Satellite observations of eastern North America show that plants in and around urban areas bud earlier in the spring and retain their foliage later in the fall than do plants in nearby rural settings. Although that trend had been noted before, the new data suggest the differences are at least partially due to the phenomenon dubbed the "urban heat island." Cities retain enough heat to raise their temperatures above those in surrounding regions.
Most studies of increasing temperatures have examined global warming over recent decades. It has disrupted biological life cycles worldwide, triggering earl