 100 percent of the total cost of the project. An additional $4,000 in funding for the study was provided by the USDA Northwest Climate Hub.

Media Contacts:
Lauren Parker
Applied Climate Science Lab, University of Idaho 

Brad Gary
University Communications & Marketing


About the University of Idaho

The University of Idaho, home of the Vandals, is Idaho’s land-grant, national research university. From its residential campus in Moscow, U of I serves the state of Idaho through educational centers in Boise, Coeur d’Alene and Idaho Falls, nine research and Extension centers, plus Extension offices in 42 counties. Home to nearly 12,000 students statewide, U of I is a leader in student-centered learning and excels at interdisciplinary research, service to businesses and communities, and in advancing diversity, citizenship and global outreach. U of I competes in the Big Sky and Western Athletic conferences. Learn more at