South Asia is characterized by a large diversity of landscapes, ranging from high mountain areas to tropical islands. Consequently, the region experiences almost every possible consequence of climate change, from glacial outburst floods to heatwaves, droughts and fires. This variety in impacts, combined with a large diversity of social, economic and cultural contexts, also means that the responses to a changing environment are often locally specific. In this Viewpoint, local researchers discuss what they see as the most pressing science questions on mitigating and adapting to climate change in their scientific fields and in their regions. They highlight that South Asia has seen substantial progress in understanding the impacts and developing responses to global warming and argue that more communication between scientists and decision-makers and collaboration between actors and across borders are key to respond to these challenges.

Energy efficiency is promoted worldwide as an important measure to address growing energy demand and reduce energy intensity of the gross domestic product and emissions of greenhouse gases and air pollutants. We analyzed aggregate and sectoral energy intensities in Bangladesh, India, Nepal, Pakistan, and Sri Lanka during 2000–2017 and decomposed the aggregate energy intensity into its four key determinants. Past energy intensity analysis methods have often used changes in factors related to only energy and economic structure and ignored energy equity factors. We show that energy equity factors (access to electricity and per capita electricity consumption) strongly influence the energy intensity of a country/region. In countries with less than 100% access to electricity, changes in energy equity factors negatively affected energy intensity while changes in energy structure and income level improved it. Energy equity is an important consideration for assessment, development and implementation of sustainable energy efficiency policies of a country.

The grid power supply in many developing countries is insufficient and irregular resulting in many commercial users relying on inefficient and air pollution intensive off-grid captive diesel generators (DGs) as a backup power supply. This study investigates the fuel consumption and emission level of such DGs and explores the possibility of reducing them through the formation of a microgrid of DGs and solar PV in a commercial area in Kathmandu, Nepal. An optimized microgrid system has been designed using the HOMER framework for both DGs and solar PV based systems. The optimized DG based microgrid results reduction in specific fuel consumption by 19% and cost by 5%. It also mitigates emissions of key air pollutants (PM2.5, PM10, CO, and VOCs) by 21% to 92% as compared to the baseline. If the solar PV based microgrid is used, the emissions can be reduced by 100% but cost increases by 27%. However, the overall economic benefit to the country could be quite significant due to the reduction of external costs of imported fossil fuel and generators, air pollution, adverse health outcomes, investment locking in grey power generation, and energy security issues. The approach used here can be emulated in many other developing countries with similar conditions.

There is a growing number of national, subnational and even company targets for net-zero emissions of CO2 in support of the Paris Climate Agreement goals of limiting the global average temperature increase within 1.5 ◦C by 2100. The challenges faced by developing countries in achieving net-zero emissions targets are, however, very prominent due to their common desire for rapid economic growth, improved socio-economic conditions, and greater climate resilience. In addition, this has to overcome many constraints related to the competitiveness, acceptability, and sustainability of proposed and planned low-carbon initiatives. It is thus very important to understand the economic and technical characteristics of net-zero emissions concepts and pathways. The constraints can best be addressed if actual and transparent co-benefits related to these initiatives are identified and reflected during their implementation. Here we employ the Low Emissions Analysis Platform (LEAP) to examine Nepal’s recently introduced ‘Long-term Strategy for Net-zero Emissions’ and to estimate anticipated co-benefits in terms of reducing air pollutants emission and enhancing energy security and energy equity. Under the reference scenario (REF), the annual CO2 emission is expected to increase from 23 MtCO2 in 2019 to 79 MtCO2 in 2050 with significant increase in air pollutants emissions in the range of 60% (Organic Carbon) to 183% (SO2), increase in energy import dependency, reaching electricity consumption per capita below one-quarter of the world average. Under the ‘With Additional Measures (WAM)’ strategy scenario, air pollutants would be reduced in the range of 70% (Organic Carbon) to 85% (Black Carbon) respectively, in 2050 as compared to the REF. Similarly, it results drastic improvement in energy security indicators and energy equity. It is expected that the findings of this study will provide useful input to policymakers, private sector, societal actors and researchers in support of successful implementation of the initiatives for sustainable socio-economic transformation pathways.