Progress is being made in efforts to minimize the impacts of climate change. After the Paris Agreement, adopted in 2015, set the goals of keeping the long-term temperature increase well below 2℃ and of pursuing efforts to limit the temperature rise to within 1.5℃ from the pre-industrial period, the Intergovernmental Panel on Climate Change (IPCC) issued a special report on the 1.5℃ goal in 2018. Since then, the world has come to share the recognition that we should first aim for a limit of 1.5℃ instead of 2℃. To that end, the total amount of global carbon dioxide (CO2) emissions must be reduced to net zero by 2050, The term “net zero,” in this context, expresses a situation where any emissions are balanced by schemes to offset an equivalent amount of greenhouse gases from the atmosphere, such as by planting trees or using technologies like carbon capture and storage. Carbon neutral and decarbonization are also similar terms. Based on this newly set goal, many countries have set net zero emissions as a long-term goal. In this special issue, members of the Asia-Pacific Integrated Model (AIM), an international project that has been ongoing for more than 20 years, will introduce the latest net zero research results in major Asian countries. Asia as a region has had some of the largest increases in greenhouse gas emissions in the world, and achieving net zero emissions in this region will be essential for achieving the analogous global target.

A decarbonized global society will require expanded deployment of renewable energy in Asia more than in any other region due to its large population and fast development compared to other world regions. Thus, the possibility of a decarbonized society in Asia depends first on the availability of renewable energy resources, which, in turn, depends on geographic and climatic conditions along with the status of technologies. This paper presents estimates of two major renewable resources, solar and wind, in terms of energy potentials from a model using georeferenced data. The outcomes are compared with current energy demand in Asian countries, and are discussed with respect to some of the gaps to be filled to secure the expansion of the region’s renewable energy supply.

Japan enacted legislation in 2021 incorporating the aim of achieving net zero greenhouse gas (GHG) emissions by 2050 based on temperature targets set in the Paris Agreement. Our research attempted to quantitatively express the combination of technologies, energy supply and demand, and structure of GHG emissions required to achieve net zero GHG emissions by 2050. The combination of measures necessary to achieve this goal was estimated by using a computable general equilibrium model, a technology selection model and an optimal generation planning model while considering factors including the consistency of the future economy and energy demand, feasible technology deployment speed and the maintenance of regional and temporal balances for electricity demand and supply. The results show that major changes in the energy system will be necessary, including shifting from fossil fuel to electricity, expanding the use of hydrogen and hydrogen-based fuels, and expanding the use of renewable energy. Also, negative emission measures will be required to address residual emissions. In addition, reducing energy demand through social transformation was shown to reduce dependence on measures the efficacy of which is highly uncertain and thereby increase the possibility of achieving net zero GHG emissions. These findings are also applicable to building a decarbonized society in Asian countries, while taking into account each country’s stage of development and taking advantage of climatic and regional characteristics.

Much research suggests that energy transitions have been driven mainly by CO₂ emission reduction targets. There are, however, other issues that could be included in assessing an energy transition in China. It would be possible to apply multiple objectives in assessing a transition. This paper presents ways to analyze energy transitions using multiple objectives with the Integrated Policy Assessment model for China (IPAC model). The use of multiple objectives of energy transition may be better for exploring factors influencing a transition, and provide a wider understanding of the energy transition by involving more stakeholders in the transition pathways. An energy transition towards a carbon-neutrality target would have the characteristics of clean energy, such as renewable and nuclear energy, dominating the energy mix, resulting in improved air quality and water demand control. Even though the use of carbon capture and storage (CCS) for fossil fuels may negatively impact energy for air pollutant control due to increased fossil fuel energy use, the amount of fossil fuel that can be used with CCS in energy transition pathways is also limited. Moreover, proper investments in energy transition could also benefit China’s economic development. On the whole, adopting an energy transition pathway with a carbon-neutrality target in China could also support the realization of China’s Sustainable Development Goals (SDGs) by 2030.

In 2021, Indonesia announced that it would expand its climate change mitigation commitment with an eye to achieving net-zero emissions by 2060 while at the same time continuing to strive to achieve its medium-term emission reduction target, which is stated in its Nationally Determined Contributions (NDC). However, over the last few decades, there has been no significant reduction in emissions, and this has become a signal for Indonesia to accelerate its emission reduction actions. This study aims to summarize the dynamics of emission mitigation policies in Indonesia and the various constraints accompanying them. Some of the most frequent key challenges are technical constraints at the sectoral level, limited funding, knowledge gaps at the local level, land acquisition and public acceptance. However, apart from the complexity of these problems, Indonesia has also gradually made some progress, such as improving and maintaining communication among stakeholders, formulating mitigation policies that involve more local community participation, and seeking alternative financing to support the country’s emission mitigation projects.

