资源环境科技发展态势分析平台

The 100^th meridian is a conceptual arid‐humid divide that effectively bisects the continent of the United States into the humid east and arid west. Here, we examine the historical and future shifts of the 100^th meridian from atmospheric, hydrologic and agro‐ecological perspectives. We find that the effective arid‐humid divide regarding vegetation greenness and runoff have been moving toward west with a mean shift of 0.73^o (1982‐2015) and 2.08^o (1961‐2010), respectively, suggesting decreased agro‐ecological and hydrologic aridity in the region. For future periods, the agro‐ecological divide shows a persistent westward movement, whereas eastward shifts of the 100^th meridian are detected from the atmospheric and hydrologic perspectives. Nevertheless, the eastward movements of the atmospheric and hydrologic divide substantially slow down when the vegetation response to elevated atmospheric CO₂ is accounted for. This finding demonstrates that CO₂ fertilization on vegetation could largely alleviate the warming‐induced drying tendency around the 100^th meridian region.