Mitigating the impacts of air pollutants in Nepal and climate co-benefits: a scenario-based approach

Short-lived climate pollutants (SLCPs) including black carbon (BC), methane (CH4), and tropospheric ozone (O3) are major climate forcers after carbon dioxide (CO2). These SLCPs also have detrimental impacts on human health and agriculture. Studies show that the Hindu Kush Himalayan (HKH) region, which includes Nepal, has been experiencing the impacts of these pollutants in addition to greenhouse gases. In this study, we derive a national-level emission inventory for SLCPs, CO2, and air pollutants for Nepal and project their impacts under reference (REF) and mitigation policy (POL) scenarios. The impacts on human health, agriculture, and climate were then estimated by applying the following: (1) adjoint coefficients from the Goddard Earth Observing System (GEOS)-chemical transport model that quantify the sensitivity of fine particulate matter (PM2.5) and surface O3 concentrations in Nepal, and radiative forcing in four latitudinal bands, to emissions in 2 × 2.5° grids, and (2) concentration–response functions to estimate health and crop loss impacts in Nepal. With the mitigating measures undertaken, emission reductions of about 78% each of BC and CH4 and 87% of PM2.5 could be achieved in 2050 compared with the REF scenario. This would lead to an estimated avoidance of 29,000 lives lost and 1.7 million tonnes of crop loss while bringing an economic benefit in present value of 2.7 times more than the total cost incurred in its implementation during the whole period 2010–2050. The results provide useful policy insights and pathways for evidence-based decision-making in the design and effective implementation of SLCP mitigation measures in Nepal

Integration of climate change mitigation and sustainable development planning: Lessons from a national planning process in Nigeria

To limit global temperature increases to ‘well below 2 ºC’, it is necessary that current national commitments to reduce emissions are increased, and these commitments are implemented. The identification of local development benefits from climate change mitigation is a possible motivating factor to achieve this. However, there is a lack of practical examples of how climate change mitigation and development priorities can be integrated in national planning processes, particularly in low- and middle-income countries. This work considers two questions i) What are the factors that have to be considered when developing a plan integrating GHG reductions with local development goals?; and ii) How do you structure a process to reach a consensus about the plan itself?. It does this by conceptualising the integration of climate mitigation and development benefits as a policy intervention. As a case study, a national planning process that integrated climate change mitigation with improvements to air quality and human health in Nigeria is conceptualised, ex-post, as an intervention theory model. The key factors identified include the importance of tailoring the planning process to the national context of how development priorities are identified and then used in the allocation of national budgets. In particular, assessments undertaken within the planning process, of emission reductions, and development of implementation pathways provided necessary information on how climate mitigation actions contribute to national development priorities. Additionally, the importance of structuring these assessments within a planning processes that also engaged key stakeholders to allow the information produced by the assessments to be informed, and acted upon, by those responsible for mitigation in each key sector is also highlighted. Finally, approaches for the use of intervention theory as a conceptual framework to design a planning process, ex-ante, are discussed, to further optimise the integration of development priorities into climate change planning

Integrated climate change and air pollution mitigation assessment for Togo

Togo, in west Africa, is vulnerable to the impacts of climate change, but has made a negligible contribution to causing it. Togo ratified the Paris Agreement in 2017, committing to submit Nationally Determined Contributions (NDCs) that outline Togo's climate change mitigation commitment. Togo's capital, Lomé, as well as other areas of Togo have ambient air pollutant levels exceeding World Health Organisation guidelines for human health protection, and 91 % of Togolese households cook using solid biomass, elevating household air pollution exposure. In Togo's updated NDC, submitted in 2021, Togo acknowledges the importance and opportunity of achieving international climate change mitigation targets in ways that improve air quality and achieve health benefits for Togo's citizens. The aim of this work is to evaluate priority mitigation measures in an integrated assessment of air pollutant, Short-Lived Climate Pollutant (SLCP) and Greenhouse Gas (GHG) emissions to identify their effectiveness in simultaneously reducing air pollution and Togo's contribution to climate change. The mitigation assessment quantifies emissions for Togo and Grand Lomé from all major source sectors for historical years between 2010 and 2018, for a baseline projection to 2030 and for mitigation scenarios evaluating ten mitigation measures. The assessment estimates that Togo emitted ~21 million tonnes of GHG emissions in 2018, predominantly from the energy and Agriculture, Forestry and Other Land Use sectors. GHG emissions are projected to increase 42 % to 30 million tonnes in 2030 without implementation of mitigation policies and measures. The implementation of the ten identified priority mitigation measures could reduce GHG emissions by ~20 % in 2030 compared to the baseline, while SLCPs and air pollutants were estimated to be reduced more, with a more than 75 % reduction in black carbon emissions in 2030. This work therefore provides a clear pathway by which Togo can reduce its already small contribution to climate change while simultaneously achieving local benefits for air quality and human health in Togo and Grand Lomé

Microenvironmental modelling of personal fine particulate matter exposure in Accra, Ghana

The health burden from exposure to fine particulate matter (PM2.5) is disproportionately concentrated in low- and middle-income countries. To evaluate strategies to reduce PM2.5 exposure, the contribution of different sources, both indoor and outdoor, to overall personal PM2.5 exposure needs to be identified. Despite this, exposure to PM2.5 from indoor and outdoor origin are most often considered separately. This work presents the first application of a microenvironmental modelling approach in a sub-Saharan African city (Accra, Ghana) to estimate personal PM2.5 exposures to population groups disaggregated by gender and age and identify the key factors determining these exposures. Time-activity profiles for each population group were combined with PM2.5 concentrations estimated for three home microenvironments using a dynamic microenvironmental model, INDAIR, and for work, school and transport microenvironments using a steady-state model to estimate personal PM2.5 exposures. In Accra, cooking using charcoal, compared to liquified petroleum gas (LPG), was estimated to result in substantially higher home PM2.5 concentrations, and higher personal PM2.5 exposure for the female adult and child population groups, compared with the male population groups. In households cooking using charcoal, more than 60% of total personal PM2.5 exposure was estimated to be due to residential cooking for the child and female population groups, which reduces to less than 10% when LPG was used for cooking, with the remaining contribution from PM2.5 of outdoor origin. The key parameters to which personal PM2.5 exposure estimates are sensitive are the air exchange rate between indoor and outdoors, the kitchen volume, and charcoal emission rates. This study therefore informs on the additional data collection and measurements that could substantially enhance the parameterisation of micro-environmental models for application in low- and middle-income countries where a limited number of studies have been conducted, and improve their utility in assessing strategies to reduce personal air pollution exposure of different population groups