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Cumulative emissions budgets are increasingly being used by decision-makers and analysts to understand emissions reductions and associated transitions in the context of long-term goals such as limiting global mean temperature increase over the century to 1.5 or 2 °C. While previous studies have explored the implications of such budgets for the global economy, few studies have conducted regional- and national-level analyses. This paper explores budgets through 2050 consistent with the 1.5 and 2 °C long-term temperature goals in the context of the USA. We employ a state-level model of the USA embedded within a global human-Earth system model (GCAM-USA) to study the implications of such budgets for the US energy system. Our results show that achieving the stringent budgets entails accelerated deployment of energy conserving technology, almost complete decarbonization of the power sector, increased electrification of buildings and industrial end-use sectors, and decarbonization of transport employing a combination of electrification and the substitution of fossil fuels for bioenergy. We also find substantial state-level differences in the relative roles of these decarbonization strategies. Furthermore, our results highlight that increased ambition in the near term will be valuable in setting the stage for smoother transformations in the future to achieve stringent budgets. [ABSTRACT FROM AUTHOR]

Activities to reduce net greenhouse gas emissions by biological soil or forest carbon sequestration predominantly utilize currently known, readily implementable technologies. Many other greenhouse gas emission reduction options require future technological development or must wait for turnover of capital stock. Carbon sequestration options in soils and forests, while ready to go now, generally have a finite life, allowing use until other strategies are developed. This paper reports on an investigation of the competitiveness of biological carbon sequestration from a dynamic and multiple strategy viewpoint. Key factors affecting the competitiveness of terrestrial mitigation options are land availability and cost effectiveness relative to other options including CO2 capture and storage, energy efficiency improvements, fuel switching, and non-CO2 greenhouse gas emission reductions. The analysis results show that, at lower CO2 prices and in the near term, soil carbon and other agricultural/forestry options can be important bridges to the future, initially providing a substantial portion of attainable reductions in net greenhouse gas emissions, but with a limited role in later years. At higher CO2 prices, afforestation and biofuels are more dominant among terrestrial options to offset greenhouse gas emissions. But in the longer run, allowing for capital stock turnover, options to reduce greenhouse gas emissions from the energy system and biofuels provide an increasing share of potential reductions in total US greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Assesses the effectiveness of an emission reduction strategy as a means of mitigating the net impact of human activities on climate for the substitution of gas for coal. Key substances included in the substitution of gas for coal; Methane emissions from coal mining and natural gas loss; Time-dependent sensitivity of the benefits of fuel switching to key options in a given gas-for-coal substitution.

The relevance and cost-effectiveness are key criteria for policymakers to select appropriate policy and economic instruments for reducing carbon emissions. Here we assess the applicability of carbon finance instruments for the improvement in building energy efficiency by adopting the high efficiency standards as well as advanced energy supply systems, building on a case study in a northern city in China. We find that upgrading the current Chinese BEE standard to one of the best practices in the world coupled with the state-of-the-art energy supply system implies an abatement cost at 16US$/tCO, which is compatible with the international carbon market price. The institutional reorganization turns out to be indispensable to facilitate the implementation of the proposed scheme of local government-led energy efficiency programme in the form of programmatic CDM in China's buildings sector. We show that with international support such as carbon finance, the BEE improvement will facilitate city's transition to low-carbon supply in the longer term. More importantly, it is argued that demand-side energy performance improvement in buildings should be considered a prerequisite to shifting low-carbon energy supply technologies such as fuel-switching, renewable power generation and Carbon Capture and Storage to address climate mitigation in light of cost-effectiveness and environmental integrity. [ABSTRACT FROM AUTHOR]

India is perceived to be one of the most attractive Non-Annex I countries for CDM project development. There are more than 350 projects in the CDM pipeline, largely in the areas of renewable energy, energy efficiency in industries and fossil fuel switching. This paper examines the socio-economic component of sustainable development commitments of the CDM projects to see if they can make any impact on rural poverty in India, since the goal of poverty alleviation lies at the core of the country's development priorities. The study concludes that CDM is not contributing to rural poverty alleviation to any notable extent. Nearly all the projects have a business orientation and are not directed to the development of rural poor. Even the renewable energy projects will have limited role in up-liftment of the masses below poverty line due to their weak resource base. For CDM to emerge as a "win--win" strategy for poverty alleviation projects should be aimed at the rural communities and designed to accelerate agricultural growth in the rainfed regions of the country. [ABSTRACT FROM AUTHOR]

Abstract Carbon terrestrial sinks are often seen as a low-cost alternative to fuel switching and reduced fossil fuel use for lowering atmospheric CO2. To determine whether this is true for agriculture, one meta-regression analysis (52 studies, 536 observations) examines the costs of switching from conventional tillage to no-till, while another (51 studies, 374 observations) compares carbon accumulation under the two practices. Costs per ton of carbon uptake are determined by combining the two results. The viability of agricultural carbon sinks is found to vary by region and crop, with no-till representing a low-cost option in some regions (costs of less than $10 per tC), but a high-cost option in others (costs of 100$400 per tC). A particularly important finding is that no-till cultivation may store no carbon at all if measurements are taken at sufficient depth. In some circumstances no-till cultivation may yield a triple dividend of carbon storage, increased returns and reduced soil erosion, but in many others creating carbon offset credits in agricultural soils is not cost effective because reduced tillage practices store little or no carbon. [ABSTRACT FROM AUTHOR]

