Catchment land use shapes lake-atmosphere thermal contrast and synchrony globally

Lakes are integral components of the Earth system, regulating regional climate through exchanges of heat and moisture with the atmosphere. However, how catchment land use shapes lake-air thermal relationships at the global scale remains poorly understood. Here, we analyze 1036 large lakes (>100 km²) worldwide during 1992‒2020 to quantify changes in lake-atmosphere thermal contrast and synchrony, which we define, respectively, as the difference (T_diff) and sensitivity (T_sens) between lake surface water temperature and air temperature. Across lakes, T_diff declined in 79.0% of sites, while T_sens increased in 66.8%, indicating a widespread reduction in thermal contrast alongside strengthened lake-atmosphere synchrony. These trends varied systematically by basin type: the largest declines in T_diff occurred in grassland/barren-dominated basins (-0.12 °C (10 a)^-1), while increases in T_sens were significantly greater in forest- and grassland/barren-dominated basins than in cropland-dominated basins. Structural equation modeling shows that land use influences thermal contrast and synchrony both directly and indirectly through its effects on local climate, with the strongest total effects in grassland/barren-dominated basins (0.44), followed by forest-dominated (-0.28) and cropland-dominated basins (0.13). Our analysis suggests that greater land-use diversity can dampen trends in both thermal contrast and synchrony. Future projections suggest continued declines in T_diff and increases in T_sens throughout the 21st century, with land use modulating the magnitude of these changes. Together, these findings identify catchment land use as a critical yet underappreciated regulator of lake-atmosphere thermal dynamics and highlight the importance of integrating land-use considerations in lake management strategies.