Nearly all energy used for human purposes is dissipated as heat within Earth's land-atmosphere system. Thermal energy released from non-renewable sources is therefore a climate forcing term. Averaged globally, this forcing is only +0.028 W m??, but over the continental United States and western Europe, it is +0.39 and +0.68 W m??, respectively. Here, present and future global inventories of anthropogenic heat flux (AHF) are developed, and parameterizations derived for seasonal and diurnal flux cycles. Equilibrium climate experiments show statistically-significant continental-scale surface warming (0.4-0.9?C) produced by one 2100 AHF scenario, but not by current or 2040 estimates. However, significant increases in annual-mean temperature and planetary boundary layer (PBL) height occur over gridcells where present-day AHF exceeds 3.0 W m??. PBL expansion leads to a slight, but significant increase in atmospheric residence time of aerosols emitted from large-AHF regions. Hence, AHF may influence regional climate projections and contemporary chemistry-climate studies.
