<p>We estimated the black carbon (BC) concentration over the Hindu Kush Himalayan region (HKH), its impact on snow-albedo reduction and sensitivity on annual glacier runoff over the identified glaciers. These estimates were based on free-running aerosol simulations (<i>freesimu</i>) and constrained aerosol simulations (<i>constrsimu</i>) from an atmospheric general circulation model, combined with numerical simulations of glacial mass balance model. BC concentration estimated from <i>freesimu</i> performed better over higher altitude (HA) HKH stations than that over lower altitude (LA) stations. The estimates from <i>constrsimu</i> mirrored well the measurements when implemented for LA stations. Estimates of the spatial distribution of BC concentration in the snowpack (<i>BC</i><sub><i>c</i></sub>) over the HKH region led to identifying a hot-spot zone located around Manora peak. Among glaciers over this zone, <i>BC</i><sub><i>c</i></sub> (> 60 μg kg<sup>−1</sup>) and BC-induced snow-albedo reduction (≈ 5 %) were estimated explicitly being high during the pre-monsoon for Pindari, Poting, Chorabari, and Gangotri glaciers (which are major sources of fresh water for the Indian sub-continent). The rate of increase of <i>BC</i><sub><i>c</i></sub> in recent years (i.e. over the period 1961–2010) was, however, estimated being the highest for the Zemmu glacier. Sensitivity analysis with glacial mass balance model indicated the increase in annual runoff from debris-free glacier area due to BC-induced snow albedo reduction (SAR) corresponding to <i>BC</i><sub><i>c</i></sub> estimated for the HKH glaciers was 4 %–18 %, with the highest being for the Milam and Pindari glacier. The rate of increase in annual glacier runoff per unit BC-induced percentage SAR was specifically high for Milam, Pindari, and Shunkalpa glacier. The source-specific contribution to atmospheric BC aerosols by emission sources led to identifying the potential emission source being primarily from the biofuel combustion in the Indo-Gangetic plain south to 30° N, but also from open burning in a more remote region north to 30° N.</p>