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1.
To assess the potential impacts of the US withdrawal from the Paris Agreement, this study applied GCAM-TU (an updated version of the Global Change Assessment Model) to simulate global and regional emission pathways of energy-related CO 2, which show that US emissions in 2100 would reduce to ?2.4?Gt, ?0.7?Gt and ?0.2?Gt under scenarios of RCP2.6, RCP3.7 and RCP4.5, respectively. Two unfavourable policy scenarios were designed, assuming a temporary delay and a complete stop for US mitigation actions after 2015. Simulations by the Model for the Assessment of Greenhouse-gas Induced Climate Change (MAGICC) indicate that the temperature increase by 2100 would rise by 0.081°C–0.161°C compared to the three original RCPs (Representative Concentration Pathways) if US emissions were kept at their 2015 levels until 2100. The probability of staying below 2°C would decrease by 6–9% even if the US resumes mitigation efforts for achieving its Nationally Determined Contribution (NDC) target after 2025. It is estimated by GCAM-TU that, without US participation, increased reduction efforts are required for the rest of the world, including developing countries, in order to achieve the 2°C goal, resulting in 18% higher global cumulative mitigation costs from 2015 to 2100. Key policy insights President Trump’s climate policies, including planned withdrawal from the Paris Agreement, cast a shadow on international climate actions, and would lower the likelihood of achieving the 2°C target. To meet the 2°C target without the US means increased reduction efforts and mitigation costs for the rest of the world, and considerable economic burdens for major developing areas. Active state-, city- and enterprise-level powers should be supported to keep the emission reduction gap from further widening even with reduced mitigation efforts from the US federal government.
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2.
The Paris Agreement is the last hope to keep global temperature rise below 2°C. The consensus agrees to holding the increase in global average temperature to well below 2°C above pre-industrial levels, and to aim for 1.5°C. Each Party’s successive nationally determined contribution (NDC) will represent a progression beyond the party’s then current NDC, and reflect its highest possible ambition. Using Ireland as a test case, we show that increased mitigation ambition is required to meet the Paris Agreement goals in contrast to current EU policy goals of an 80–95% reduction by 2050. For the 1.5°C consistent carbon budgets, the technically feasible scenarios' abatement costs rise to greater than €8,100/tCO 2 by 2050. The greatest economic impact is in the short term. Annual GDP growth rates in the period to 2020 reduce from 4% to 2.2% in the 1.5°C scenario. While aiming for net zero emissions beyond 2050, investment decisions in the next 5–10 years are critical to prevent carbon lock-in. Key policy insights Economic growth can be maintained in Ireland while rapidly decarbonizing the energy system. The social cost of carbon needs to be included as standard in valuation of infrastructure investment planning, both by government finance departments and private investors. Technological feasibility is not the limiting factor in achieving rapid deep decarbonization. Immediate increased decarbonization ambition over the next 3–5 years is critical to achieve the Paris Agreement goals, acknowledging the current 80–95% reduction target is not consistent with temperature goals of ‘well below’ 2°C and pursuing 1.5°C. Applying carbon budgets to the energy system results in non-linear CO2 emissions reductions over time, which contrast with current EU policy targets, and the implied optimal climate policy and mitigation investment strategy.
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3.
In December 2015, China joined 190 plus nations at Paris in committing to the goal of limiting the rise in global average temperature to ‘well below’ 2°C. Carbon budget analysis indicates that goal will require not only that the European Union and US reduce their emissions by greater than 80% by 2050, but that China at least comes close to doing so as well, if any budget is to be left over for the rest of the world (RoW). Given that RoW emissions are, and will come from, low-income and emerging nations, China’s emission reduction potential is of no small consequence. In this paper, we use the Kaya identity to back out changes in the drivers of CO 2 emissions, including gross domestic product (GDP), energy intensity (E/GDP) and the carbon content of energy (C/E), the latter two calculated to be consistent with China’s long-term GDP growth rate forecasts and specified 2050 CO 2 emission reduction targets. Our results suggest that even achieving China’s highly optimistic renewable energy targets will be very far from sufficient to reduce China’s CO 2 emissions from 9.1?Gt it emitted in 2015 to much below 3?Gt by 2050. Even reducing its emissions to 5?Gt will be challenging, yet this falls far short of what is needed if the world is to meet its ‘well below’ 2°C commitment. Key policy insights Under the Paris Agreement there is great pressure on China to very substantially reduce its emissions by 2050. While China has attached great importance to renewables and nuclear energy development, even achieving the most optimistic targets would not be sufficient to reduce China’s emissions from 9.1?Gt in 2015 to much below 3?Gt by 2050. China’s emission reduction potential falls far short of what is needed if the world is to meet its Paris ‘well below’ 2°C commitment, even if the EU and US reduce their emissions to zero by 2050. Emission cuts consistent with the Paris Agreement will require that China and the world give much greater weight to advancing research and development of scalable low-, zero- and negative-carbon sources and technologies.