The expected growth in the demand for passenger and freight services exacerbates the challenges of reducing transport GHG emissions, especially as commercial low-carbon alternatives to petroleum fuels are limited for shipping, air and long-distance road travel. Biofuels can offer a pathway to significantly reduce emissions from these sectors, as they can easily substitute for conventional liquid fuels in internal combustion engines. In this paper, we assess the potential of bioenergy to reduce transport GHG emissions through an analysis leveraging various integrated assessment models and scenarios, as part of the 33rd Energy Modeling Forum study (EMF-33). We find that bioenergy can contribute a significant, albeit not dominant, proportion of energy supply to the future transport sector: in scenarios aiming to keep the temperature increase below 2 °C by the end of the twenty-first century, models project that in 2100 bioenergy can provide on average 42 EJ/yr (ranging from 5 to 85 EJ/yr) for transport (compared to 3.7 EJ in 2018), mainly through lignocellulosic fuels. This makes up 9–62% of final transport energy use. Only a small amount of bioenergy is projected to be used in transport through electricity and hydrogen pathways, with a larger role for biofuels in road passenger transport than in freight. The association of carbon capture and storage (CCS) with bioenergy technologies (BECCS) is a key determinant in the role of biofuels in transport, because of the competition for biomass feedstock to provide other final energy carriers along with carbon removal. Among models that consider CCS in the biofuel conversion process the average market share of biofuels is 21% in 2100 (ranging from 2 to 44%), compared to 10% (0–30%) for models that do not. Cumulative direct emissions from the transport sector account for half of the emission budget (from 306 to 776 out of 1,000 GtCO2). However, the carbon intensity of transport decreases as much as other energy sectors in 2100 when accounting for process emissions, including carbon removal from BECCS. Lignocellulosic fuels become more attractive for transport decarbonization if BECCS is not feasible for any energy sectors. Since global transport service demand increases and biomass supply is limited, its allocation to and within the transport sector is uncertain and sensitive to assumptions about political as well as technological and socioeconomic factors. [ABSTRACT FROM AUTHOR]

We quantify global and regional aggregate damages from global warming of 1.5 to 4 °C above pre-industrial levels using a well-established integrated assessment model, PAGE09. We find mean global aggregate damages in 2100 of 0.29% of GDP if global warming is limited to about 1.5 °C (90% confidence interval 0.09–0.60%) and 0.40% for 2 °C (range 0.12–0.91%). These are, respectively, 92% and 89% lower than mean losses of 3.67% of GDP (range 0.64–10.77%) associated with global warming of 4 °C. The net present value of global aggregate damages for the 2008–2200 period is estimated at $48.7 trillion for ~ 1.5 °C global warming (range $13–108 trillion) and $60.7 trillion for 2 °C (range $15–140 trillion). These are, respectively, 92% and 90% lower than the mean NPV of $591.7 trillion of GDP for 4 °C warming (range $70–1920 trillion). This leads to a mean social cost of CO2 emitted in 2020 of ~ $150 for 4 °C warming as compared to $30 at ~ 1.5 °C warming. The benefits of limiting warming to 1.5 °C rather than 2 °C might be underestimated since PAGE09 is not recalibrated to reflect the recent understanding of the full range of risks at 1.5 °C warming. [ABSTRACT FROM AUTHOR]

Most climate change mitigation scenarios rely on increased use of bioenergy to decarbonize the energy system. Here we use results from the 33rd Energy Modeling Forum study (EMF-33) to investigate projected international bioenergy trade for different integrated assessment models across several climate change mitigation scenarios. Results show that in scenarios with no climate policy, international bioenergy trade is likely to increase over time, and becomes even more important when climate targets are set. More stringent climate targets, however, do not necessarily imply greater bioenergy trade compared to weaker targets, as final energy demand may be reduced. However, the scaling up of bioenergy trade happens sooner and at a faster rate with increasing climate target stringency. Across models, for a scenario likely to achieve a 2 °C target, 10–45 EJ/year out of a total global bioenergy consumption of 72–214 EJ/year are expected to be traded across nine world regions by 2050. While this projection is greater than the present trade volumes of coal or natural gas, it remains below the present trade of crude oil. This growth in bioenergy trade largely replaces the trade in fossil fuels (especially oil) which is projected to decrease significantly over the twenty-first century. As climate change mitigation scenarios often show diversified energy systems, in which numerous world regions can act as bioenergy suppliers, the projections do not necessarily lead to energy security concerns. Nonetheless, rapid growth in the trade of bioenergy is projected in strict climate mitigation scenarios, raising questions about infrastructure, logistics, financing options, and global standards for bioenergy production and trade. [ABSTRACT FROM AUTHOR]

India's commitment to Paris Climate Change Agreement through its Nationally Determined Contribution (NDC) will require the energy system to gradually move away from fossil fuels. The current energy system is witnessing a transformation to achieve these through renewable energy targets and enhanced energy efficiency (EE) actions in all sectors. More stringent global GHG mitigation targets of 2 °C and well below 2 °C regimes would impose further challenges and uncertainties for the Indian energy systems. This paper provides a quantitative assessment using bottom-up optimization model (AIM/Enduse) to assess these until 2050 for meeting carbon mitigation commitments while achieving the national sustainable development goals. Energy transformation trajectories under five scenarios synchronized with climate mitigation regimes are explored—Business As Usual scenario (BAU), NDC scenario, 2 °C scenarios (early and late actions), and well below 2 °C scenario. The key results from the study include (a) coal-based power plants older than 30 years under NDC and older than 20 years for deeper CO2 mitigation will be stranded before their lifetime, (b) increase in renewables of up to 225–280 GW by 2050 will require battery storage with improved integrated smart grid infrastructure, (c) growth in nuclear to 27–32 GW by 2050 is dependent on nuclear supply availability, (d) gradual shift towards electrification in industry, building, and transport sectors, and (e) installation of CCS technologies in power and industry sectors. Cumulative investments of up to 6–8 trillion USD (approximately) will be required during 2015–2030 to implement the actions required to transform the current energy systems in India. [ABSTRACT FROM AUTHOR]

This research explores the agent dynamics, learning processes, and enabling conditions for the implementation of microscale win-win solutions that contribute to energy poverty eradication and climate resilience in a selection of low-income rural and peri-urban communities in India, Indonesia, and South Africa. We define these micro-solutions as energy-related interventions and resilience services or products—used at community, household, small production unit, or business level—that yield both economic and climatic gains. Our analysis identifies five elements critical for the robust design of these interventions: (i) The ability to collaborate and share different kinds of expertise with a range of networks operating at multiple levels of activity; (ii) The application of place-based systems-learning perspectives that enable project participants to integrate different types of solutions to meet different needs at the same time; (iii) The ability to yield tangible short-term benefits as part of long-term strategic visions and commitment; (iv) The use of novel technologies and financial instruments in ways that foreground the needs of poor populations; and (v) The inclusion and empowerment of economically marginalised groups through institutional and technological innovations and responsible business models. We conclude that the most critical aspect of successful micro win-win solutions is support for communities' own endogenous transformative capacities as this helps ensure that solutions are shared and continuously adapted to changing conditions over time. [ABSTRACT FROM AUTHOR]

