Rising temperatures appear to be reducing the number of hours tree crops in the San Joaquin Valley are subjected to chill during the winter, a critical factor in producing a profitable yield, reported Ezra David Romero on Valley Public Radio, KVPR-FM.

Pistachios, for example, require temperatures between 32 and 45 degrees for about 700 hours each winter, but for the past four years have had less than 500 chill hours.

UC Davis researcher Hyunok Lee recently published a study about climate change impacts on agriculture in UC Agriculture and Natural Resources' peer-reviewed journal