Total Mitigation Costs Research Articles

Opportunities beyond net-zero CO2 for cost-effective greenhouse gas mitigation in China

Achieving net-zero CO2 emissions is the current main focus of China’s carbon neutrality goal. However, non-CO2 greenhouse gases (GHGs) are more powerful climate forcers, making their emission reduction an opportunity to rapidly mitigate future warming. Here, we evaluate non-CO2 mitigation potentials, costs and climate benefits in the context of China’s carbon neutrality goals. The assessment is conducted by coupling the integrated assessment model GCAM with a climate emulator. The findings indicate that mitigation technologies can largely reduce fluorinated gas emissions from industrial sectors, but long-term non-CO2 reductions of energy sector activities rely heavily on fuel switching. Furthermore, the cumulative costs of deploying non-CO2 mitigation technologies are projected to be less than 10% of the total costs of achieving carbon neutrality from 2020 to 2060. If non-CO2 mitigation measures are included in the overall mitigation portfolio, the benefits of avoided warming would by far outweigh the total mitigation cost increase. Our results thus highlight that incorporating a wider suite of GHGs into climate change mitigation strategies can enhance the cost-effectiveness of mitigation efforts.

Accelerating carbon neutrality could help China's energy system align with below 1.5 °C

To support the achievement of the Paris Agreement's 1.5 °C global warming threshold, China aims to peak CO2 emissions before 2030 and achieve carbon neutrality before 2060. However, the specific carbon neutrality pathway remains to be designed. By applying a refined Chinese version of Global Change Analysis Model, this study examines implications of four illustrative carbon neutrality scenarios for aligning China's energy system with below 1.5 °C by 2100. The results feature a trade-off between China's ambition to transform its energy system toward mid-century and its reliance on carbon dioxide removal (CDR) after carbon neutrality. From a full time perspective until 2100, accelerating carbon neutrality could help China's energy system align with below 1.5 °C. Compared to a 2060 carbon neutrality scenario, a 2050 carbon neutrality scenario reduces China's total mitigation costs between 2021 and 2100 by 1.04% of GDP, reduces reliance on CDR by 36%, and provides some additional co-benefits, such as reduced air pollutants. However, special attention needs to be paid to the fact that accelerating carbon neutrality poses greater challenges and costs to China in overcoming development inertia and restructuring its energy system over the next 30–40 years. Compared to a 2060 carbon neutrality scenario, a 2050 scenario increases China's mitigation costs by a factor of 1.13 between 2021 and 2050. This study suggests through quantitative evidence that China could accelerate emissions reductions and energy system transformation to achieve carbon neutrality, based on its national circumstances and capabilities and international support.

The importance of health co-benefits under different climate policy cooperation frameworks

Reducing greenhouse gas emissions has the ‘co-benefit’ of also reducing air pollution and associated impacts on human health. Here, we incorporate health co-benefits into estimates of the optimal climate policy for three different climate policy regimes. The first fully internalizes the climate externality at the global level via a uniform carbon price (the ‘cooperative equilibrium’), thus minimizing total mitigation costs. The second connects to the concept of ‘common but differentiated responsibilities’ where nations coordinate their actions while accounting for different national capabilities considering socioeconomic conditions. The third assumes nations act only in their own self-interest. We find that air quality co-benefits motivate substantially reduced emissions under all three policy regimes, but that some form of global cooperation is required to prevent runaway temperature rise. However, co-benefits do warrant high levels of mitigation in certain regions even in the self-interested case, suggesting that air quality impacts may expand the range of possible policy outcomes whereby global temperatures do not increase unabated.

Carbon capture and storage in China’s power sector: Optimal planning under the 2 °C constraint

Carbon capture and storage (CCS) has been widely recognized as a key technology to reduce CO2 emissions in the power sector. China’s power sector needs to achieve large-scale emission reductions through CCS technologies to contribute to limiting the global temperature rise to less than 2℃. The best source–sink matching directly affects total mitigation costs for the power sector. However, China has not yet established an optimal CCS plan. This study evaluates the least-cost source–sink relationship and cluster development opportunities for CCS in China under the 2 °C constraint. The results show that 165 existing coal-fired power plants, which have an installed capacity of approximately 175 GW, need CCS retrofitting and can find a suitable CO2 storage site within an average radius of 115 km. The total captured CO2 is 17.42 billion tons in Northeast, North, East, Northwest, and South regions with the share of 10.79% (1.88 GtCO2), 31.29% (5.45 GtCO2), 35.25% (6.14GtCO2), 22.39% (3.90GtCO2), and 0.27% (47MtCO2), respectively. Approximately 90% of captured CO2 can be stored in the Songliao, Bohai Bay, and Subei basins. In addition, 23% of the emission reductions can be achieved through CO2-enhanced oil recovery. The total mitigation cost is USD 1212 billion and the revenue generated from CO2-enhanced oil recovery is USD 377 billion. Overall, it provides the least-cost source–sink layout and cluster development opportunities for CCS development under the 2 ℃ constraint, which can serve as a basis for large-scale CCS adoption in China.

