Comparison of plant hardiness zone maps for 1990 and 2006 offers evidence that GCC is occurring (Figure 1). As demonstrated in the maps, the zones have generally moved orth, indicating broad warming trend in the United States. For North Carolina, the dominant zone in 1990 (ie, zone 7) was, by 2006, superseded by the next warmest zone (ie, zone 8). Concurrently, the colder zone 6 contracted, and the warmer zone 9 made its first appearance on the state’s eastern shores. In 16 years, then, the state became warmer from the beaches, through the Piedmont, and across the mountains.