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Black-carbon reduction of snow albedo


Climate models indicate that the reduction of surface albedo caused by black-carbon contamination of snow contributes to global warming and near-worldwide melting of ice1,2. In this study, we generated and characterized pure and black-carbon-laden snow in the laboratory and verified that black-carbon contamination appreciably reduces snow albedo at levels that have been found in natural settings1,3,4. Increasing the size of snow grains in our experiments decreased snow albedo and amplified the radiative perturbation of black carbon, which justifies the aging-related positive feedbacks that are included in climate models. Moreover, our data provide an extensive verification of the Snow, Ice and Aerosol Radiation model1, which will be included in the next assessment of the Intergovernmental Panel on Climate Change5.

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Figure 1: Spectral albedo of snow of different Reff measured in our experiments (dots) and modelled using SNICAR (shaded bands).
Figure 2: Spectrally weighted snow albedo over the 300–2,500 nm solar spectrum: derived from our experiments (dots, ±1 standard deviation) and modelled using SNICAR (shaded bands).
Figure 3: Snow-albedo reduction attributed to BC computed as the albedo of pure snow minus the albedo of BC-contaminated snow for a 0° solar zenith angle (unless otherwise noted).


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This research was financially supported by the Public Interest Energy Research programme of the California Energy Commission and the Atmospheric Systems Research programme of the Department of Energy, Office of Biological and Environmental Research. O.L.H. received financial support from the E.O. Lawrence Fellowship at Lawrence Berkeley National Laboratory. We thank M. Flanner for providing an executable version of the SNICAR model online and modifying it to accommodate our analysis, C. Preble for assistance in our laboratory and T. Novakov for more than a decade of encouragement.

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O.L.H. conducted the experiments, ran the model simulations and analysed the data with guidance from T.W.K. O.L.H. and T.W.K. designed the experiments and co-wrote the manuscript.

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Correspondence to Odelle L. Hadley.

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The authors declare no competing financial interests.

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Hadley, O., Kirchstetter, T. Black-carbon reduction of snow albedo. Nature Clim Change 2, 437–440 (2012).

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