Although cool winter temperatures are needed for perennials to accumulate chill, if temperatures dip below freezing during the wrong time of year, crops can be damaged. In California, citrus, avocados, and almonds are some of the more at-risk crops for frost damage, and they are also high-value crops. As subtropical trees, avocados and citrus are most cold-sensitive during mid-winter. Although almond trees are very hardy during winter, they are an early-blooming crop, and their tender flowers are quite cold-sensitive and may bud and bloom before the last spring frost has passed. In 2014, a December cold snap caused nearly $25-million in damages to California Navel oranges. Likewise, in February of 2018, a spring frost damaged more than $42-million worth of California almonds.

The Hub recently conducted a research study to assess how climate change may impact frost exposure for sensitive crops across the state. The results show that as winters and springs warm in the coming decades, the amount of frost exposure that growers must contend with will decline across the state.

The study also showed that for almonds, avocados, and oranges, the exposure to each crop's frost damage threshold temperature also declined, even during the crops' most at-risk month for frost damages. Fewer hours of frost exposure mean reduced risk of crop losses as well as reduced water and energy use for mitigation. In fact, simple estimates suggest that tens of thousands of acre feet of irrigation water and millions in energy costs for water pumping could be saved each year as the amount of time that protective measures are required is reduced.

Although it only takes one unmitigated cold snap to ruin a crop, and although frost will continue to be a challenge in the decades to come, reduced frost exposure is a small silver lining to the otherwise net negative impacts of climate change on California agriculture.

Read the full study for free through February 14th here.

California's forests play a critical role in providing ecosystem services such as fresh air, clean water, timber, and spaces for cultural and recreational opportunities. From the open, grassy hillsides of blue oak woodlands, to the park-like settings of ponderosa forests, to the damp and foggy groves of towering coastal redwoods, each forest type is unique and has its own climate stressors and management needs.

In partnership with the Science Advisory Panel of the California Governor’s Forest Management Task Force and the USGS Southwest Climate Adaptation Science Center, the USDA California Climate Hub recently published a series of briefs on healthy forests. Covering blue oak woodlands, ponderosa pine forests, and coastal redwood forests, these briefs communicate each ecosystems' general physical appearance, their myriad of ecological functions, and summarize the critical processes that contribute to keeping these forests and woodlands intact. We hope they help communicate example desirable conditions for managers' and private landowners' use.

The USDA will host a virtual Agriculture Outlook Forum February 18th and 19th. The event is open to the public and will feature a keynote address from the Secretary, as well as a session on wildfires in California and their implications for agriculture. Other session topics include agricultural markets and supply chains, managing risk, agricultural sustainability, innovation and technology, and commodity outlooks.

We encourage you to be in touch if we can be of service or assistance. Contact Hub Director Steve Ostoja and check out the California Climate Hub website for more information.

Have something you'd like us to share with our newsletter recipients? Know of a colleague who should be a part of our Spotlight series? Please let us know! Contact Hub Coordinator Lauren Parker.