Current Policies, Emission Trends and Mitigation Options for Black Carbon in the Arctic Region. Draft Working Paper for the Task Force on Short-Lived Climate Forcers.

Abstract

The 2007 IPCC Fourth Assessment Report noted that black carbon (BC) may exert a significant anthropogenic warming effect on the global climate. Since then an increasing number of modeling and sampling studies have strongly supported this warming effect. This is especially true in the Arctic and other snow-covered regions, where BC in the atmosphere absorbs more heat over these reflective surfaces; and once deposited, darkens snow and ice to lead to greater melting as well. The melting leads to greater exposure of the darker land and sea below, which in turn absorb more heat, and thus to additional warming and melting. Current studies strongly point to diesel exhaust particulates and open burning (both agricultural burning and wildfires) as the major sources of BC that reach the Arctic from the eight Arctic Council nations. These sources also comprise the greatest part of BC emissions in near-Arctic regions (north of approximately forty degrees latitude), including much of the European Union, Ukraine and China north of Beijing. With increased shipping expected in and near the Arctic due to sea ice loss, several studies also point to marine sources of BC as a major and growing future contributor to emissions. Oil and gas flaring and industrial sources may also contribute to BC emissions with Arctic impact; however the scale of emissions has not been studied sufficiently to determine if these constitute significant sources. There is sufficient evidence to support the reduction of BC emissions from the identified sources (diesel, burning and marine) as a means to slow the rate of warming in the Arctic over the next few decades. Additional study is urgently needed to determine the impact of the potential sources (oil and gas flaring and industrial) and their most cost-effective mitigation measures. This paper begins to identify the most economically and technically feasible options that Arctic nations should begin to consider now in order to reduce near-term temperature rise through BC mitigation measures focused on these three sources. Significant health or other co-benefits are additional reasons to motivate early action. These recommendations primarily include diesel engine measures (e.g., retrofits with particulate diesel filters) and biomass burning measures (e.g., management of springtime burning). Additionally, significant mortality and morbidity could be averted due to air quality benefits from particulate emission reductions.