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The Arctic is particularly vulnerable to the impacts of climate change, of which vessel-source black carbon aerosols serving as a prominent catalyst for these changes. This situation is poised to worsen as sea ice melts and shipping lanes change. Rapid action aimed at mitigating short-term climate forcing factors can yield almost immediate climate benefits in the Arctic. This article provides an overview of the legal framework governing black carbon in the Arctic, considering three distinct perspectives: the global, regional, and national dimensions. These perspectives encompass global forums represented by the International Maritime Organization (IMO) and the United Nations Framework Convention on Climate Change (UNFCCC), with a focus on recent developments concerning black carbon governance, notably the amendments to MARPOL Annex VI and Annex I. Regionally, forums represented by the Arctic Council and the European Union are examined. Black carbon emissions exhibit migratory characteristics, yet the primary legal responsibilities for emission reduction are concentrated within Arctic states. Therefore, this article also delves into the laws and practices of Arctic coastal states in their efforts to combat black carbon emissions, using Canada and Norway as examples. The analysis of institutional effectiveness in this article indicates that, at present, specialized legislation on black carbon is either vague or non-existent. The current Arctic ship-source black carbon governance system faces issues related to leadership ambiguity in its institutional structure, a limited scope of responsible entities, and a lack of diverse implementation measures. Simultaneously, the governance system is questioned for having weak or non-legally binding regulations at the level of legal enforcement. The article anticipates the introduction of more mandatory regulations while also encouraging the selection of non-coercive policy tools. Accordingly, this article argues that a coordinated governance system centered on IMO and the Arctic Council needs to be established. Such a framework should adopt a more inclusive approach to stimulate positive interactions between regulations, aiming to create a broader winning alliance based on the existing foundations. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the probability of black carbon (BC) transfer from high-intensity model forest fires in the taiga zone, determine the fields of concentrations and deposition of BC on the ice–snow surface, and assess the BC contribution to climate change in the Arctic. Model regions with the highest probability of large forest fires (the Komi Republic, Krasnoyarsk krai, and the Republic of Sakha (Yakutia)) are selected based on an analysis of remote monitoring data. The probability of a BC cloud from model fires transferring to the snowy-ice surface of the Arctic is analyzed using the HYSPLIT trajectory model. The probability of a particle emitted from the boreal taiga zone to traverse the sea ice-covered part of the Arctic Ocean is found to be between 1–10%. Effects of BC (the balance of shortwave radiation) on the Arctic climate are estimated on the basis of global climate model of the Institute of Numerical Mathematics Russian Academy of Sciences (INM RAS). According to the results of model experiments, the effect of BC on the balance of shortwave radiation from all model fires in the Northern Hemisphere is 0.11 W m–2 under cloudy conditions and 0.21 W m–2 in a clear sky. The estimated effect on the shortwave radiation balance is a 1.5–2% larger income when compared to the scenario without emission sources. The simulation results showed that the effect of BC emissions from forest fires on the ice-covered Arctic region is negligible. [ABSTRACT FROM AUTHOR]

Black carbon (BC) aerosol particles in the Arctic heat the atmosphere and snow/ice surfaces and may strengthen the snow-albedo feedback that amplifies Arctic warming. Model simulations of BC concentrations in the Arctic depend strongly on the representation of microphysical processes such as aging, activation, and wet removal. Most BC modeling studies have classified BC particles into hydrophobic BC, which cannot form cloud droplets, and hydrophilic BC, which can form cloud droplets, by assuming a globally constant critical supersaturation threshold value (Sthre), without considering its consistency with cloud maximum supersaturation (Smax). Here we show that it is essential to consider the consistency of Sthre with Smax in global model simulations to reduce uncertainties in near-surface ambientBCconcentrations in the Arctic. Previous studies often obtained good agreement between simulated and observed near-surface Arctic BC mass concentrations when a low Sthre (;0.1%) was assumed in their models. However, this Sthre may be too low (activation and wet removal of BCmay be underestimated) for the Arctic, because some recent observations and our model simulations suggest that Smax may actually be higher (;0.3%) there. We also demonstrate that spatially varying Sthre values and their consistency with Smax, which previous studies did not consider, must be represented in models for more accurate estimation of BC budget in the Arctic. Because both Smax and BC-aging speed depend on climatic conditions, our findings are an important step toward better simulations of BC impacts on past, present, and future Arctic climates. [ABSTRACT FROM AUTHOR]

There is ample evidence that Black Carbon (BC) is harmful to the Arctic. BC can darken the otherwise highly reflective surfaces of snow and ice and increase atmospheric and ice surface temperatures. Because of the importance of BC to the Arctic, this work was designed to resolve the most significant source regions of Arctic BC as measured by monitoring stations in the Arctic. Using a bottom‐up approach, it is shown for the first time that there is one particular BC transport pathway from lower latitudes into the Arctic that registers at all but one of the Arctic surface monitoring stations included in this study. Through this pathway, pollutants are transported from the Indo‐Gangetic plane over Central Asia into the high Arctic in as little as 7 days. The measurement sites and BC pathways in this study are shown to be well representative of the Arctic as a whole. Plain Language Summary: Snow and sea ice are two of the most reflective surfaces occurring naturally on planet Earth. Light absorbing aerosols, such as wind blown black carbon, that stick to these pristine surfaces can make them less reflective, thus converting more sunlight into heat. The added heat leads to increased surface temperatures and is detrimental to the Arctic climate. There are few sources of light absorbing aerosols in the Arctic compared to the vast amounts of black carbon aerosols that are emitted closer to the equator. This research highlights an important pathway for light absorbing aerosols to enter the Arctic. Light absorbing aerosols that enter the Arctic through this pathway can then subsequently spread out throughout the Arctic. This pathway is shown to transport light absorbing airborne pollutants from South Asia, over Central Asia, and into the high Arctic in quantities that well exceed the background levels, thus highlighting the importance of this newly found pathway. Key Points: Black Carbon aerosols can travel from South Asia over Central Asia and to the Arctic in 7 daysBlack Carbon transported via this pathway measures well above the station average at almost all Arctic stationsThe identified pathway is significant for Black Carbon concentrations throughout the Arctic [ABSTRACT FROM AUTHOR]