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4.
Globally, agriculture and related land use change contributed about 17% of the world’s anthropogenic GHG emissions in 2010 (8.4 GtCO 2e yr ?1), making GHG mitigation in the agriculture sector critical to meeting the Paris Agreement’s 2°C goal. This article proposes a range of country-level targets for mitigation of agricultural emissions by allocating a global target according to five approaches to effort-sharing for climate change mitigation: responsibility, capability, equality, responsibility-capability-need and equal cumulative per capita emissions. Allocating mitigation targets according to responsibility for total historical emissions or capability to mitigate assigned large targets for agricultural emission reductions to North America, Europe and China. Targets based on responsibility for historical agricultural emissions resulted in a relatively even distribution of targets among countries and regions. Meanwhile, targets based on equal future agricultural emissions per capita or equal per capita cumulative emissions assigned very large mitigation targets to countries with large agricultural economies, while allowing some densely populated countries to increase agricultural emissions. There is no single ‘correct’ framework for allocating a global mitigation goal. Instead, using these approaches as a set provides a transparent, scientific basis for countries to inform and help assess the significance of their commitments to reducing emissions from the agriculture sector. Key policy insights Meeting the Paris Agreement 2°C goal will require global mitigation of agricultural non-CO2 emissions of approximately 1 GtCO2e yr?1 by 2030. Allocating this 1 GtCO2e yr?1 according to various effort-sharing approaches, it is found that countries will need to mitigate agricultural business-as-usual emissions in 2030 by a median of 10%. Targets vary widely with criteria used for allocation. The targets calculated here are in line with the ambition of the few countries (primarily in Africa) that included mitigation targets for the agriculture sector in their (Intended) Nationally Determined Contributions. For agriculture to contribute to meeting the 2°C or 1.5°C targets, countries will need to be ambitious in pursuing emission reductions. Technology development and transfer will be particularly important.
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5.
In principle, many climate policymakers have accepted that large-scale carbon dioxide removal (CDR) is necessary to meet the Paris Agreement’s mitigation targets, but they have avoided proposing by whom CDR might be delivered. Given its role in international climate policy, the European Union (EU) might be expected to lead the way. But among EU climate policymakers so far there is little talk on CDR, let alone action. Here we assess how best to ‘target’ CDR to motivate EU policymakers exploring which CDR target strategy may work best to start dealing with CDR on a meaningful scale. A comprehensive CDR approach would focus on delivering the CDR volumes required from the EU by 2100, approximately at least 50 Gigatonnes (Gt) CO 2, according to global model simulations aiming to keep warming below 2°C. A limited CDR approach would focus on an intermediate target to deliver the CDR needed to reach ‘net zero emissions’ (i.e. the gross negative emissions needed to offset residual positive emissions that are too expensive or even impossible to mitigate). We argue that a comprehensive CDR approach may be too intimidating for EU policymakers. A limited CDR approach that only addresses the necessary steps to reach the (intermediate) target of ‘net zero emissions’ is arguably more achievable, since it is a better match to the existing policy paradigm and would allow for a pragmatic phase-in of CDR while avoiding outright resistance by environmental NGOs and the broader public. Key policy insights Making CDR an integral part of EU climate policy has the potential to significantly reshape the policy landscape. Burden sharing considerations would probably play a major role, with comprehensive CDR prolonging the disparity and tensions between progressives and laggards. Introducing limited CDR in the context of ‘net zero’ pathways would retain a visible primary focus on decarbonization but acknowledge the need for a significant enhancement of removals via ‘natural’ and/or ‘engineered’ sinks. A decarbonization approach that intends to lead to a low level of ‘residual emissions’ (to be tackled by a pragmatic phase-in of CDR) should be the priority of EU climate policy.