Climate change may affect the US electricity system through changes in electricity demand, mediated by increases in average surface temperature, and through changes in electricity supply, mediated by changes in both surface temperature and regional water availability. By coupling projections from four general circulation models (GCMs) with a state-of-the-art US electricity system model—the Regional Energy Deployment System (ReEDS)—this study evaluates both the isolated and combined effects of different climate-mediated drivers of US electricity system change through 2050. Comparing results across climate models allows us to evaluate which effects are robust to uncertainty in projected climate outcomes. Comparing effects of different drivers in isolation and in combination allows us to determine the relative contributions of the climate-mediated effects on system evolution. Our results indicate that national-level energy and economic impacts are largely driven by increases in electricity demand that follow from a consistent increase in surface air temperature that is largely robust to the choice of climate model. Other electricity system changes can be equally or more significant in some regions, but these effects are more regionally variable, less significant when aggregated to the national scale, and less robust to the choice of climate model. The findings show that the impacts of climate change on the electricity system can be understood in terms of fewer drivers and with greater certainty at the national level than at the regional level. [ABSTRACT FROM AUTHOR]

Although the rapid fall in the costs of batteries has made electric vehicles (EVs) more affordable and boosted their sales, EVs still account for only a fraction of total car sales. In the last years, the battery costs of electric vehicles have dropped faster than previously estimated in the empirical literature. As a result, future cost projections have been adjusted. The larger than expected reduction in costs also shows the uncertainty of battery cost development, which will affect the success of a transition to low-carbon transport. Integrated assessment models show that reducing greenhouse gas emissions is more challenging in the transport sector than in other sectors. Switching to EVs could significantly reduce passenger road-transport emissions. In this study, we test the sensitivity of the projected sales of EVs to different battery costs and climate policy futures. The model suggests that the effectiveness of policy incentives will strongly depend on the battery floor costs, as EVs only gain significant shares (15% or more) of global car sales within our model framework when battery costs reach 100 $/kWh or less. We therefore conclude that besides the pace of the battery costs decline, which has been rapid in the last years, it is important to understand the lower boundary of battery costs for modelling long-term global energy transitions. [ABSTRACT FROM AUTHOR]

Banking and borrowing emission allowances provide temporal flexibility in cap-and-trade systems, which can enhance the economic efficiency of environmental policy while adhering to the same cumulative emission budget. This paper investigates the role of temporal ('when') flexibility from emission banking provisions under an economy-wide cap-and-trade policy in the USA. The current literature on meeting deep decarbonization targets almost exclusively assumes unlimited banking, which may bias policy recommendations and have important consequences for R&D prioritization and model development. Numerical experiments using the energy-economic model US Regional Energy, GHG, and Economy (US-REGEN) indicate that assumptions about banking materially impact cost and emission pathways in meeting long-term targets like 80% reductions by 2050 relative to 2005 levels. Given the stringency of long-run targets and convexity of marginal abatement costs, the cost-minimizing time path for mitigation with banking suggests that 2025 abatement should exceed the pledged level under the Paris Agreement (42% instead of 26-28%) to reduce future costs. Total policy costs are approximately 30% higher when banking is excluded; however, political economy barriers and uncertainty may limit the use of banking provisions despite their appeal on economic efficiency grounds. Banking on policy implementation with unlimited temporal flexibility may distort insights about the pace, extent, and economic impacts of future energy transitions associated with long-term abatement targets, especially for more stringent climate policies. [ABSTRACT FROM AUTHOR]

Output-based allocation (OBA) is one of the main options discussed for addressing carbon leakage in emissions trading systems. This paper studies how different OBA designs affect incentives on mitigation and trade in the cement sector. To do so, we develop an analytical model of sector emissions as a function of technical parameters representing abatement levers. We propose a specific design called hybrid OBA, and show that unlike the alternatives, it provides incentives for firms to reduce the carbon intensity of production without offshoring production. We assess the feasibility of hybrid OBA through expert interviews and find that the main barriers identified, including technical and administrative complexities, are manageable. However, hybrid OBA represents a mid-term solution until more robust anti-leakage measures can be introduced, because of two key limitations of OBA in general - it does not provide incentives to reduce the consumption of cement or to accelerate the development of radical low-carbon technologies, both of which are necessary to deliver deep decarbonisation. [ABSTRACT FROM AUTHOR]

Improved cookstoves have been identified in Mexico as a key opportunity to advance sustainable local development priorities in disadvantaged regions while mitigating climate change. This paper reviews the Patsari Cookstove Project initiated in 2003 by an NGO, Interdisciplinary Group on Appropriate Rural Technology (GIRA). The project applied an interdisciplinary and participative user-centered approach to disseminate improved cookstoves in rural Mexico, with a special focus on indigenous and poor rural communities. To date, GIRA and the Patsari Network have disseminated thousands of stoves using a 'training to trainers' model. Benefits from the project include tangible improvements in users' health, as well as savings in time and money expended on fuelwood procurement and use. The project has also documented substantive environmental benefits from significant mitigation of greenhouse gas (GHG) emissions associated with traditional open fires. To sustain scaling up efforts over the long-term, two networks have been created: The Patsari Network, which includes several organizations promoting Patsari stoves for household users, and the Tsiri Network, which supports local food security and the empowerment of indigenous women through the promotion of institutional cookstoves. Through appropriately designed and implemented local interventions, the project demonstrates that the goals of advancing sustainable local development in rural areas and climate change mitigation may not be contradictory, and may in fact reinforce one another. [ABSTRACT FROM AUTHOR]

Research has begun to uncover the extent that greenhouse gas emissions can be attributed to cities, as well as the scope for cities to contribute to emissions reduction. But assessments of the economics of urban climate mitigation are lacking, and are currently based on selective case studies or specific sectors. Further analysis is crucial to enable action at the urban level. Here we consider the investment needs associated with 11 clusters of low carbon measures that could be deployed across the world's urban areas in a way that is consistent with a broader 2°C target. Economic assessment of these low carbon measures finds that they could be deployed around the world with investments of c$1 trillion per year between 2015 and 2050 (equivalent to 1.3% of global GDP in 2014). When the direct savings that emerge from these measures due to avoided energy costs are considered, under the central scenario these investments have a net present value of c$16.6 trillion USD in the period to 2050. However, discount rates, energy prices and rates of technological learning are key to the economic feasibility of climate action, with the NPV of these measures ranging from -$1.1 trillion USD to $65.2 trillion USD under different conditions. [ABSTRACT FROM AUTHOR]

