The Intergovernmental Panel on Climate Change (IPCC) released the report of Working Group III of the Sixth Assessment Report “climate change 2022: mitigating climate change”. The report accessed and summarized the latest research progress on climate change mitigation since the release of the Fifth Assessment Report, which will provide an important reference for the international community to further understand climate change mitigation actions, system transformation, and the pursuit of sustainable development. The report pointed out that human activities had cumulatively emitted about 2.4 trillion tons of CO2 from 1850 to 2019, of which 58% was emitted before 1990. In order to control the level of global temperature rise in the future, deep and immediate mitigation actions are required. In both low and minimum emission scenarios, fossil energy needs to be greatly reduced; renewable energy will be the mainstay of future energy supply; achieving carbon neutrality requires relying on negative emission technologies and increasing carbon sinks. Technological progress is one of the key conditions for helping the world combat climate change. Accelerated and equitable climate action is critical to sustainable development. The report’s conclusions once again show that China’s carbon neutrality target is in line with the mitigation path of the Paris Agreement’s temperature rise target of less than 2℃ and striving to achieve 1.5℃. In the future, China should strengthen special research programs on the national concerns and key contents covered in the report. While strengthening scientific interpretation and effective use of the report’s conclusions, it is also necessary to actively participate in the IPCC scientific assessment process, actively contribute Chinese wisdom, and contribute to the international dissemination of Chinese climate governance concepts.
The Working Group III of the IPCC announced the summary for policy makers and the underlying Sixth Assessment Report “climate change 2022: mitigation of climate change”, on 4 April 2022. This report comprehensively reviews state-of-the-art assessment of the scientific, technical, environmental, economic, and social issues of the mitigation of climate change by updated developments in the literature since the year 2010. It provides an important scientific basis for the scientific community to have an in-depth understanding of global GHG (greenhouse gas) emissions, emission reduction paths at different temperature rise levels, and climate change mitigation and adaptation actions in the context of sustainable development. Based on main conclusions of the report, as well as key scientific issues in terms of regional differences in GHG emissions, mitigation path classification, land use-related emissions assessment and carbon dioxide removal technology assessment, it’s proposed that China should firmly adhere to the “dual carbon” strategic goal in its climate change policies and actions, implement mitigation paths together with the vision of sustainable development, equity and poverty eradication, and accelerate research and development of core science and technology of climate change integrated assessment for enhancement of international influence and voice.
Demand-side mitigation is a critical pathway to achieving carbon neutrality, wellbeing for all, and social equity coordinatively, since it puts “people” at the center of decision and links various Sustainable Development Goals (SDGs) together. The Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) presents an independent chapter (Chapter 5) to address the demand, services, and social aspects of mitigation for the first time. The report links demand-side mitigation with multiple social sustainable development goals and clarifies that the demand-side mitigation targets include not only climate change tackling but also wellbeing and equity improvement. It collects hundreds of demand-side mitigation measures by the “Avoid-Shift-Increase (ASI)” framework and presents the associated mitigation potential. Furthermore, key driving factors of demand-side mitigation, including social culture, psychological activities, technology, and infrastructure, are investigated, as well as the interlinkages among the driving factors. Last but not least, multiple behavioral interventions and policy designs are presented o enhance the motivation and the capacity of demand-side mitigation. This article briefly interprets the main conclusions of IPCC AR6 Chapter 5 and discusses its research and policy implications for China.
The IPCC officially released its Working Group III report, “climate change 2022: mitigation of climate change”, in April 2022. This report builds on the published Working Group I, and Working Group II reports, to assess progress in global climate change mitigation work. Chapter 9 of Working Group III report, provides a systematic and comprehensive assessment of the current trends and drivers of global building sector, technical and non-technical measures to reduce emissions, and quantitative overviews of the potential and costs of global and regional mitigation measures. This report discusses the relationship between mitigation and adaptation measures, sustainable development, and key policy barriers and feasible measures. Global building emissions scenario analysis show that it is possible to achieve net-zero GHG emissions in building sector by 2050 if strong policies for sufficiency, efficiency, and renewable energy are adopted and effectively implemented, and all barriers to decarbonization are removed. If policies are not effectively implemented, there is the potential for decades of high carbon lock-in effect in buildings. There is significant potential for emissions reductions in all regions of the world, in both new and existing buildings. Adopting emission reduction measures in buildings also contributes to achieving the Sustainable Development Goals (SDGs) and using buildings to adapt to future climate change. The main findings of the report will be an important reference for global action on climate change in the building sector, and will be very important implications for China’s building sector to achieve its carbon peak and carbon neutral targets.
