Temperatures across the United States have been warming in recent decades, which may cause climate boundaries to shift in some areas. Discuss how to assess this situation

Answer 1

One way to assess the warming trend that has occurred over recent decades in the United States is to look at the temperatures needed for plants to grow and thrive. One of the main sources for farmers, gardeners, and landscapers in the U.S. is the plant hardiness map produced by the United States Department of Agriculture (USDA). This map places each part of the U.S. into one of 13 numerical zones, or hardiness zones, based on average annual minimum temperature (the coldest reading one might expect to observe in a typical year). The last few decades have shown shifts in the boundaries of the hardiness zones in the United States. Another important way to measure the risk posed by cold weather to plants is to look at the average dates of the first frost and freeze in autumn or the last frost and freeze in spring.