Responses of Arctic black carbon and surface temperature to multi-region emission reductions: a Hemispheric Transport of Air Pollution Phase 2 (HTAP2) ensemble modeling study

Na Zhao,Simone Tilmes,Tom Kucsera,Daven Henze,Marianne Tronstad Lund,Kan Huang,Joshua S Fu,Mian Chin,Xinyi Dong,Yun Fat Lam,Kengo Sudo

doi:10.5194/acp-21-8637-2021

Abstract

Abstract. Black carbon (BC) emissions play an important role in regional climate change in the Arctic. It is necessary to pay attention to the impact of long-range transport from regions outside the Arctic as BC emissions from local sources in the Arctic were relatively small. The task force Hemispheric Transport of Air Pollution Phase 2 (HTAP2) set up a series of simulation scenarios to investigate the response of BC in a given region to different source regions. This study investigated the responses of Arctic BC concentrations and surface temperature to 20 % anthropogenic emission reductions from six regions in 2010 within the framework of HTAP2 based on ensemble modeling results. Emission reductions from East Asia (EAS) had the most (monthly contributions: 0.2–1.5 ng m−3) significant impact on the Arctic near-surface BC concentrations, while the monthly contributions from Europe (EUR), Middle East (MDE), North America (NAM), Russia–Belarus–Ukraine (RBU), and South Asia (SAS) were 0.2–1.0, 0.001–0.01, 0.1–0.3, 0.1–0.7, and 0.0–0.2 ng m−3, respectively. The responses of the vertical profiles of the Arctic BC to the six regions were found to be different due to multiple transport pathways. Emission reductions from NAM, RBU, EUR, and EAS mainly influenced the BC concentrations in the low troposphere of the Arctic, while most of the BC in the upper troposphere of the Arctic derived from SAS. The response of the Arctic BC to emission reductions in six source regions became less significant with the increase in the latitude. The benefit of BC emission reductions in terms of slowing down surface warming in the Arctic was evaluated by using absolute regional temperature change potential (ARTP). Compared to the response of global temperature to BC emission reductions, the response of Arctic temperature was substantially more sensitive, highlighting the need for curbing global BC emissions.

Highlights

Black carbon (BC) is one of the short-lived climate forcers (SLCFs; AMAP, 2015) and was regarded as the secondlargest contributor to global warming, only inferior to carbon dioxide (Bond et al, 2013)
This study aims to investigate the responses of Arctic BC concentrations and surface temperature to 20 % anthropogenic emission reductions from different regions in the Northern Hemisphere (NH)
CAMchem, CHASER_re1, GEOS-Chem, GOCART, and Oslo CTM3 in the Hemispheric Transport of Air Pollution Phase 2 (HTAP2) experiment were used in this study to estimate the responses of Arctic BC to multi-region emission reductions in 2010

Summary

Introduction

Black carbon (BC) is one of the short-lived climate forcers (SLCFs; AMAP, 2015) and was regarded as the secondlargest contributor to global warming, only inferior to carbon dioxide (Bond et al, 2013). BC is the most efficient atmospheric particulate species at absorbing visible light (Bond et al, 2013); the added atmospheric heating will subsequently increase the downward longwave radiation to the surface and warm the surface (AMAP, 2011). The surface albedo of snow and ice could be reduced and further enhanced the absorption of solar radiation at the surface. In the Arctic, surface temperature responses were strongly linked to surface radiative forcing as the stable atmosphere of the region prevented rapid heat exchange with the upper troposphere (Hansen and Nazarenko, 2004)

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