Pathways to Reduce Black Carbon

Efforts to reduce black carbon (BC) are lagging as emissions rise in low- and middle-income countries. Global action on BC has been hindered by a lack of comprehensive and binding international agreements specifically addressing the issue. Despite its detrimental impact on climate change and human well-being, BC is not included in the United Nations Framework Convention on Climate Change (UNFCCC) list of climate pollutants and is therefore often excluded from national climate plans.  

Fortunately, there is a way forward if science-backed actions are immediately taken. Deployment of proven technologies in high-emitting sectors, targeted interventions at hotspots, strong multinational policies, enhanced environmental regulations, and international cooperation among governments, international organizations, and civil societies can rapidly reduce BC emissions by 2030.  

To reduce global BC, it is imperative that policies and actions, such as those explored below, be implemented to curb emissions.

3.1. Rapidly Adopt Clean Cooking Fuels

Target Residential Hotspots

Forty-two percent of global residential BC emissions emanate from India, Pakistan, Bangladesh, Nigeria, Uganda, Ethiopia, and South Africa due to the use of unclean cooking fuel. The Indo-Gangetic Plains is the largest hotspot of residential emissions, followed by densely populated regions in Nigeria and Uganda. Targeted interventions in these regions can drastically reduce global BC emissions, improve the lives of billions of people, and rapidly reduce deforestation across East Africa.

Incentivize Adoption Through Favorable Policies

Several years of research has shown that favorable policies, government subsidies that support affordability, and infrastructure that allows for the reliable replacement of unclean fuel is vital for the adoption of clean cooking fuels.

Out of more than 40 countries where a large portion of the population do not have access to clean cooking, only eight have advanced policies to promote its adoption. Favorable policies can result in rapid uptake of clean cooking fuels. India, for instance, has benefited from the Pradhan Mantri Ujjwala Yojana (PMUY) scheme which has resulted in free liquified petroleum gas (LPG) connections to 96 million households living below the poverty line.

While the initial success of the PMUY scheme is commendable, the initiative has been hindered by below-average refueling rates of the LPG* cylinders by more than 50% of the recipients. This indicates that the long-term penetration of clean cooking fuel is challenging, so related policies should be dynamic and adjusted as needed to increase adoption and utilization.

As electricity availability and capacity increases in low- and middle-income countries, electric cooking can and must be expanded quickly in urban areas. According to the International Energy Agency (IEA), in the most cost-effective and realistic scenario to provide universal access to clean cooking by 2030, electric cooking plays a major role by becoming the main choice for 12% of households. It is imperative that governments promptly implement policies that facilitate the seamless adoption of electric cooking.

Policymakers in nations with low penetration must make clean cooking a national priority. There are a range of mechanisms that they can employ, including targeted subsidies to improve affordability, using diverse and culturally acceptable clean cooking fuels and stoves, integrating clean cooking across cross-sectoral planning, tapping into the rapidly growing carbon market, educating people on the benefits of clean cooking fuels, and eliminating taxes and levies on clean cooking fuels and appliances.

Prioritize Climate Finance Investments in Clean Cooking

Clean cooking solutions offer a unique opportunity to simultaneously address climate change, health, and development challenges. Yet clean cooking initiatives in sub-Saharan Africa are vastly underfunded and investments remain several magnitudes lower than the US$8–10 billion required annually for a universal transition by 2030. For a long time, clean cooking solutions have suffered from a lack of investments by private finance. International developmental banks must reevaluate their approach to clean cooking investment and adopt innovative strategies such as concessional and blended finance to attract more private capital to achieve universal access. Innovative funding mechanisms like the Spark+ Africa investment fund and Energy Sector Management Assistance Program (ESMAP) provide viable pathways to deliver the necessary financing for a clean cooking transition.

* Even though LPG is a fossil fuel, it is the best option to reduce BC and carbon dioxide emissions from the residential sector in low- and middle-income countries due to its affordability, reliability, and availability. The IEA recognizes LPG as a clean cooking fuel option as these countries transition away from unclean alternatives. 

3.2. Promote Cleaner Transportation to Reduce and Prevent Emissions

In the last decade, transportation-related BC emissions have declined in the United States, European Union, and China due to stricter air quality regulations and improvements in diesel engines. For example, in the United States, vehicular emissions of BC have decreased by 60% in the past 30 years due to regulations focused on particulate emissions from diesel vehicles. In these countries, BC is expected to decline even further due to the rapid deployment of hybrid and electric vehicles (EVs). 

In contrast, BC emissions from the transportation sector have been increasing in South Asia due to rising populations and growing demand for vehicles, a trend that will likely continue unless significant action is taken to reduce emissions. 