The magnitude and character of the global resource base of fossil fuels is a key determinant of the evolution of the future global energy system and corresponding fossil fuel carbon emissions. What is less well understood is the potential magnitude of impact of the availability of fossil fuels, due to the interaction with biomass energy, on agriculture, land use, ecosystems and therefore carbon emissions from land-use change. This paper explores these links and implications. We show that if oil resources are limited, then the consequently higher price for liquids induces both the use of coal-to-liquids technology deployment, but also enhanced production of bioenergy crops particularly in a business-as-usual scenario. This in turn implies greater pressure to convert unmanaged ecosystems to produce bioenergy, and higher rates of terrestrial carbon emissions from land use. [ABSTRACT FROM AUTHOR]

A zero-carbon society requires dramatic change everywhere including in buildings, a large and politically sensitive sector. Technical possibilities exist but implementation is slow. Policies include many hard-to-evaluate regulations and may suffer from rebound mechanisms. We use dynamic econometric analysis of European macro data for the period 1990–2018 to systematically examine the importance of changes in energy prices and income on residential energy demand. We find a long-run price elasticity of −0.5. The total long-run income elasticity is around 0.9, but if we control for the increase in income that goes towards larger homes and other factors, the income elasticity is 0.2. These findings have practical implications for climate policy and the EU buildings and energy policy framework. [ABSTRACT FROM AUTHOR]

This paper analyses the technology choices of countries that prioritized transport as a sector in Asia under the Technology Needs Assessment project. The countries used a wide variety of criteria to prioritize technologies which were related to the benefits technologies would provide, costs of technologies and availability of technology charactersitics. Non-motorized transport, mass transit and technologies that improve vehicle energy efficiency emerged as the three most preferred technology choices for the countries. These technology choices can be appropriate candidates for nationally appropriate mitigations actions (NAMA) given their strong contribution for developmentand therefore a methodology based on input-output decomposition analysis isproposed for analysing economy wide CO emissions reductions. The methodologyhas been applied for the transport sector of Lebanon where alternative fuels,improvement to cars (private and taxis) and buses for public transport were prioritized by stakeholders. The economy-wide CO emission reduce by 2,269 thousand tons by 2020 if the prioritized technologies are implemented in Lebanon. Fuel mix effect and structural effect would reduce CO emission by 2,611 thousand tons, while the final demand effect would increase the CO emission by 342 thousand tons. [ABSTRACT FROM AUTHOR]

Cap-and-trade, a regulatory instrument widely used to constrain greenhouse gas and other pollution, has recently been criticized for producing only small amounts of intended emission reductions. This paper looks at the empirical record of cap-and-trade since the beginning in 1995, and shows that emission targets have almost always been easier and cheaper to reach than expected. The five main reasons are generous targets, changes in economic output, fuel price movements, innovation, and complementary emission reduction policies. Overall, this failure to predict mitigation potentials may relate to a psychological 'end of history bias,' whereby policymakers, industry, and analysts think that less change will happen in the future than has demonstrably happened in the past. Consequently, more abatement is possible and at lower costs than generally thought, rendering the prices of emission permits hard to predict. For climate research, the findings imply that emission scenarios assuming ever-increasing pollution prices may benefit from integrating recent experience with cap-and-trade regulations. In policy terms, mechanisms such as floor prices need to be considered to guarantee emission reductions under uncertainty. [ABSTRACT FROM AUTHOR]

This paper analyses factors that contributed to the evolution of SO, NO and CO emissions in Europe from 1960 to 2010. Historical energy balances, along with population and economic growth data, are used to quantify the impacts of major determinants of changing emission levels, including energy intensity, conversion efficiency, fuel mix, and pollution control. Time series of emission levels are compared for countries in Western and Eastern Europe, throwing light on differences in the importance of particular emission-driving forces. Three quarters of the decline in SO emissions in Western Europe resulted from a combination of reduced energy intensity and improved fuel mix, while dedicated end-of-pipe abatement measures played a dominant role in the reduction of NO emissions. The increase in atmospheric emissions in Eastern Europe through the mid-1990s was associated with the growth of energy-intensive industries, which off-setted the positive impact of better fuel quality and changes in fuel mix. A continuous decrease in energy intensity and higher conversion efficiencies have been the main factors responsible for the moderate rate of growth of European CO emissions. [ABSTRACT FROM AUTHOR]

Carbon Capture and Storage (CCS) can be a valuable CO mitigation option, but what role CCS will play in the future is uncertain. In this paper we analyze the results of different integrated assessment models (IAMs) taking part in the 27th round of the Energy Modeling Forum (EMF) with respect to the role of CCS in long term mitigation scenarios. Specifically we look into the use of CCS as a function of time, mitigation targets, availability of renewables and its use with different fuels. Furthermore, we explore the possibility to relate model results to general and CCS specific model assumptions. The results show a wide range of cumulative capture in the 2010-2100 period (600-3050 GtCO), but the fact that no model projects less than 600 GtCO indicates that CCS is considered to be important by all these models. Interestingly, CCS storage rates are often projected to be still increasing in the second half of this century. Depending on the scenario, at least six out of eight, up to all models show higher storage rates in 2100 than in 2050. CCS shares in cumulative primary energy use are in most models increasing with the stringency of the target or under conservative availability of renewables. The strong variations of CCS deployment projection rates could not be related to the reported differences in the assumptions of the models by means of a cross-model comparison in this sample. [ABSTRACT FROM AUTHOR]

Based on a large number of energy-economic and integrated assessment models, the Energy Modeling Forum (EMF) 27 study systematically explores the implications of technology cost and availability for feasibility and macroeconomic costs of energy system transformations toward climate stabilization. At the highest level, the technology strategy articulated in all the scenarios in EMF27 includes three elements: decarbonization of energy supply, increasing the use of low-carbon energy carriers in end-use, and reduction of energy use. The way that the scenarios differ is in the degree to which these different elements of strategy are implemented, the timing of those implementations, and the associated macroeconomic costs. The study also discusses the value of individual technologies for achieving climate stabilization. A robust finding is that the unavailability of carbon capture and storage and limited availability of bioenergy have the largest impact on feasibility and macroeconomic costs for stabilizing atmospheric concentrations at low levels, mostly because of their combined ability to remove carbon from the atmosphere. Constraining options in the electric sector such as nuclear power, wind and solar energy in contrast has a much smaller impact on the cost of mitigation. [ABSTRACT FROM AUTHOR]

