Abstract
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.
Highlights
Air quality management and climate change mitigation are two inexorably linked environmental challenges of the twenty-first century
Studies have shown that short-lived climate pollutants (SLCPs)—including methane (CH4), black carbon (BC), and tropospheric ozone (O3)—contribute to near-term climate change, as well as adverse impacts on human health and agriculture (IPCC 2014; Ramanathan and Carmichael 2008; UNEP/WMO 2011)
The results indicate that crop losses can be greatly reduced in the POL scenario compared with the REF scenario (Fig. 3)
Summary
Air quality management and climate change mitigation are two inexorably linked environmental challenges of the twenty-first century. Addressing them in a coordinated manner can simultaneously slow down the rate of climate change and protect human health and ecosystems, including agriculture. Studies have shown that short-lived climate pollutants (SLCPs)—including methane (CH4), black carbon (BC), and tropospheric ozone (O3)—contribute to near-term climate change, as well as adverse impacts on human health and agriculture (IPCC 2014; Ramanathan and Carmichael 2008; UNEP/WMO 2011). An integrated approach to addressing air quality and climate change as part of the policy process will offer a great opportunity to contribute to meeting sustainable development goals (SDGs), they are not explicitly stated as such (Haines et al 2017)
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