Divergent urban vegetation inequality in Northern and Sunbelt United States cities under climate extreme events

Abstract Urban vegetation inequality (UVI) undermines the equitable distribution of ecosystem services such as heat mitigation. However, the role of climate variability in shaping UVI remains unclear. Here we have developed a methodology using satellite, census, and climate data to analyze UVI across 245 major U.S. cities. Our study proposed a vegetation polarization index (VPI), calculated as the normalized difference between the 90th and 10th percentiles of NDVI, to measure UVI. We examined how climate events affect UVI differently in the Sunbelt versus northern cities. Sunbelt cities display exacerbated UVI under drought and warmer climates, while colder and wetter conditions may increase UVI in northern cities. Hot droughts can amplify UVI across almost all cities, with Sunbelt cities showing greater vulnerability. We analyzed UVI trends from 2001 to 2020, revealing that Sunbelt cities exhibit worsening UVI trends, while northern cities show improving trends. These changes are related to climate shifts and socioeconomic factors, underscoring the vulnerability of U.S. cities to fluctuating UVI under climate change. Socioeconomic conditions play a significant role in exacerbating this vulnerability.