Optimal planning to mitigate the impacts of roads on multiple species

Abstract Common worldwide and encroaching on even the most remote locations, roads negatively affects wildlife through habitat loss, fragmentation and direct mortality. Reducing these effects requires mitigation, including wildlife crossing structures and fencing. However, mitigation measures are expensive and vary in their success level, especially when constructed to meet the needs of several species. Moreover, mitigation planning rarely considers the needs of multiple species. As funds are limited, deciding where and how to act for the greatest return on investment is crucial. Combining decision theory with a metapopulation model, we determined the most cost‐effective actions mitigating the effects of roads on multiple species. The model is illustrated with two sets of species with varying of life‐history traits, from a diversity of taxonomic groups. We tested the cost‐effectiveness of spatially explicit combinations of three management options for each road section: (a) no mitigation, (b) fences without wildlife crossings, and (c) fences combined with wildlife crossings. We explored the trade‐offs between each population's probability of persistence and total mitigation cost, first on a per‐species basis and then considering all species. We then tested the cost‐effectiveness of different planning strategies: (a) single species, (b) two types of focal species based on different life‐history traits, and (c) comprehensive multispecies planning. Planning for the needs of all species at the same time (multispecies strategy) maximizes the number of persisting species and provides the most robust and cost‐effective planning strategy, while single‐species strategies were found to be inefficient. However, basing decisions on the focal species with the largest home range can provide reasonably cost‐effective results, but should be considered only when there is not enough time or money to collect the necessary information to perform a multispecies analysis. Synthesis and applications. Our model can be adapted to most road mitigation problems. It illustrates that the needs of multiple species should be considered to plan a cost‐effective road mitigation system. However, when resources are limited to plan for all species, those with larger home ranges should be used as reasonable proxies for other species.

Multi-objective analysis of the co-mitigation of CO2 and PM2.5 pollution by China's iron and steel industry

China has experienced serious fine particulate matter (PM2.5) pollution in recent years, and carbon dioxide (CO2) emissions must be controlled so that China can keep its pledge to reduce CO2 emissions by 2030. The iron and steel industry is energy intensive and contributes significantly to PM2.5 pollution in China. The simultaneous reduction of CO2 emissions and PM2.5 pollution while minimizing the total mitigation costs remains a crucial issue that must be resolved. Using a multi-objective analysis, we compared potential technology combinations based on various policy preferences and targets. Our results showed that policies designed to mitigate PM2.5 pollution have substantial co-benefits for CO2 emissions reductions. However, policies focused solely on reducing CO2 emissions fail to effectively reduce PM2.5. Furthermore, CO2 emissions reductions correspond to large financial costs, whereas PM2.5 pollution reductions are less expensive. Our results suggest that under limited budgets, decision makers should prioritize PM2.5 reductions because CO2 reductions may be simultaneously achieved. Achieving large decreases in CO2 emissions will require further technological innovations to reduce the cost threshold. Thus, China should focus on reducing PM pollution in the short term and prepare for the expected challenges associated with CO2 reductions in the future.

Substitutability and the Cost of Climate Mitigation Policy

We explore how and by how much the values of elasticities of substitution affect estimates of the cost of emissions reduction policies in computable general equilibrium (CGE) models. We use G-Cubed, an intertemporal CGE model, to carry out a sensitivity and factor decomposition analysis. The decomposition analysis determines the contributions of changes in average abatement costs and changes in baseline emissions to the change in total mitigation costs. The latter has not previously been considered. Average abatement cost rises non-linearly as elasticities are reduced. Changes in the substitution elasticities between capital, labor, energy, and materials have a greater impact on mitigation costs than do inter-fuel elasticities of substitution. The former have more effect on business as usual emissions and the latter on average abatement costs. As elasticities are reduced, business as usual emissions and GDP growth also decrease so that there is not much variation in the total costs of reaching a given target across the parameter space. Our results confirm that the cost of climate mitigation policy is at most a few percent of global GDP.

Economic tradeoffs in mitigation, due to different atmospheric lifetimes of CO2 and black carbon

Tradeoffs are examined between mitigating black carbon (BC) and carbon dioxide (CO2) for limiting peak global mean warming, using the following set of methods. A two-box climate model is used to simulate temperatures of the atmosphere and ocean for different rates of mitigation. Mitigation rates for BC and CO2 are characterized by respective timescales for e-folding reduction in emissions intensity of gross global product. There are respective emissions models that force the box model. Lastly there is a simple economics model, with cost of mitigation varying inversely with emission intensity.Constant mitigation timescale corresponds to mitigation at a constant annual rate, for example an e-folding timescale of 40years corresponds to 2.5% reduction each year. Discounted present cost depends only on respective mitigation timescale and respective mitigation cost at present levels of emission intensity. Least-cost mitigation is posed as choosing respective e-folding timescales, to minimize total mitigation cost under a temperature constraint (e.g. within 2°C above preindustrial). Peak warming is more sensitive to mitigation timescale for CO2 than for BC. Therefore rapid mitigation of CO2 emission intensity is essential to limiting peak warming, but simultaneous mitigation of BC can reduce total mitigation expenditure.