This paper analyzes the role of transport electrification in the broader context of energy system transformation and climate stabilization. As part of the EMF27 model inter-comparison exercise, we employ the MESSAGE integrated assessment modeling framework to conduct a systematic variation of availability, cost, and performance of particular energy supply technologies, thereby deriving implications for feasibility of climate stabilization goals and the associated costs of mitigation. In addition, we explore a wide range of assumptions regarding the potential degree of electrification of the transportation sector. These analyses allow us to (i) test the extent to which the feasible attainment of stringent climate policy targets depends on transport electrification, and (ii) assess the far-reaching impacts that transport electrification could have throughout the rest of the energy system. A detailed analysis of the transition to electricity within the transport sector is not conducted. Our results indicate that while a low-carbon transport system built upon conventional liquid-based fuel delivery infrastructures is destined to become increasingly reliant on biofuels and synthetic liquids, electrification opens up a door through which nuclear energy and non-biomass renewables can flow. The latter has important implications for mitigation costs. [ABSTRACT FROM AUTHOR]

This paper evaluated the impacts of climate change mitigation technology options on CO emission reductions and the effects of model representations regarding renewable intermittency on the assessment of reduction by using a world energy systems model. First, different diffusion scenarios for carbon dioxide capture and storage (CCS), nuclear power, and wind power and solar PV are selected from EMF27 scenarios to analyze their impacts on CO emission reductions. These technologies are important for reducing CO intensity of electricity, and the impacts of their diffusion levels on mitigation costs are significant, according to the analyses. Availability of CCS in particular, among the three kinds of technologies, has a large impact on the marginal CO abatement cost. In order to analyze effects of model representations regarding renewables intermittency, four different representations are assumed within the model. A simplistic model representation that does not take into consideration the intermittency of wind power and solar PV evaluates larger contributions of the energy sources than those evaluated by a model representation that takes intermittency into consideration. Appropriate consideration of renewables intermittency within global energy systems models will be important for realistic evaluations of climate change mitigation scenarios. [ABSTRACT FROM AUTHOR]

Carbon terrestrial sinks are often seen as a low-cost alternative to fuel switching and reduced fossil fuel use for lowering atmospheric C[O.sub.2]. To determine whether this is true for agriculture, one meta-regression analysis (52 studies, 536 observations) examines the costs of switching from conventional tillage to no-till, while another (51 studies, 374 observations) compares carbon accumulation under the two practices. Costs per ton of carbon uptake are determined by combining the two results. The viability of agricultural carbon sinks is found to vary by region and crop, with no-till representing a low-cost option in some regions (costs of less than $10 per tC), but a high-cost option in others (costs of 100-$400 per tC). A particularly important finding is that no-till cultivation may store no carbon at all if measurements are taken at sufficient depth. In some circumstances no-till cultivation may yield a 'triple dividend' of carbon storage, increased returns and reduced soil erosion, but in many others creating carbon offset credits in agricultural soils is not cost effective because reduced tillage practices store little or no carbon.

We explore allowable leakage for carbon capture and geological storage to be consistent with maximum global warming targets of 2.5 and 3 °C by 2100. Given plausible fossil fuel use and carbon capture and storage scenarios, and based on modeling of time-dependent leakage of CO, we employ a climate model to calculate the long-term temperature response of CO emissions. We assume that half of the stored CO is permanently trapped by fast mechanisms. If 40 % of global CO emissions are stored in the second half of this century, the temperature effect of escaped CO is too small to compromise a 2.5 °C target. If 80 % of CO is captured, escaped CO must peak 300 years or later for consistency with this climate target. Due to much more CO stored for the 3 than the 2.5 °C target, quality of storage becomes more important. Thus for the 3 °C target escaped CO must peak 400 years or later in the 40 % scenario, and 3000 years or later in the 80 % scenario. Consequently CO escaped from geological storage can compromise the less stringent 3 °C target in the long-run if most of global CO emissions have been stored. If less CO is stored only a very high escape scenario can compromise the more stringent 2.5 °C target. For the two remaining combinations of storage scenarios and climate targets, leakage must be high to compromise these climate targets. [ABSTRACT FROM AUTHOR]

This paper synthesizes the results from the model intercomparison exercise among regionalized global energy-economy models conducted in the context of the RECIPE project. The economic adjustment effects of long-term climate policy are investigated based on the cross-comparison of the intertemporal optimization models ReMIND-R and WITCH as well as the recursive dynamic computable general equilibrium model IMACLIM-R. A number of robust findings emerge. If the international community takes immediate action to mitigate climate change, the costs of stabilizing atmospheric CO concentrations at 450 ppm (roughly 530-550 ppm-e) discounted at 3% are estimated to be 1.4% or lower of global consumption over the twenty-first century. Second best settings with either a delay in climate policy or restrictions to the deployment of low-carbon technologies can result in substantial increases of mitigation costs. A delay of global climate policy until 2030 would render the 450 ppm target unachievable. Renewables and CCS are found to be the most critical mitigation technologies, and all models project a rapid switch of investments away from freely emitting energy conversion technologies towards renewables, CCS and nuclear. Concerning end use sectors, the models consistently show an almost full scale decarbonization of the electricity sector by the middle of the twenty-first century, while the decarbonization of non-electric energy demand, in particular in the transport sector remains incomplete in all mitigation scenarios. The results suggest that assumptions about low-carbon alternatives for non-electric energy demand are of key importance for the costs and achievability of very low stabilization scenarios. [ABSTRACT FROM AUTHOR]

This paper assesses the economic value associated with the development of various low-carbon technologies in the context of climate stabilization. We analyze the impact of restrictions on the development of specific mitigation technologies, comparing three integrated assessment models used in the RECIPE comparison exercise. Our results indicate that the diversification of the carbon mitigation portfolio is an important determinant of the feasibility of climate policy. Foregoing specific low carbon technologies raises the cost of achieving the climate policy, though at different rates. CCS and renewables are shown to have the highest value, given their flexibility and wide coverage. The costs associated with technology failure are shown to be related to the role that each technology plays in the stabilization scenario, but also to the expectations about their technological progress. In particular, the costs of restriction of mature technologies can be partly compensated by more innovation and technological advancement. [ABSTRACT FROM AUTHOR]