Though transportation-related emissions in sub-Saharan Africa are currently several times lower than residential sources, this could rapidly change in response to growing transportation demand. Indeed, under current policy, Africa could account for more than one-third of global transportation BC emissions by 2040. Such an increase could offset the gains - if any - made by reducing residential emissions.

Rapidly Expand Cleaner Diesel Vehicles and Low-Sulfur Fuel

BC emissions from diesel vehicles can be significantly reduced by using diesel particulate filters (DPF). Vehicles following recent standards (Euro 6 and Euro 4 standards for heavy and light duty vehicles, respectively) are capable of removing more than 90% of BC emissions from exhaust. Global adoption of high-efficiency DPF can result in a significant reduction in transportation BC by 2040. Yet, the majority of the countries have not adopted the latest standards for new diesel vehicles. 

Countries need to urgently adopt policies that phase out older vehicles, establish updated regional standards, and raise awareness of the harms of BC vehicle emissions. Adopting cleaner vehicles can be costly, however, they result in significant societal benefits. According to the International Council on Clean Transportation (ICCT) rapid adoption of Euro 6 and Euro 4 vehicle standards can avoid up to $7 trillion in societal costs from 2020 to 2050.

Target Clean Transportation in Urban Metropolises

Globally, transportation-related BC emissions are highest in urban areas. Rapidly adopting EVs and hybrid vehicles in urban areas of low- and middle-income countries can reduce current BC emissions and prevent future increases as vehicle demand grows. Expanding such vehicles in urban areas is also easier due to a higher degree of electrification and a greater ability to develop the required infrastructure.

Currently, the proportion of EVs in low- and middle-income countries is minimal. Policies that subsidize hybrids and EVs and increase investments in essential infrastructure for public charging are urgently needed. Strategic approaches that prioritize the electrification of high-efficiency, high-occupancy modes of transportation, like bus rapid transit (BRT) systems, as well as electric-powered two-wheeled scooters and three-wheeled rickshaws which are significantly cheaper and widely used in low- and middle-income countries can reduce costs while maximizing benefits. Kenya, for instance, has expressed its intention to incorporate electric buses into the Nairobi Bus Rapid Transit system, while Rwanda has implemented tax exemptions for EV sales.

Improved air quality from reduced tailpipe emissions will have significant health co-benefits, especially in densely populated areas, which can help offset the cost associated with implementing these solutions. For example, a nationwide transition to 100% zero-emission passenger vehicles in the United States by 2035 and medium- to heavy-duty trucks by 2040, could result in US$1.2 trillion in public health benefits from 2020 to 2050 including preventing 110,000 premature deaths due to improved air quality. The benefits of this transition will be much bigger in low- and middle-income countries.

Leverage Innovative Financing

To ensure widespread transitions to EVs, national investments alone will not suffice. International finance, private capital, collaboration, and knowledge sharing is imperative. Funding for clean electricity projects in low- and middle-income countries is urgently required to support local EV startups and promote technological advancement. Unfortunately, investments in such projects in Africa are constrained due to substantial risks associated with high upfront costs, currency fluctuations, and inadequate patient capital.

To address these challenges and enable large-scale investment, innovative financing structures must be implemented. One such approach could involve concessional finance through multilateral development banks to expedite crucial projects, thereby encouraging subsequent private investment. Alternatively, risk-sharing arrangements can be established to alleviate concerns among risk-averse investors.

Reduce BC from the Shipping Industry

With new shipping routes opening in the Arctic Sea due to melting sea ice, it’s imperative that BC emissions from the shipping industry be urgently reduced to prevent a positive feedback loop in which even more sea ice melts as passing ships deposit heat-absorbing BC. According to the Clean Arctic Alliance, shifting Arctic shipping from heavy fuel oil to cleaner distillate fuel can result in a 44% reduction in BC emissions. Additionally, by equipping all ships with DPF BC emissions could be further reduced by as much as 90%.

Emissions from the shipping industry can be easily reduced by existing technologies through policies such as expanding or establishing emission control areas, prohibiting the use of heavy fuel, and establishing a BC emissions standard for ships.

3.3. Enact Air Quality Policies and Establish a Monitoring System

Enact Stringent Emissions Standards

BC emissions from the industrial and agricultural sectors cannot be reduced without enacting strong emissions standards, legislating clean air laws, setting robust baselines, and establishing mandatory monitoring programs.

For industrial emissions, stronger regulations can include replacing beehive coke ovens with improved ovens, modernizing traditional brick kilns, mandatory installation of emission control technologies, and regular monitoring and reporting requirements to ensure compliance. The benefits of strong emissions standards are visible in the European Union, North America, and, to a lesser extent, in China where the installation of dust removal facilities, robust monitoring systems, and transition to mechanical coke ovens have significantly reduced industrial BC emissions.