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6.
Aviation constitutes about 2.5% of all energy-related CO 2 emissions and in addition there are non-CO 2 effects. In 2016, the ICAO decided to implement a Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) and in 2017 the EU decided on faster emission reductions in its Emissions Trading System (EU ETS), which since 2012 includes the aviation sector. The effects of these policies on the expected development of air travel emissions from 2017 to 2030 have been analyzed. For the sample country Sweden, the analysis shows that when emissions reductions in other sectors are attributed to the aviation sector as a result of the EU ETS and CORSIA, carbon emissions are expected to reduce by ?0.8% per year (however if non-CO 2 emissions are included in the analysis, then emissions will increase). This is much less than what is needed to achieve the 2°C target. Our analysis of potential national aviation policy instruments shows that there are legally feasible options that could mitigate emissions in addition to the EU ETS and CORSIA. Distance-based air passenger taxes are common among EU Member States and through increased ticket prices these taxes can reduce demand for air travel and thus reduce emissions. Tax on jet fuel is an option for domestic aviation and for international aviation if bilateral agreements are concluded. A quota obligation for biofuels is a third option. Key policy insights Existing international climate policies for aviation will not deliver any major emission reductions. Policymakers who want to significantly push the aviation sector to contribute to meeting the 2°C target need to work towards putting in place tougher international policy instruments in the long term, and simultaneously implement temporary national policy instruments in the near-term. Distance-based air passenger taxes, carbon taxes on jet fuel and quota obligations for biofuels are available national policy options; if they are gradually increased, and harmonized with other countries, they can help to significantly reduce emissions.
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7.
The Paris Agreement, which entered into force in 2016, sets the ambitious climate change mitigation goal of limiting the global temperature increase to below 2°C and ideally 1.5°C. This puts a severe constraint on the remaining global GHG emissions budget. While international shipping is also a contributor to anthropogenic GHG emissions, and CO 2 in particular, it is not included in the Paris Agreement. This article discusses how a share of a global CO 2 budget over the twenty-first century could be apportioned to international shipping, and, using a range of future trade scenarios, explores the requisite cuts to the CO 2 intensity of shipping. The results demonstrate that, under a wide range of assumptions, existing short-term levers of efficiency must be urgently exploited to achieve mitigation commensurate with that required from the rest of the economy, with virtually full decarbonization of international shipping required as early as before mid-century. Key policy insights Regulatory action is key to ensuring the international shipping sector’s long-term sustainability. For the shipping industry to deliver mitigation in line with the Paris Agreement, virtually full decarbonization needs to be achieved. In the near term, immediate and rapid exploitation of available mitigation measures is of critical importance. Any delay in the transition will increase the risk of stranded assets, or diminish the chances of meeting the Paris Agreement's temperature commitments.
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8.
After the successful conclusion of the Paris Climate Conference (Conference of the Parties (COP) 21), countries are now attempting to identify implementation measures. An important consensus has been reached on the necessity of putting in place both mitigation and adaptation measures. In this context, this article builds a three-sector China and rest of the world model based on the DE-carbonization Model with Endogenous Technologies for Emission Reductions (DEMETER) and World Induced Technical Change Hybrid (WITCH) models. It assesses China’s mitigation and adaptation investment strategies by 2050 with an optimization including climate externalities. By making the 450?ppm target and China’s 2030 CO 2 emissions peak exogenous, it assesses two scenarios: (1) investment only in mitigation and (2) investment in both mitigation and adaptation. The article finds the following: First, the policy package with investment in both mitigation and adaptation can ensure lower CO 2 emissions and avoid more climate damage. Second, investment in adaptation should be massively injected by around 2040, whereas mitigation efforts should be continuous. Third, the CO 2 emissions peak in the tertiary sector should come prior to 2030 while the emissions pathway of the secondary sector could be allowed to increase slowly until 2035. POLICY RELEVANCE The necessity of engaging in both mitigation and adaptation has been widely accepted since the Paris Climate Conference (COP21), yet few studies exist in this regard concerning China. Substantial investment in adaptation needs to be introduced by 2040 while the investment on mitigation should peak by 2030. The CO2 emissions peak in the tertiary sector would be reached prior to 2030 while the peak in the secondary sector is achieved around 2035. This provides an alternative in China to the existing argument of an earlier peak in the secondary sector.