Legislation to decarbonise energy systems within overall greenhouse gas reduction targets represents an immense and unprecedented energy policy challenge. However there is a dichotomy between this level of policy ambition and prior modelling studies that find such targets economically, technologically and socially feasible under idealised - first-best policies. This paper makes a significant contribution to current analytical efforts to account for realistic - second-best climate mitigation policy implementation. This is achieved via a technical classification of secondbest common mode issues at a detailed national level: both internal (behavioural change, infrastructure implementation) and external (new technologies, resource availability). Under a combinatory second-best scenario, meeting targets greater than a 70% reduction in CO by 2050 entail costs above a subjective barrier of 1% of GDP, while extreme mitigation scenarios (>90% CO reduction) are infeasible. These high costs are equally due to disappointing progress in behavioural and technological mitigation efforts. Expensive second-best mitigation scenarios can still rely on extreme assumptions including the full deployment of the UK's offshore wind resource or the complete diffusion of energy efficiency measures in end-use sectors. By demonstrating the fragilities of a low carbon energy system pathway, policy makers can explore protective and proactive strategies to ensure targets can actually be met. Additionally, systematic analysis of failure in stringent long term decarbonisation scenarios teaches energy analysts about the trade-offs in model efficacy vs. confidence. [ABSTRACT FROM AUTHOR]

Using the mathematical formalism of the Brazilian Proposal to the IPCC, we analyse eight power technologies with regard to their past and potential future contributions to global warming. Taking into account detailed bottom-up technology characteristics we define the mitigation potential of each technology in terms of avoided temperature increase by comparing a 'coal-only' reference scenario and an alternative low-carbon scenario. Future mitigation potentials are mainly determined by the magnitude of installed capacity and the temporal deployment profile. A general conclusion is that early technology deployment matters, at least within a period of 50-100 years. Our results conclusively show that avoided temperature increase is a better proxy for comparing technologies with regard to their impact on climate change, and that numerous short-term comparisons based on annual or even cumulative emissions may be misleading. Thus, our results support and extend the policy relevance of the Brazilian Proposal in the sense that not only comparisons between countries, but also comparisons between technologies could be undertaken on the basis of avoided temperature increase rather than on the basis of annual emissions as is practiced today. [ABSTRACT FROM AUTHOR]

In this paper we argue that the financial provisions of the Copenhagen Accord, if used primarily to mitigate greenhouse gas (GHGs) emissions, could compensate the lack of more energetic action on the domestic mitigation side. In order to maximize the mitigation potential, the Copenhagen Green Climate Fund (CGCF) should be transformed into the International Bank for Emissions Allowance Acquisition (IBEAA) envisaged by Bradford (). We estimate that 50 percent of the CGCF in 2020 (50 US billions) could finance from 2.1 to 3.3 Gt CO2-eq emission reductions, depending on the domestic mitigation effort of Annex I and Non-Annex I countries. We construct a matrix that shows the level of GHGs emissions in 2020 under all possible combinations of abatement pledges and international mitigation financing, thus highlighting a rich set of options to reach the same level of GHGs emissions in 2020. [ABSTRACT FROM AUTHOR]

Climate change is an issue of great importance for human rights, public health, and socioeconomic equity because of its diverse consequences overall as well as its disproportionate impact on vulnerable and socially marginalized populations. Vulnerability to climate change is determined by a community's ability to anticipate, cope with, resist, and recover from the impact of major weather events. Climate change will affect industrial and agricultural sectors, as well as transportation, health, and energy infrastructure. These shifts will have significant health and economic consequences for diverse communities throughout California. Without proactive policies to address these equity concerns, climate change will likely reinforce and amplify current as well as future socioeconomic disparities, leaving low-income, minority, and politically marginalized groups with fewer economic opportunities and more environmental and health burdens. This review explores the disproportionate impacts of climate change on vulnerable groups in California and investigates the costs and benefits of the climate change mitigation strategies specified for implementation in the California Global Warming Solutions Act of 2006 (AB 32). Lastly, knowledge gaps, future research priorities, and policy implications are identified. [ABSTRACT FROM AUTHOR]

This study simulates the impacts of higher temperatures resulting from anthropogenic climate change on residential electricity consumption for California. Flexible temperature response functions are estimated by climate zone, which allow for differential effects of days in different temperature bins on households' electricity consumption. The estimation uses a comprehensive household level dataset of electricity bills for California's three investor-owned utilities (Pacific Gas and Electric, San Diego Gas and Electric, and Southern California Edison). The results suggest that the temperature response varies greatly across climate zones. Simulation results using a downscaled version of the National Center for Atmospheric Research global circulation model suggest that holding population constant, total consumption for the households considered may increase by up to 55% by the end of the century. The study further simulates the impacts of higher electricity prices and different scenarios of population growth. Finally, simulations were conducted consistent with higher adoption of cooling equipment in areas which are not yet saturated, as well as gains in efficiency due to aggressive energy efficiency policies. [ABSTRACT FROM AUTHOR]

Representative Concentration Pathway (RCP) 4.5 is a scenario that stabilizes radiative forcing at 4.5 W m in the year 2100 without ever exceeding that value. Simulated with the Global Change Assessment Model (GCAM), RCP4.5 includes long-term, global emissions of greenhouse gases, short-lived species, and land-use-land-cover in a global economic framework. RCP4.5 was updated from earlier GCAM scenarios to incorporate historical emissions and land cover information common to the RCP process and follows a cost-minimizing pathway to reach the target radiative forcing. The imperative to limit emissions in order to reach this target drives changes in the energy system, including shifts to electricity, to lower emissions energy technologies and to the deployment of carbon capture and geologic storage technology. In addition, the RCP4.5 emissions price also applies to land use emissions; as a result, forest lands expand from their present day extent. The simulated future emissions and land use were downscaled from the regional simulation to a grid to facilitate transfer to climate models. While there are many alternative pathways to achieve a radiative forcing level of 4.5 W m, the application of the RCP4.5 provides a common platform for climate models to explore the climate system response to stabilizing the anthropogenic components of radiative forcing. [ABSTRACT FROM AUTHOR]

