In this study a scenario model is used to examine if foreseen technological developments are capable of reducing CO sub(2) emissions in 2050 to a level consistent with United Nations Framework ...Convention on Climate Change (UNFCCC) agreements, which aim at maximizing the temperature rise to 2 degree C compared to pre-industrial levels. The model is based on a detailed global environmentally extended supply-use table (EE SUT) for the year 2000, called EXIOBASE. This global EE SUT allows calculating how the final demand in each region drives activities in production sectors, and hence related CO sub(2) emissions, in each region. Using this SUT framework, three scenarios have been constructed for the year 2050. The first is a business-as-usual scenario (BAU), which takes into account population, economic growth, and efficiency improvements. The second is a techno-scenario (TS), adding feasible and probable climate mitigation technologies to the BAU scenario. The third is the towards-2-degrees scenario (2DS), with a demand shift or growth reduction scenario added to the TS to create a 2 degree C scenario. The emission results of the three scenarios are roughly in line with outcomes of typical scenarios from integrated assessment models. Our approach indicates that the 2 degree C target seems difficult to reach with advanced CO sub(2) emission reduction technologies alone. Policy relevance The overall outlook in this scenario study is not optimistic. We show that CO sub(2) emissions from steel and cement production and air and sea transport will become dominant in 2050. They are difficult to reduce further. Using biofuels in air and sea transport will probably be problematic due to the fact that agricultural production largely will be needed to feed a rising global population and biofuel use for electricity production grows substantially in 2050. It seems that a more pervasive pressure towards emission reduction is required, also influencing the basic fabric of society in terms of types and volumes of energy use, materials use, and transport. Reducing envisaged growth levels, hence reducing global gross domestic product (GDP) per capita, might be one final contribution needed for moving to the 2 degree C target, but is not on political agendas now.
The Paris climate goal requires unprecedented emission reduction, while CO
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concentrations are now rising faster than ever. Internally inconsistent instrumentation has developed on the go, not fit ...for deep reduction. Mainly national technology-specific instruments, for example, have made the EU pure cap-and-trade system superfluous and have fragmented electricity markets. Systematic instrumentation design requires an adequate categorization of instruments, newly developed here for that purpose. This instrument ordering links to generality and bindingness. Starting points for any instrumentation design are sparseness, completeness, and non-overlap. Details in instrumentations may further depend on specific circumstances in different countries and regions.
Planning & Control starts with technology-specific instrumentation, with subsidies and standards to reduce fossil emissions in electricity production; effective Fleet Standards for transport; dynamic standards and permits regarding industry emissions; and standards and technology subsidies squeezing out fossils use in buildings and appliances. Subsidies create learning curves. Consistency and effectiveness tend to require centralization.
Institutionalism uses two core institutional instruments. A comprehensive upstream emission tax with proceeds to the country or state level creates incentives. An open-to-all, real-time priced electricity market enables also small-scale renewables and secondary producers on the grid. Infrastructure is provided publicly. A level playing field results for mostly decentral climate action, both public and private.
Policy relevance
Technical instrument choices may seem neutral but cannot be so: policy is about choices. Two governance strategies are now mutually competing and counteracting. Planning & Control links to welfare theory and optimization, with broad integration of several policy goals, measurable targets, and deep public-private cooperation. Institutionalism has a background in history, economics, sociology, and political science, with institutions driving long-term development. Incentives and option creation are central, indicating results only roughly. There is strict public-private delimitation. These different views on governance lead to mutually exclusive sets of instruments. Explicit instrumentation strategies are required for consistency, effectiveness, and legitimacy. Internationally, Planning & Control requires binding country caps for (almost) all countries, UN-type. Institutionalism requires a limited agreement on a high rising emission tax, open for all countries to join a starting group, WTO-type. Choices are ultimately based on governance preferences.
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 CO sub(2) 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.
Long-term scenarios generally project a steep increase in global travel demand, leading to an rapid rise in CO sub(2) emissions. Major driving forces are the increasing car use in developing ...countries and the global growth in air travel. Meeting the 2 degree C climate target, however, requires a deep cut in CO sub(2) emissions. In this paper, we explore how extensive emission reductions may be achieved, using a newly developed travel model. This bottom-up model covers 26 world regions, 7 travel modes and different vehicle types. In the experiments, we applied a carbon tax and looked into the model's responses in terms of overall travel demand, modal split shifts, and changes in technology and fuel choice. We introduce two main scenarios in which biofuels are assumed to be carbon neutral (not subject to taxation, scenario A) or to lead to some greenhouse gas emissions (and therefore subject to taxation, scenario B). This leads to very different outcomes. Scenario A achieves emission reductions mostly through changes in fuel use. In Scenario B efficiency improvement and model split changes also play a major role. In both scenarios total travel volume is affected only marginally.
