Characterizing the warming effect of increasing temperatures on land surface: Temperature change, heat pattern dynamics and thermal sensitivity

Acute changes in temperature are projected to happen more frequently in cities in the future as induced by continued global warming and accelerated urbanization. However, studies dedicated to investigating the multifaceted warming effect of increasing temperatures on urban land surface are missing. This study explores the warming effect of different land covers in Shanghai with land surface temperatures (LST) increase from 6.4℃ to 37.9℃. The investigated warming effects cover aspects of temperature change, heat pattern dynamics and thermal sensitivity, which are quantified by a transition matrix, landscape metrics and a boosted regression tree (BRT) approach, respectively. The results obtained are mainly fourfold. First, both heat composition and configuration change with increase in LST. Second, vegetation exhibits large proportions of change between dominant temperature classes; construction has diversified temperature change directions; and water bodies show resistance to change under temperature increase. Third, the heat pattern is increasingly fragmented as the LST increases, and the change trends differ among land covers. Fourth, during four warming stages, the thermal sensitivity of construction, vegetation, and water bodies presents an increasing trend, a decreasing trend, and abrupt changes, respectively. These findings provide insight to inform thermal regulation measures in Shanghai, and improve our understanding of the warming effect of increasing temperatures on the land surface in a changing environment.