Temporal trends in biophysical temperature responses to actual land cover changes in northern mid-latitudes from 2006 to 2019

The biophysical effects of land cover change (LCC) on land surface temperature (LST) have garnered increasing attention. However, previous studies mainly focused on their spatial patterns, leaving temporal trends relatively underexplored. In this study, we selected the densely populated northern mid-latitudes region (NM, 20°N-50°N) as study area, and analyzed the temporal trends in biophysical temperature effects of LCC using long-term satellite observations. The key findings are as follows: (1) from 2006 to 2019, five dominant types of LCC were identified in the NM region, including conversion from barren land to grassland, grassland to barren land, cropland loss, urbanization, and cropland expansion; (2) although the net temperature effect of all LCCs during the study period was relatively small (0.003 K with a declining trend of -0.012 K/decade), this reflected the offsetting impacts of different LCC types, highlighting the importance of analyzing their distinct biophysical effects; (3) urbanization and cropland expansion were the LCCs with the most significant impacts on LST changes, with urbanization causing a continuous warming effect and cropland expansion consistently leading to cooling, which counteracted each other, resulting in minimal net warming across the region; and (4) The temperature impacts of both urbanization and cropland expansion exhibited a declining trend, primarily driven by non-radiative effects. In summary, this study provides a comprehensive analysis of the spatial distribution, temporal trends, and underlying mechanisms of LCC-driven temperature effects in the NM region, offering valuable insights for future land management policies.