The Working Group III contribution to the Sixth Assessment Report of IPCC emphasizes climate change mitigation. The Chapter Transport has provided an overview-based feasibility assessment of the measures to mitigate transport-related greenhouse gases (GHG) emissions. The transport sector had been growing since 1990 and became the fourth largest source in 2019, only after electricity, industry, and the agriculture, forest and land use (AFOLU) sectors. The report focuses on reduction in traffic demand, decarbonization options for land-based transport, shipping and aviation, aiming to reduce transport-related GHG in developed countries and control its growth in developing countries. The different fuel and power technologies evaluated are at different levels of commercialization, with different application timings and scales in the future. Based on the multi-level perspective (MLP), the strategy of demand reduction and efficiency improvement is at the Meso-regime level and has not yet become mainstream. The strategy of land transportation electrification is shifting from the Meso-regime level to the Marco-landscape level. Alternative fuels for marine and aviation are only at the Micro-niche level, requiring deployment targets, regulatory changes, research and development programs and demonstration trials. For the first time, the IPCC separates the shipping and aviation sectors to discuss their GHG emissions trends and the decarbonization opportunities and challenges they face. In the medium to long term, all sectors need to emphasize the management of demand for transport services and the improvement of transport efficiency. Scenario literature suggests that global warming targets require economy-wide emission reduction measures, and the mitigation potential of transport electrification in particular depends heavily on the decarbonization of the power sector. Compared to 2010, transport-related emissions could increase by 65% in 2050 without mitigation measures while could reduce by 68% if the mitigation strategy is successfully deployed, which is also in line with the 1.5℃temperature rise target. These mitigation measures are of great significance for transportation in China to achieve emission peak and carbon neutrality.
The Working Group III of the Sixth Assessment Report (AR6) of IPCC conducted a comprehensive assessment of the low-carbon transition in global industry, including the status quo of carbon emissions, mitigation pathway, technology and policies, etc. Industry is the sector with fastest growth in carbon emissions since 2000. To achieve net zero CO2 emissions from the industrial sector is possible but challenging. It is needed to keep promoting energy efficiency and also deploying multiple available and emerging options on material efficiency, electrification and fuel switching, CO2 capture, utilization and storage (CCUS), etc. The conclusions of the report could be helpful for industry’s low-carbon transition in China.
In recent years, carbon capture, utilization and storage (CCUS), as one of the key technologies to address climate change, has attracted extensive attention from the international community. The Working Group III contribution to the IPCC Sixth Assessment Report (AR6) has repositioned CCUS, and assessed carbon capture and storage (CCS), carbon capture and utilization (CCU), bioenergy with carbon capture and storage (BECCS), direct air carbon capture and storage (DACCS) systematically and comprehensively, with focusing on mitigation potential and cost, comprehensive benefits and application prospects. The results show that CCUS is an indispensable combination of emission reduction technologies for the realization of global climate targets, which has the potential to achieve cumulative hundred-billion tons reduction effects by the middle of the 21st century. However, the current maturity of CCUS technology is overall at the demonstration stage and the cost is high, with mitigation potential to be further released. Considering CCUS can effectively reduce the risk of huge amount of stranded assets and has good social and environmental benefits, it’s necessary for China to regard CCUS as a strategic technology under the context of its own resource endowment. To promote the development of CCUS, China should coordinate top design, accelerate the construction of technology system, explore market incentive mechanism, and strengthen international cooperation.
Climate change is a significant challenge facing the world. It has become a general consensus that dealing with such a challenge requires international cooperation. The Sixth Assessment Report (AR6) of Working Group III (WGIII) of the Intergovernmental Panel on Climate Change (IPCC) presents an independent chapter (Chapter 14) which reviews the progress of international cooperation on climate change since the IPCC Fifth Assessment Report (AR5), and systematically assesses the progress based on the proposed evaluation system. According to the report, the most important progress in climate change cooperation since AR5 is the model of nationally determined contribution (NDC) global actions established under the Paris Agreement; in addition, various forms of international cooperation mechanisms have been established, among which the Climate Club has become a new hotspot for climate change cooperation research. As for the Paris Agreement, there are two opposite views in the international community on its effectiveness, and whether it can achieve its stated goals depends on the ability to strengthen the next step of global collective climate action goals and implementation.
