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Studies suggest a consistent drop in chill hours could edge out walnuts, pistachios.

Logan Hawkes 1, Contributing Writer

July 31, 2019

4 Min Read
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A tractor sits idle on a hot afternoon on a farm near Chico, Calif., in June 2018.Tim Hearden

Global warming or not, when the weather changes, farmers are often challenged to adjust the way they farm.

During extended periods of dry, hot weather or drought farmers often change their irrigation schedules or switch to drought-resistant varieties of their crop of choice. Others may switch the type of crops they plant to types that require less water and thrive in warmer climates.

When substantial or heavy rains arrive and crops struggle to emerge and prosper while unwanted weeds thrive, especially glyphosate-resistant varieties, farmers may change to fungicides with different modes of action. Similarly, when erosion strikes or nutrient loss in soils become a major concern, farmers often change tilling practices or turn to cover crops as a possible solution.

As the weather and climate changes in California, Central Valley farmers are learning there are several tools and methods available to help mitigate the challenges that arise.

Those challenges may include warmer or colder seasons or extended hot and dry summers, a delayed spring season, wetter or drier periods including flood or wildfire events, a lack of groundwater recharge or even frosty winters that can stretch well into the planting season.

These type of changes and others can cause many problems including delayed planting and late emergence of crops. In the orchard, problems may include late fall or early spring freeze damage or delayed bloom and leaf-out. During years with warmer temperatures, chill hours can be reduced.

In fact, a 2009 study conducted by researchers from the University of California, Davis used hourly and daily temperature records from 1950 to the end of the last century to determine winter chill in the Golden State had declined substantially during that period, by up to 30 percent in some regions of the state.

In a similar study conducted in 2007, the Intergovernmental Panel on Climate Change Fourth Assessment Report projected winter chill since 1950 through the middle of this century (2050) will decline by as much as 60 percent overall, and by the end of the 21st century the Central Valley of California may no longer be suitable for growing walnuts and pistachios as well as various types of fruit and nut crops.

Regardless what you farm or whether you operate livestock, dairy or poultry operations in California, changing weather and the larger influence of a changing environment has and will continue to impact the agricultural industry and the way we farm. And it’s not just California. The problem is a global issue.

From sporadic colder winters in some areas to diminishing polar caps, extensive droughts to deadly flooding and rising temperatures, weather and a changing climate, regardless how we label it and regardless the cause or duration, is a challenge around the world.

World changes and their impact

In California, several recent major events are a reminder of how quickly things can change. In just a matter of months the Golden State has gone from one of its worst droughts in state history to a historic wildfire disaster followed by historic rainfalls and flooding. Within a short period of time these disasters were followed by a significant round of earthquakes and tremors that remind us how fragile life can be.

While a series of events like those can be coincidence or something else, when we look at the number of major global incidents, we begin to see what may represent a pattern of change. According to a 2005 study, the total natural disasters reported each year has steadily increased, from 78 in 1970 to 348 in 2004. These disasters included earthquakes, droughts, wildfires, hurricanes, typhoons, floods, and tsunamis, according to U.S. Foreign Disaster Assistance (OFDA), a federal agency under the oversight of the United States Agency for International Development (USAID).

While the number of disasters has both fallen and risen in more recent years, many scientists around the world point to the overall increases in natural disasters as evidence of natural earth changes. Combined with an ever-increasing population base that has spread out from urban to more rural areas, more people are being adversely affected by these disaster events.

 The changing earth and its risk for agriculture

While farmers around the world are having to deal with weather and climate changes and natural disasters, California agriculture may be some of the hardest hit. The primary reason is because in many respects, California remains the breadbasket of the world.

Mitigating changes in the elements that affect farming and ranching in California is a growing challenge, but new programs are emerging and expanding to help fight those changes and how they may be easier to weather.

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