BC emissions from agricultural burning can be reduced by explicitly prohibiting the practice. Employing a "deterrent and incentive" model, where penalties and fines are imposed on farmers who violate the regulations while those who adopt alternative practices such as composting, mulching, or bioenergy production are financially rewarded, can accelerate cleaner disposal of agricultural waste. This combined approach can lead to a significant reduction in agriculture-related BC emissions.

Legislate Clean Air Quality Laws

Various measures aimed at enhancing air quality can simultaneously reduce BC emissions. As per the Intergovernmental Panel on Climate Change (IPCC), air quality and climate change are intrinsically interconnected. Simultaneously addressing both holds the potential for substantial synergistic effects and economic advantages, while also circumventing policy measures that ameliorate either issue at the expense of exacerbating the other. For example, in China, measures to improve air quality in regions with high pollution significantly reduced BC emissions and contributed to improving public health.

According to a 2021 UN Environment Program (UNEP) report, 34% of countries – mostly in sub-Saharan Africa – have no legal protection for ambient air quality, lacking legislatively-mandated standards. Among these countries, 86% have no air quality standards in place, while the remaining 14% have air quality standards that are limited in scope. Legislating air quality standards in these countries can curb current and future BC emissions.

Target Industrial Hotspots in China

China accounts for about one-third of global industry-related BC emissions (PKU-FUEL). Industrial hotspots are concentrated in China’s highly populated and industrialized eastern states.  Although China, which produces more than half of the world's coke, has made significant strides in reducing BC emissions by installing dust removal facilities and upgrading mechanical coke ovens, the PKU-FUEL data suggests that industrial emissions have not been declining as quickly as those from the residential and transportation sectors. A rapid reduction in industrial BC emissions from China is vital to achieve a global reduction of 30% by 2030. 

Reduce Oil and Gas Related Emissions

Oil-producing Gulf countries like Qatar, the United Arab Emirates, and Iraq exhibit high industrial BC emissions primarily from the oil and gas sector resulting in markedly high per capita emissions. Worse still, these BC emissions are often co-emitted with methane. Fortunately, this means that targeted interventions will significantly reduce both BC and methane emissions from the region.

3.4. Opportunities for Integrating Black Carbon in National Climate Plans and Funding Initiatives

Surprisingly, only twelve countries – Costa Rica, Chile, Canada, Mexico, Zimbabwe, Micronesia, the United States, Ghana, Uganda, Bangladesh, Nigeria, and Eswatini – have explicitly addressed BC in their nationally determined contributions (NDCs). Notably, Mexico, Colombia, Chile, and Bangladesh have committed to reduce emissions by more than 25% by 2030. The lack of momentum to reduce BC emissions can be attributed, in part, to its exclusion from the list of climate pollutants covered by the UNFCCC, an oversight that the organizations should reconsider given the extensive health and climate benefits of reducing BC.

Notwithstanding this exclusion, countries should still consider including BC reductions in their climate strategies. As countries conduct comprehensive reviews of their NDCs and seek to enhance their mitigation efforts by 2025, they have a unique opportunity to introduce or improve targets, policies, and actions specifically aimed at addressing BC emissions. By doing so, each country stands to reduce their impact on the climate while improving human well-being.

Climate funding agencies can play a crucial role to accelerate reductions in BC emissions. First, they should incorporate short-lived climate pollutants, including BC, into their decision-making processes when evaluating grant proposals. This entails a comprehensive assessment of the total emissions reduction potential of each project and prioritizing projects that target SLCPs alongside carbon dioxide. Second, they should also prioritize projects that result in large improvements in human health and well-being. This approach would yield immediate and sustained benefits for the climate while also delivering unparalleled co-benefits to low- and middle-income countries.

Funding institutions like the World Bank and Global Environmental Facility (GEF) have taken initial steps to prioritize projects that address carbon dioxide and BC, however these initiatives need to be rapidly scaled through close collaboration with governments, private funders, impact investors, and philanthropic organizations.

3.5. Improvement in Black Carbon Measurements and Estimates

BC estimates suffer from large uncertainty that arises due to various factors including an incomplete understanding of emission sources, complex atmospheric processes, limitations in measurement techniques, and a lack of consensus on what constitutes BC and how to measure it. Addressing these underlying issues is critical to develop a comprehensive and accurate inventory of BC emissions as well as to design effective emission reduction plans. As with efforts to improve global methane estimates, there is an urgent need for stakeholders to come together to develop a framework that establishes a consistent measurement protocol and identifies opportunities and pathways for improving BC estimates while reducing uncertainties, such as by collecting higher-quality data and better integrating satellite and ground-based observations.