Reducing China’s road transport sector CO2 emissions to 2050: Technologies, costs and decomposition analysis

The growth of China’s road transport sector has driven huge increases in China’s oil demand and CO2 emissions over the last two decades, and these trends are likely to continue in the absence of specific measures to reduce the average carbon intensity of road vehicles. This paper describes a model, provided in full online, to undertake scenario analysis on the cost and CO2 emissions impact of substituting current vehicle drivetrain types with alternatives during the period 2010–2050. A detailed decomposition of the additional costs and CO2 emissions savings of each low-carbon vehicle type into their component parts is undertaken to calculate the marginal abatement cost of each vehicle and drivetrain type in 2050. The results indicate that passenger cars and heavy-duty trucks constitute the majority of future CO2 emissions savings potential, but that, using the central cost assumptions, alternative vehicle drivetrains are significantly more cost-effective for trucks than passenger cars. The low-carbon scenario sees demand for oil products (gasoline and diesel) more than 40% below the business-as-usual scenario in 2050. The total mitigation cost in 2050 is (US2010)$64 billion per year, or 1.3% of the total annual expenditure on road transport in China in 2050, using a discount rate of 5% to annualise vehicle purchase costs, although this cost increases with higher discount rates. A sensitivity analysis demonstrates that measures in addition to those assumed in the low-carbon scenario could achieve further emissions reductions, in some cases at negative costs. The availability and transparency of the model allows testing and development of a range of further scenarios and sensitivities, to aid in planning an optimal decarbonisation strategy for this highly carbon-intensive sector.

Deep CO2 emission reductions in a global bottom-up model approach

Most studies that explore deep GHG emission reduction scenarios assume that climate goals are reached by implementing least-cost emission mitigation options, typically by implementing a global carbon tax. Although such a method provides insight into total mitigation costs, it does not provide much information about how to achieve a transition towards a low-carbon energy system, which is of critical importance to achieving ambitious climate targets. To enable sensible deep emission reduction strategies, this study analysed the effectiveness of 16 specific mitigation measures on a global level up to 2050, by using an energy-system simulation model called TIMER. The measures range from specific energy efficiency measures, like banning traditional light bulbs and subsidizing electric vehicles, to broader policies like introducing a carbon tax in the electricity sector. All measures combined lead to global CO2 emission reductions ranging between 39% and 73% compared to baseline by 2050, depending on the inclusion of sectoral carbon taxes and the availability of carbon capture and storage (CCS) and nuclear power. Although the effectiveness of the measures differs largely across regions, this study indicates that measures aimed at stimulating low-carbon electricity production result in the highest reductions in all regions.Policy relevanceThe results of the calculations can be used to evaluate the effects of individual climate change mitigation measures and identify priorities in discussions on global and regional policies. The type of fragmented policy scenarios presented here could provide a relevant bottom-up alternative to cost-optimal implementation of policies driven by a carbon tax. We identify overlapping and even counter-productive climate policy measures through an analysis that presents the policy effectiveness by region, and by sector. The set of 16 policy measures addresses the largest emitting sectors and represents options that are often discussed as part of planned policies.

GHG Mitigation Potential and Cost in Tropical Forestry – Relative Role for Agroforestry

This paper summarizes studies of carbon mitigation potential (MP) and costs of forestry options in seven developing countries with a focus on the role of agroforestry. A common methodological approach known as comprehensive mitigation assessment process (COMAP) was used in each study to estimate the potential and costs between 2000 and 2030. The approach requires the projection of baseline and mitigation land-use scenarios derived from the demand for forest products and forestland for other uses such as agriculture and pasture. By using data on estimated carbon sequestration, emission avoidance, costs and benefits, the model enables one to estimate cost effectiveness indicators based on monetary benefit per t C, as well as estimates of total mitigation costs and potential when the activities are implemented at equilibrium level. The results show that about half the MP of 6.9 Gt C (an average of 223 Mt C per year) between 2000 and 2030 in the seven countries could be achieved at a negative cost, and the other half at costs not exceeding $100 per t C. Negative cost indicates that non-carbon revenue is sufficient to offset direct costs of about half of the options. The agroforestry options analyzed bear a significant proportion ofmore » the potential at medium to low cost per t C when compared to other options. The role of agroforestry in these countries varied between 6% and 21% of the MP, though the options are much more cost effective than most due to the low wage or opportunity cost of rural labor. Agroforestry options are attractive due to the large number of people and potential area currently engaged in agriculture, but they pose unique challenges for carbon and cost accounting due to the dispersed nature of agricultural activities in the tropics, as well as specific difficulties arising from requirements for monitoring, verification, leakage assessment and the establishment of credible baselines.« less