This paper summarizes the main characteristics of the RCP8.5 scenario. The RCP8.5 combines assumptions about high population and relatively slow income growth with modest rates of technological change and energy intensity improvements, leading in the long term to high energy demand and GHG emissions in absence of climate change policies. Compared to the total set of Representative Concentration Pathways (RCPs), RCP8.5 thus corresponds to the pathway with the highest greenhouse gas emissions. Using the IIASA Integrated Assessment Framework and the MESSAGE model for the development of the RCP8.5, we focus in this paper on two important extensions compared to earlier scenarios: 1) the development of spatially explicit air pollution projections, and 2) enhancements in the land-use and land-cover change projections. In addition, we explore scenario variants that use RCP8.5 as a baseline, and assume different degrees of greenhouse gas mitigation policies to reduce radiative forcing. Based on our modeling framework, we find it technically possible to limit forcing from RCP8.5 to lower levels comparable to the other RCPs (2.6 to 6 W/m). Our scenario analysis further indicates that climate policy-induced changes of global energy supply and demand may lead to significant co-benefits for other policy priorities, such as local air pollution. [ABSTRACT FROM AUTHOR]

Cities are particularly vulnerable to climate change and climate extremes in part because they concentrate many activities, people and wealth in limited areas. As a result they represent an important scale for assessment and understanding of climate change impacts. This paper provides a conceptual and methodological framework for urban economic impact assessment of climate change. The focus of the paper is on model-based analysis of future scenarios, including a framing of uncertainty for these projections, as one valuable input into the decision-making process. The paper highlights the main assessment difficulties, methods and tools, and selected examples across these areas. A number of challenges are unique to climate change impact assessment and others are unique to the problem of working at local scales. The paper also identifies the need for additional research, including the need for more integrated and systemic approaches to address climate change as a part of the urban development challenge as well as the need to assess the economic impacts of climate change and response policy at local scale. [ABSTRACT FROM AUTHOR]

The relationship between R&D investments and technical change is inherently uncertain. In this paper we combine economics and decision analysis to incorporate the uncertainty of technical change into climate change policy analysis. We present the results of an expert elicitation on the prospects for technical change in carbon capture and storage. We find a significant amount of disagreement between experts, even over the most mature technology; and this disagreement is most pronounced in regards to cost estimates. We then use the results of the expert elicitations as inputs to the MiniCAM integrated assessment model, to derive probabilistic information about the impacts of R&D investments on the costs of emissions abatement. We conclude that we need to gather more information about the technical and societal potential for Carbon Storage; cost differences among the different capture technologies play a relatively smaller role. [ABSTRACT FROM AUTHOR]

This article discusses how renewable and low-carbon energies can serve as mitigation options of climate change in China’s power sector. Our study is based on scenarios developed in PowerPlan, a bottom-up model simulating a countries’ power sector and its emissions. We first adjusted the model to China’s present-day economy and power sector. We then developed different scenarios based on story lines for possible future developments in China. We simulated China’s carbon-based electricity production system of today and possible future transitions towards a low-carbon system relying on renewable and low-carbon energies. In our analysis, we compare the business-as-usual scenarios with more sustainable energy scenarios. We found that by increasing the share of renewable and nuclear energies to different levels, between 17% and 57% of all CO2 emissions from the power sector could be avoided by 2030 compared to the business-as-usual scenario. We also found that electricity generation costs increase when more sustainable power plants are installed. As a conclusion, China has two options: choosing for high climate change mitigation and high costs or choosing for moderate climate change mitigation and moderate costs. In case high climate change mitigation will be chosen, development assistance is likely to be needed to cover the costs. [ABSTRACT FROM AUTHOR]

This paper assesses regional abatement action and costs for two scenarios in which atmospheric greenhouse gas concentrations stabilise at 450 and 550 ppm CO2-equivalent. It evaluates two allocation schemes: Multi-Stage and Contraction & Convergence. It was found that abatement costs as percentages of GDP vary significantly by region, with high costs for the Middle East and the former Soviet Union, medium costs for the OECD regions and low costs or even gains for (other) developing regions. In addition to the abatement costs they incur, fossil-fuel-exporting regions are also likely to be affected by losses of coal and oil exports while the former Soviet Union and South America could experience increased bio-energy exports. Especially in the former Soviet Union and Asia, non-CO2 abatement options are important in the short term in reducing their emissions. Carbon capture and storage, energy efficiency improvements, bio-energy use and the use of renewables dominate reductions in the long term in all regions. It was found that the regional costs are influenced more by the assumed stabilisation level and baseline scenario than by the allocation regimes explored or the assumptions for different technologies. [ABSTRACT FROM AUTHOR]

This article presents an analytical framework for analyzing Clean Development Mechanism (CDM) projects in terms of their contribution to employment generation, equal distribution of CDM returns, and improvement of local air quality. It assesses 16 officially registered CDM projects with regard to whether they fulfill the two objectives required by the Kyoto Protocol: greenhouse gas emission reductions and contribution to sustainable development in the host country. While a large part (72%) of the total portfolio's expected Certified Emission Reductions (CERs) are likely to represent real and measurable emission reductions, less than 1% are likely to contribute significantly to sustainable development in the host country. According to our analysis, there are currently no UNFCCC registered CDM projects that are likely to fulfill the Kyoto Protocol's twofold objective of simultaneously delivering greenhouse gas (GHG) emission reduction and contributing to sustainable development. [ABSTRACT FROM AUTHOR]

Terrestrial carbon sinks and sources were introduced into climate change mitigation related policy relatively late in the design of the architecture of those policies. Much literature addresses how terrestrial sources and sinks differ from emissions from fossil fuel combustion and, hence, is a possible justification for differential treatment of them in policy design. Late introduction in climate policy discussions and perceived differences appear to have resulted in very different policy approaches for sinks versus fossil emission sources. The attempt to differentiate has generated complexity in policy design and likely inefficiency in the operation of these policies. We review these issues and find that the characteristics claimed to apply to sinks apply as well to fossil sources, and differences that do exist are often more a matter of degree than of kind. Because cap-and-trade has gained momentum as the instrument of choice to control fossil emissions, we use as a starting point, how such a cap-and-trade system could be altered to include terrestrial carbon sinks and sources. [ABSTRACT FROM AUTHOR]