The trend of rising greenhouse gas (GHG) emissions in Thailand is a matter of concern, demanding ambitious mitigation efforts beyond 2030 and even before then to contribute towards meeting the long-term goal of the Paris Agreement of staying within a 1.5°C temperature rise. Carbon dioxide (CO₂) emissions form the major part of the total GHG emissions in Thailand. This study aims to explore the energy, environmental and macroeconomic impacts of limiting CO₂ emissions during 2010–2050 for the underlying target of achieving carbon neutrality by 2050. This study has developed a recursive dynamic Asia-Pacific Integrated Model/Computable General Equilibrium (AIM/CGE) model for Thailand which is soft-linked with the AIM/Enduse model. In addition to a business-as-usual (BAU) scenario, the study has formulated two different CO₂-mitigation scenarios, each indicating a carbon-neutrality pathway towards 2050. Results indicate that Thailand should put more effort into mitigation actions to achieve carbon neutrality by 2050. Expansion of renewable-energy-based technologies, improvement of end-use energy efficiency, fuel-switching and deployment of carbon capture and storage (CCS) technologies in both the power and industrial sectors are identified as important mitigation measures for Thailand in curbing CO₂ emissions by 2050. The results show that the introduction of such mitigation measures would provide CO₂ emission reductions, but at the expense of economic losses. The price of CO₂ mitigation was found to vary from 220 to 332 US dollars per ton of CO₂ (tCO₂) in 2050 under the two carbon-neutrality scenarios.

Vietnam’s Prime Minister has committed the country to developing and implementing strong greenhouse gas (GHG) emission reduction measures with its own resources, with the cooperation and support of the international community, to achieve net-zero emissions by 2050. This paper introduces three models, Extended Snapshot, AIM/Enduse and AIM/CGE, that were used to assess the emissions, technology options and economic impacts of reducing the GHG emissions in the Net Zero Emissions scenario. The results show that 1) GHG emissions will reach their peak at 511 MtCO₂ in 2030, and decrease to zero by 2050; 2) renewable energy and carbon capture and storage (CCS) are fundamental technologies for achieving great GHG emission reductions; and 3) the amount invested will be about 300 to 400 billion USD in the “Net Zero-CCS” (NZ-CCS) and “Net Zero-Renewable” (NZ-REN) scenarios, respectively. These findings imply that the goal of net-zero emissions is realizable in our simulations, but technological progress and diffusion as well as effective implementation of country-relevant climate policies will be indispensable.

Nepal aims to achieve carbon neutrality by mid-century. This study aims to analyze the energy sector transformation needed to achieve the carbon neutrality target. The study employs the AIM/Enduse model as a modelling tool to analyze the energy system. A business-as-usual (BAU) scenario is developed in which energy and technological use follow historical trends. The carbon dioxide (CO₂) emissions in the energy sector in BAU would reach 66.3 MtCO₂ in 2050. The study also assesses the carbon budget and carbon dioxide emission allowance with various effort-sharing approaches. Based on the estimated emission allowances, the emission pathway in the energy sector is determined to develop an emission reduction (ER) scenario. The ER scenario also incorporates the Nationally Determined Contributions (NDC) targets of Nepal. In the ER scenario, CO₂ emissions from the energy sector in Nepal peak in 2036, then drop, reaching 6.4 MtCO₂ in 2050. The ER scenario would require energy efficiency improvement and electrification of the end-use technologies in all the sectors; and fuel-switching from coal and oil to biomass in addition to electrification in thermal applications in industries. The electricity consumption in the ER scenario would be higher by 70% compared to the BAU scenario in 2050. Hydro, solar and biomass would have crucial roles in the decarbonization of the energy sector. In the ER scenario, the combined power generation capacity of hydropower, solar and wind would reach 72 GW by 2050, which in the BAU scenario would be 37 GW. Policies and incentives that would promote the electrification of end-use technologies and renewable power generation need to be formulated to achieve the mitigations of the ER scenario.

This study used the AIM/CGE [Laos] model to assess contribution of sustainable municipal solid waste management (MSW) to decarbonization in Laos by introducing a “waste-to-sources” approach including policies such as increasing the waste collection rate and solid waste recycling, which uses waste as energy. In Laos, common practices for handling solid wastes are direct dumping and open burning, and a government report (MONRE, 2022) on the state of pollution in Laos has noted that along with from road transport emissions, which are a main source of urban air pollution, improper waste disposal also threatens urban air quality in the main cities of Laos. Our model sets two scenarios: a business as usual (BaU) scenario in which waste dumping practices before treatment by households remain unchanged in the future, and a countermeasures (CM) scenario in which direct waste dumping decreases significantly under the assumption of the waste collection rate reaching 100% by 2050. Greenhouse gas (GHG) emissions from MSW management under the BaU scenario increase by a factor of nearly seven by 2050. However, by introducing MSW recycling, GHG emissions can be reduced to 93% in 2050 compared to those of the BaU scenario. An increase in recycling rates will provide more recycled materials to the production sector, which will result in decreased GHG emissions in the sectors to which the recycled materials are provided. In the recycling sector, however, the result will be an increase in energy-related carbon dioxide (CO₂) emissions. To achieve decarbonization in Laos, performing material recycling through energy-efficient processes will be important.

Carbon pricing is one of the main policies for improving energy efficiency and achieving carbon reduction. This study has aimed to investigate how to use carbon pricing revenues well to mitigate negative effects on the economy. Relying only on carbon pricing policies can result in high economic costs; in particular, the energy-intensive industrial sectors suffer greater impacts. We propose that providing subsidies to sectors based on their respective carbon pricing payments could mitigate the negative effects on the GDP better than the other examined scenarios of providing the carbon pricing revenues to the fiscal budget or providing subsidies to sectors based on their respective contributions to emission reductions. Thus, proper design of the use of carbon pricing revenues could mitigate the negative economic effects of carbon pricing.