Radiative Forcing Assessment of Black Carbon in Snow from the Antarctic Peninsula 

Abstract

The pristine Antarctic environment, despite its remoteness, is not immune to the influence of anthropogenicpollutants. This study focuses on quantifying the Radiative Forcing (RF) resulting from Black Carbon (BC)concentrations in snow samples collected from various points on the Antarctic Peninsula during the austral summerof 2023, aiming to assess the impact of BC on the snowpack albedo and, consequently, on the regional climate. To thebest of our knowledge, in most of the locations studied, BC concentrations in snow have never been measured before.Snow samples were meticulously collected from different locations on the Antarctic Peninsula, covering a diverserange of environments, including base surroundings, remote locations, and icebergs. This effort was undertaken aspart of the ECA59 campaign, funded by the Chilean Antarctic Institute (INACH). The sampling constituted the initialphase of a project involving three distinct sampling periods. Specifically, the collection sites were situated in theeastern sector of the peninsula, known for its minimal human presence and limited prior research, making it arelatively unexplored region. BC concentrations in our snow samples were measured following the method describedin Cereceda-Balic et al. (2022, https://doi.org/10.1016/j.envres.2022.113756). To understand the BC RF, the SNICAR(SNow, ICe, and Aerosol Radiation) model was employed to simulate snow albedo for measured BC concentrations.This methodology allowed for an assessment of the potential BC-induced changes in albedo and the resulting RF. Theanalysis revealed a significant range of BC concentrations in Antarctic snow samples, spanning from 2.4 to 1157 ng g-1. Simulating snow albedo using the SNICAR model indicated BC-induced albedo reductions of up to 20% relative to clean snow. The calculated BC-induced RF reached up to 38 W m-2, indicating a substantial climatic impact of BC in the Antarctic Peninsula region. Our findings underscore the influence of BC on the radiative properties of snow in the Antarctic Peninsula. The diverseBC concentrations observed here suggest varying sources and highlight the need for continued monitoring. The resultsreveal the vulnerability of the Antarctic Peninsula to the impacts of anthropogenic pollutants, even in its seeminglypristine surroundings. Acknowledging and addressing these influences is essential for assessing the broaderimplications of climate change in polar regions. Continued research at these little-explored sites is crucial for refiningclimate models and informing mitigation strategies to preserve the integrity of the Antarctic environment. Acknowledgments: INACH Project RT_34-21, and ANID Project: Fondecyt Projects N°1221526 andN°11220525, ANILLO ACONCAGUA N°ACT210021, and FOVI230167