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 CO ₂ 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 relevance The 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.
While most long-term mitigation scenario studies build on a broad portfolio of mitigation technologies, there is quite some uncertainty about the availability and reduction potential of these ...technologies. This study explores the impacts of technology limitations on greenhouse gas emission reductions using the integrated model IMAGE. It shows that the required short-term emission reductions to achieve long-term radiative forcing targets strongly depend on assumptions on the availability and potential of mitigation technologies. Limited availability of mitigation technologies which are relatively important in the long run implies that lower short-term emission levels are required. For instance, limited bio-energy availability reduces the optimal 2020 emission level by more than 4 GtCO₂eq in order to compensate the reduced availability of negative emissions from bioenergy and carbon capture and storage (BECCS) in the long run. On the other hand, reduced mitigation potential of options that are used in 2020 can also lead to a higher optimal level for 2020 emissions. The results also show the critical role of BECCS for achieving low radiative forcing targets in IMAGE. Without these technologies achieving these targets become much more expensive or even infeasible.
Most modelling studies that explore emission mitigation scenarios only look into least-cost emission pathways, induced by a carbon tax. This means that European policies targeting specific – ...sometimes relatively costly – technologies, such as electric cars and advanced insulation measures, are usually not evaluated as part of cost-optimal scenarios. This study explores an emission mitigation scenario for Europe up to 2050, taking as a starting point specific emission reduction options instead of a carbon tax. The purpose is to identify the potential of each of these policies and identify trade-offs between sectoral policies in achieving emission reduction targets. The reduction options evaluated in this paper together lead to a reduction of 65% of 1990 CO2-equivalent emissions by 2050. More bottom-up modelling exercises, like the one presented here, provide a promising starting point to evaluate policy options that are currently considered by policy makers.
► We model the effects of 15 climate change mitigation measures in Europe. ► We assess the greenhouse gas emission reduction potential in different sectors. ► The measures could reduce greenhouse gas emissions by 60% below 1990 levels in 2050. ► The approach allows to explore arguably more relevant climate policy scenarios.
Limiting climate change to 2 degree C with a high probability requires reducing cumulative emissions to about 1600 GtCO sub(2) over the 2000-2100 period. This requires unprecedented rates of ...decarbonization even in the short-run. The availability of the option of net negative emissions, such as bio-energy with carbon capture and storage (BECCS) or reforestation/afforestation, allows to delay some of these emission reductions. In the paper, we assess the demand and potential for negative emissions in particular from BECCS. Both stylized calculations and model runs show that without the possibility of negative emissions, pathways meeting the 2 degree C target with high probability need almost immediate emission reductions or simply become infeasible. The potential for negative emissions is uncertain. We show that negative emissions from BECCS are probably limited to around 0 to 10 GtCO sub(2)/year in 2050 and 0 to 20 GtCO sub(2)/year in 2100. Estimates on the potential of afforestation options are in the order of 0-4 GtCO sub(2)/year. Given the importance and the uncertainty concerning BECCS, we stress the importance of near-term assessments of its availability as today's decisions has important consequences for climate change mitigation in the long run.
This paper shows the importance of including region-specific circumstances in long-term climate change mitigation strategies, by example of a modeling exercise of the transport sector. Important ...emission reduction options in the transport sector include biofuels, electric vehicles and efficiency standards. The most effective combination of these options depends, among others, on the availability of biofuels, the effectiveness of efficiency standards, and the (expected) emission intensity of the power sector—all of which differ between regions. Differences in climate policies between regions influence these factors. For instance, fuel efficiency standards slowdown the long-term transition in regions where plugin hybrid electric cars compete with gasoline cars (such as the USA or Europe) by decreasing the costs for driving gasoline costs and therefore in fact increase long-term emissions. Another example is that promoting electric vehicles is less effective in regions which are expected to rely heavily on fossil fuels for power generation, such as South Africa, China and India. Based on these findings from the TIMER energy model, we introduce an indicative region-specific framework for assessing mitigation strategies for the transport sector up to 2050, for different ambition levels of climate policy.
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