Lawrence Berkeley National Laboratory

Abstract Anthropogenic heat emissions from human energy consumption contribute to the urban heat island (UHI) effect, yet their spatiotemporal distributions and impacts remain uncertain. In this study, we develop a 100 m resolution, hourly anthropogenic heat flux (AHF) data set for Los Angeles County and use the Weather Research and Forecasting model to quantify the meteorological impacts of AHF and the heat mitigation potential of electrification and energy efficiency measures. Annual mean AHF across the county was 2.54 W m −2 , increasing to 9.65 W m −2 over urban areas, with substantial variability across both space and time. AHF increased urban mean 2 m air temperature by approximately ∼0.3°C and canopy air temperature by more than 1°C, with localized canopy warming exceeding 4°C in certain neighborhoods. Electrification and energy efficiency measures can substantially mitigate warming caused by AHF, with stronger cooling effects near highways. Under the most aggressive mitigation scenario, these measures offset more than 50% of the AHF‐induced warming in both mean 2 m air temperature and canopy air temperature across urban Los Angeles. This study confirms AHF as an important contributor to Los Angeles' UHI and demonstrates that energy‐use reductions can provide non‐trivial cooling benefits. More broadly, this study highlights the value of coupling high‐resolution AHF inventories and meteorological modeling to improve effective heat mitigation planning under future urbanization and climate change. Plain Language Summary Energy consumption from buildings, transportation, and even human metabolism adds extra heat to cities. We call this anthropogenic heat. Anthropogenic heat contributes to the urban heat island effect, describing a common phenomenon where cities are generally warmer than surrounding rural or suburban areas. In this study, we mapped anthropogenic heat across Los Angeles, showing how it varies by neighborhood and time of day. Using computational weather simulations, we found that this anthropogenic heat noticeably raises air temperatures, with some neighborhoods experiencing much larger temperature increases than others. We also show that electrification and energy efficiency measures, like improving building efficiency and transitions to more electric vehicle use, lead to less anthropogenic heat and subsequently lower urban air temperatures. These results show that human activity is a major contributor to urban heat and that energy use reductions can provide meaningful heat mitigation co‐benefits. Mapping heat at finer scales helps city planners and policymakers identify where and when actions will have the greatest impact, supporting strategies to make cities cooler, more comfortable, and more resilient to extreme heat. Key Points A high‐resolution (100 m) hourly anthropogenic heat (AH) data set is developed for Los Angeles (LA) County, California AH increases 2 m air temperature () by 0.27°C and urban canopy air temperature () by 1.17°C in urban LA during the summer Intensive electrification and energy efficiency measures are estimated to reduce mean urban and by 0.16°C and 0.65°C, respectively