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9.
ABSTRACTThe inherently global, connected nature of aviation means that carbon leakage from aviation policy does not necessarily behave similarly to leakage from other sectors. We model carbon leakage from a range of aviation policy test cases applied to a specific country (the United Kingdom), motivated by a desire to reduce aviation CO 2 faster than achievable by currently-planned global mitigation efforts in pursuit of a year-2050 net zero CO 2 target. We find that there are two main components to leakage: one related to passenger behaviour, which tends to result in emissions reductions outside the policy area (negative leakage), and one related to airline behaviour, which tends to result in emissions increases outside the policy area (positive leakage). The overall leakage impact of a policy, and whether it is positive or negative, depends on the balance of these two components and the geographic scope used, and varies for different policy types. In our simulations, carbon pricing-type policies were associated with leakage of between +50 and ?150% depending on what is assumed about scope and the values of uncertain parameters. Mandatory biofuel use was associated with positive leakage of around 0–40%, and changes in airport landing costs to promote more fuel-efficient aircraft were associated with positive leakage of 50–150%. Key policy insights Carbon leakage in aviation policy arises from airline responses (typically positive leakage) and passenger responses (typically negative leakage). Depending on the geographical scope, policy type and values for uncertain parameters, leakage may be between around ?150 to +150%. Of the policies investigated in this study, leakage was typically most negative for carbon pricing and most positive for environmental landing charges. Absolute values of leakage are smallest where policies are considered on the basis of all arriving and departing flights.
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10.
In the recent climate change negotiations it was declared that the increase in global temperature should be kept below 2°C by 2100, relative to pre-industrial levels. China's CO 2 emissions from energy and cement processes already account for nearly 24% of global emissions, a trend that is expected to keep increasing. Thus the role of China in global GHG mitigation is crucial. A scenario analysis of China's CO 2 emissions is presented here and the feasibility of China reaching a low-carbon scenario is discussed. The results suggest that recent and continued technological progress will make it possible for China to limit its CO 2 emissions and for these emissions to peak before 2025 and therefore that the global 2°C target can be achieved. Policy relevance In signing the Copenhagen Accord, China agreed to the global 2°C target. Results from this article could be used to justify low-carbon development policies and negotiations. While many still doubt the feasibility of a low-carbon pathway to support the global 2°C target, the results suggest that such a pathway can be realistically achieved. This conclusion should increase confidence and guide the policy framework further to make possible China's low-carbon development. Related policies and measures, such as renewable energy development, energy efficiency, economic structure optimization, technology innovation, low-carbon investment, and carbon capture and storage (CCS) development, should be further enhanced. Furthermore, China can play a larger role in the international negotiations process. In the global context, the 2°C target could be reaffirmed and a global regime on an emissions mitigation protocol could be framed with countries’ emissions target up to 2050. 相似文献
11.
This article assesses Japan's carbon budgets up to 2100 in the global efforts to achieve the 2?°C target under different effort-sharing approaches based on long-term GHG mitigation scenarios published in 13 studies. The article also presents exemplary emission trajectories for Japan to stay within the calculated budget.The literature data allow for an in-depth analysis of four effort-sharing categories. For a 450?ppm CO 2e stabilization level, the remaining carbon budgets for 2014–2100 were negative for the effort-sharing category that emphasizes historical responsibility and capability. For the other three, including the reference ‘Cost-effectiveness’ category, which showed the highest budget range among all categories, the calculated remaining budgets (20th and 80th percentile ranges) would run out in 21–29 years if the current emission levels were to continue. A 550?ppm CO 2e stabilization level increases the budgets by 6–17 years-equivalent of the current emissions, depending on the effort-sharing category. Exemplary emissions trajectories staying within the calculated budgets were also analysed for ‘Equality’, ‘Staged’ and ‘Cost-effectiveness’ categories. For a 450?ppm CO 2e stabilization level, Japan's GHG emissions would need to phase out sometime between 2045 and 2080, and the emission reductions in 2030 would be at least 16–29% below 1990 levels even for the most lenient ‘Cost-effectiveness’ category, and 29–36% for the ‘Equality’ category. The start year for accelerated emissions reductions and the emissions convergence level in the long term have major impact on the emissions reduction rates that need to be achieved, particularly in the case of smaller budgets. Policy relevanceIn previous climate mitigation target formulation processes for 2020 and 2030 in Japan, neither equity principles nor long-term management of cumulative GHG emissions was at the centre of discussion. This article quantitatively assesses how much more GHGs Japan can emit by 2100 to achieve the 2?°C target in light of different effort-sharing approaches, and how Japan's GHG emissions can be managed up to 2100. The long-term implications of recent energy policy developments following the Fukushima nuclear disaster for the calculated carbon budgets are also discussed. 相似文献
12.