Assessments of IPCC AR6 and SROCC show that the global warming rate in High Mountain (HM) regions has increased recently. Since the 1980s, the warming rate in the High Mountain Asia (HMA) has been significantly higher than the average of the global mountains and that in other high mountains. The warming is generally altitudinal dependent, but the mechanism keeps complex and there are large regional differences. Except for the Rocky Mountains, the warming magnitude in other high mountain areas will increase with altitude to varying degrees. Although the global annual precipitation in mountain areas in the past few decades has shown no obvious trend, it is projected that the annual precipitation in many Northern Hemisphere mountain regions will increase by 5%-20% by the end of the 21st century, with great spatial and temporal discrepancies of extreme rainfall. The frequency and intensity of extreme rainfall will increase over the Qinghai-Tibet Plateau and the Himalayas. The decrease of annual maximum snow water equivalent in mountains is stronger in the altitude zone that solid precipitation is transforming towards liquid precipitation, and the change of mountain snow in the future is not only related to the emission scenario, but also closely related to the altitude. Global mountain glacier mass loss from 2010 to 2019 was greater than that in any other decade since observational records began. Although the rate of mass loss in HMA is smaller, the total ice volume loss is second only to that in the Southern Andes among global main mountain regions. It is projected that mountain glacier retreat will continue for decades or hundreds of years in the future, and the corresponding contribution to the sea level rise will be the largest in HMA among the four HM regions. The permafrost temperature and the thickness of active layer in mountains have been found increased and decreased, respectively. In the future, mountain permafrost will become more unstable with continued and accelerated degradation. Even under the low greenhouse gases emission scenario, the permafrost area on the Qinghai-Tibetan Plateau is expected to decrease by 13.4% to 27.7% by the end of the 21st century. However, from the perspective of the completeness and confidence level of the above assessment, there are still huge gaps in observations and researches in the mountains.
The observing networks in mountains do not always follow standard observation procedures and are often not dense enough to capture fine-scale changes and potentially large-scale patterns. The discrepancies between satellite retrieval data and ground-based observations exist widely, especially for snow cover, which is still a recognized challenge. Therefore, immediate actions should be taken to strengthen the density of mountain observations, especially in three-dimensional space, in accordance with WMO standards, so as to improve the capacity of climate monitoring and services in mountain areas. In terms of information extraction from observations, refined, three-dimensional and accurate climate monitoring and assessment information is urgently needed to provide highly applicable scientific support for disaster management and climate change response.
Projections of future climate change are made through global climate models, regional climate models, or their simplified versions, which are dynamically consistent in the way of representing physical processes and hence link changes in mountains with large-scale atmospheric forcing. However, existing models that specialized for mountain studies usually cover only a single mountain range, and there have been no initiatives such as model inter-comparison programs or coordinated downscaling trials addressing problems existing in mountains climate change.
As a result, the direction of the future researches for mountain climate change lies, on the one hand, in the perspective of natural science, that is to continue to extract reliable information from observation data, support to improve the model resolution and simulation capability for complex underlying surfaces and quantify the contribution of mountain climate change in energy, water and carbon cycle and feedbacks from both macro and micro levels. On the other hand, from the perspective of supporting social sustainable development, to identify the climate change indicators that affect the stability of mountain society and ecosystem, supporting adaptation and mitigation of mountain climate change.
Based on current situation and development trend of wind power and photovoltaics Chinese Certified Emission Reduction (CCER) in China, a variety of policy scenarios were set up for CCER supply, offsetting and price formation and other key mechanisms. Under the background of the cancellation of wind power and photovoltaics price subsidies, a recursive dynamic Computable General Equilibrium (CGE) model with distinguished disaggregation in the electric power sector was developed to simulate the economic impacts of introducing wind power and photovoltaic CCER trading and offsetting mechanisms in the national carbon market. The results show that the introduction of wind power and photovoltaic CCER trading and offsetting mechanisms will reduce the carbon quota price and is also beneficial to ease the negative impact of the cancellation of wind power and photovoltaics price subsidies on these two electric power sectors, but it will weaken the carbon emission reduction effect of the national carbon market, and the effects will be more obvious with the increase of the total supply of CCER. After the introduction of wind power and photovoltaic CCER trading and offsetting mechanisms, industries with higher carbon emission intensity will choose to purchase more CCER, among which the thermal power industry will be the main buyer of CCER. If the register and approval of CCER will not be restarted in the future, the wind power industry will be the main beneficiary. However, if the register and approval of CCER can be restarted and its supply continues to increase year by year, both wind power and photovoltaic industries will benefit. Therefore, the total amount of initial carbon quota setting needs to be moderately tight when introducing CCER trading and offsetting mechanisms into national carbon market, China can consider restarting register and approval of CCER projects in the near future, but the upper limit of the allowable CCER settlement ratio should be reasonably set in combination with carbon emission reduction targets in order to avoid a great negative impact on the carbon emission reduction effect of the national carbon market.