Vulnerability is an emerging concept for climate science and policy. Over the past decade, efforts to assess vulnerability to climate change triggered a process of theory development and assessment practice, which is reflected in the reports of the Intergovernmental Panel on Climate Change (IPCC). This paper reviews the historical development of the conceptual ideas underpinning assessments of vulnerability to climate change. We distinguish climate impact assessment, first- and second-generation vulnerability assessment, and adaptation policy assessment. The different generations of assessments are described by means of a conceptual framework that defines key concepts of the assessment and their analytical relationships. The purpose of this conceptual framework is two-fold: first, to present a consistent visual glossary of the main concepts underlying the IPCC approach to vulnerability and its assessment; second, to show the evolution of vulnerability assessments. This evolution is characterized by the progressive inclusion of non-climatic determinants of vulnerability to climate change, including adaptive capacity, and the shift from estimating expected damages to attempting to reduce them. We hope that this paper improves the understanding of the main approaches to climate change vulnerability assessment and their evolution, not only within the climate change community but also among researchers from other scientific communities, who are sometimes puzzled by the unfamiliar use of technical terms in the context of climate change. [ABSTRACT FROM AUTHOR]

We estimate the domestic environmental and health benefits of exploiting China's energy-related CDM potential. Exploiting the CDM potential may save between 3,000 and 40,000 lives annually. Additional gains are estimated to reach upwards from 1 billion RMB annually. The key to these gains is the fact that actions and measures to reduce CO2 emissions also reduce emissions of TSP and SO2. In our estimate, exploiting the CDM-potential will cut SO2-emissions by between one-half and three million tons annually. To arrive at these conclusions we synthesize a significant body of recent research on co-benefits of climate abatement in China. [ABSTRACT FROM AUTHOR]

The importance of sulfur dioxide emissions for climate change is now established, although substantial uncertainties remain. This paper presents projections for future sulfur dioxide emissions using the MiniCAM integrated assessment model. A new income-based parameterization for future sulfur dioxide emissions controls is developed based on purchasing power parity (PPP) income estimates and historical trends related to the implementation of sulfur emissions limitations. This parameterization is then used to produce sulfur dioxide emissions trajectories for the set of scenarios developed for the Special Report on Emission Scenarios (SRES). We use the SRES methodology to produce harmonized SRES scenarios using the latest version of the MiniCAM model. The implications, and requirements, for integrated assessment modeling of sulfur dioxide emissions are discussed. We find that sulfur emissions eventually decline over the next century under a wide set of assumptions. These emission reductions result from a combination of emission controls, the adoption of advanced electric technologies, and a shift away from the direct end use of coal with increasing income levels. Only under a scenario where incomes in developing regions increase slowly do global emission levels remain at close to present levels over the next century. Under a climate policy that limits emissions of carbon dioxide, sulfur dioxide emissions fall in a relatively narrow range. In most cases, the relative climatic effect of sulfur dioxide emissions decreases dramatically to a point where sulfur dioxide is only a minor component of climate forcing by the end of the century. Ecological effects of sulfur dioxide, however, could be significant in some developing regions for many decades to come. [ABSTRACT FROM AUTHOR]

Afforestation is considered an important option for mitigation of greenhouse gas emissions. Recently, plantation projects have been suggested for inclusion under the Clean Development Mechanism. While considered a cheap option, significant uncertainties make it difficult to determine the (net) carbon benefits and profitability of forestry projects. The current uncertainties about the regulatory framework of the CDM and the environmental and economic performance of plantation forestry could create uncertainties with respect to the additionality of such projects and thus their acceptance under the mechanism. Six plantation forestry projects that were proposed in Brazil have been used as cases to study sources of uncertainty for carbon benefits and economics for such projects. These cases vary widely in terms of productivity and products delivered. A quantitative model for calculating greenhouse gas balances and financial benefits and costs, taking a broad range of variables into account, was developed. Data from the developers of the proposed projects was used as main source material. Subsequently, scenario''s were evaluated, containing different and realistic options for baseline vegetation, carbon crediting systems and CDM modalities, fluctuations in product prices, discount rates and carbon prices. The real cost of combined carbon sequestration and substitution for the case projects was below $3 per ton of carbon avoided, when based exclusively on data supplied by project developers. However, potential variations in carbon impact and costs based on scenario options were very large. Different baseline vegetation or adopting a different discount rate cause carbon credits to vary by as much as an order of magnitude. Different carbon crediting systems or fluctuations in (commodity) product prices cause variations up to 200% in carbon credits and NPV. This makes the additionality of such projects difficult to determine. Five of the six case projects seem uneligible for development under the CDM. A critical attitude towards the use of plantation projects under the CDM seems justified. [ABSTRACT FROM AUTHOR]

This paper presents an approach to estimating world-regional carbon mitigation cost functions for the years 2020, 2050, and 2100. The approach explicitly includes uncertainty surrounding such carbon reduction costs. It is based on the analysis of global energy-economy-environment scenarios described for the 21st century. We use one baseline scenario and variants thereof to estimate cumulative costs of carbon mitigation as a function of cumulative carbon emission reductions. For our baseline for estimating carbon mitigation cost curves, we use the so-called IIASA F scenario. The F scenario is a high-growth, high-emissions scenario designed specifically to be used as a reference against which to evaluate alternatives. Carbon emissions and energy systems costs in the F scenario are then compared with (reduced) emissions and (higher) costs (including macroeconomic adjustment costs) of alternative scenarios taken from the IIASA scenario database. As a kind of sensitivity analysis of our approach, we also present the results of a scenario involving assumptions on particularly rapid technological progress. [ABSTRACT FROM AUTHOR]

Editorial. Discusses the potential benefits of storing carbon in agricultural soils to offset global warming. Estimates of the Intergovernmental Panel on Climate Change on carbon sequestration; Provisions of the Kyoto Protocol about the use of carbon sequestration for greenhouse gas mitigation.

Presents a study which analyzed energy and forestry carbon mitigation scenarios in Mexico between the year 1994 and 2010. Overview of the measures and policies implemented in Mexico that address climate change concerns; Methodology; Results and discussion; Conclusions.