Deposition of wildfire smoke on snow contributes to its darkening and accelerated snowmelt. Recent field studies have identified dark brown carbon (d-BrC) to contribute 50–75% of shortwave absorption in wildfire smoke. d-BrC is a distinct class of water-insoluble, light-absorbing organic carbon that co-exists in abundance with black carbon (BC) in snow across the world. However, the importance of d-BrC as a snow warming agent relative to BC remains unexplored. We address this gap using aerosol-snow radiative transfer calculations on datasets from laboratory and field measurement. We show d-BrC increases the annual mean snow radiative forcing between 0.6 and 17.9 W m⁻², corresponding to different wildfire smoke deposition scenarios. This is a 1.6 to 2.1-fold enhancement when compared with BC-only deposition on snow. This study suggests d-BrC is an important contributor to snowmelt in midlatitude glaciers, where ~40% of the world’s glacier surface area resides.

野火烟雾在雪上的沉积导致雪变黑并加速融雪。最近的实地研究发现，深棕色碳 (d-BrC) 占野火烟雾中 50-75% 的短波吸收率。 d-BrC 是一类独特的不溶于水、吸光的有机碳，与黑碳 (BC) 大量共存于世界各地的雪中。然而，d-BrC 作为雪加温剂相对于 BC 的重要性仍有待探索。我们通过对实验室和现场测量的数据集进行气溶胶-雪辐射传输计算来解决这一差距。我们发现 d-BrC 使年平均雪辐射强迫增加了 0.6 至 17.9 W m ^{− 2} ，这对应于不同的野火烟雾沉积情景。与雪上仅沉积 BC 相比，这是 1.6 至 2.1 倍的增强。这项研究表明，d-BrC 是中纬度冰川融雪的重要贡献者，世界上约 40% 的冰川表面积位于该地区。