Science / Medicine : Palm Springs Cools, Thanks to Irrigation

Unlike most other cities in the United States, Palm Springs has actually become cooler during the last 15 years, researchers said last week. Climatologist Robert Balling of Arizona State University at Tempe said that the average daily temperature in Palm Springs, relative to the surrounding desert, has actually dropped 2 to 3 degrees Fahrenheit since the mid-1970s.

Balling attributed the drop to the increasing construction of golf courses and the more widespread use of irrigation in the Palm Springs area. The irrigated land absorbs less heat during the day and cools off faster at night. The temperature drop is in sharp contrast to other cities, where temperatures have been increasing because of the so-called “urban heat island” effect.

In most cities, asphalt and concrete absorb heat and take a long time to cool. Glass increases heat by reflecting it, and internal combustion engines heat the air. Balling noted that the nighttime temperature in Phoenix, for example, has increased 7 degrees in the past 40 years.