The Paris Agreement states that, relative to pre-industrial times, the increase in global average temperature should be kept to well below 2 °C and efforts should be made to limit the temperature increase to 1.5 °C. Emissions scenarios consistent with these targets are derived. For an eventual 2 °C warming target, this could be achieved even if CO 2 emissions remained positive. For a 1.5 °C target, CO 2 emissions could remain positive, but only if a substantial and long-lasting temperature overshoot is accepted. In both cases, a warming overshoot of 0.2 to 0.4 °C appears unavoidable. If the allowable (or unavoidable) overshoot is small, then negative emissions are almost certainly required for the 1.5 °C target, peaking at negative 1.3 GtC/year. In this scenario, temperature stabilization occurs, but cumulative emissions continue to increase, contrary to a common belief regarding the relationship between temperature and cumulative emissions. Changes to the Paris Agreement to accommodate the overshoot possibility are suggested. For sea level rise, tipping points that might lead to inevitable collapse of Antarctic ice sheets or shelves might be avoided for the 2 °C target (for major ice shelves) or for the 1.5 °C target for the West Antarctic Ice Sheet. Even with the 1.5 °C target, however, sea level will continue to rise at a substantial rate for centuries. 相似文献
13.
Studies show that the ‘well below 2°C’ target from the Paris Agreement will be hard to meet without large negative emissions from mid-century onwards, which means removing CO 2 from the atmosphere and storing the carbon dioxide in biomass, soil, suitable geological formations, deep ocean sediments, or chemically bound to certain minerals. Biomass energy combined with Carbon Capture and Storage (BECCS) is the negative emission technology (NET) given most attention in a number of integrated assessment model studies and in the latest IPCC reports. However, less attention has been given to governance aspects of NETs. This study aims to identify pragmatic ways forward for BECCS, through synthesizing the literature relevant to accounting and rewarding BECCS, and its relation to the Paris Agreement. BECCS is divided into its two elements: biomass and CCS. Calculating net negative emissions requires accounting for sustainability and resource use related to biomass energy production, processing and use, and interactions with the global carbon cycle. Accounting for the CCS element of BECCS foremost relates to the carbon dioxide capture rate and safe underground storage. Rewarding BECCS as a NET depends on the efficiency of biomass production, transport and processing for energy use, global carbon cycle feedbacks, and safe storage of carbon dioxide, which together determine net carbon dioxide removal from the atmosphere. Sustainable biomass production is essential, especially with regard to trade-offs with competing land use. Negative emissions have an added value compared to avoided emissions, which should be reflected in the price of negative emission ‘credits’, but must be discounted due to global carbon cycle feedbacks. BECCS development will depend on linkages to carbon trading mechanisms and biomass trading. Key policy insights A standardized framework for sustainable biomass should be adopted. Countries should agree on a standardized framework for accounting and rewarding BECCS and other negative emission technologies. Early government support is indispensable to enable BECCS development, scale-up and business engagement. BECCS projects should be designed to maximize learning across various applications and across other NETs. BECCS development should be aligned with modalities of the Paris Agreement and market mechanisms.
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14.
This paper employs a computable general equilibrium model (CGE) to analyse how a carbon tax and/or a national Emissions Trading System (ETS) would affect macroeconomic parameters in Turkey. The modelling work is based on three main policy options for the government by 2030, in the context of Turkey’s mitigation target under its Intended Nationally Determined Contribution (INDC), that is, reducing greenhouse gas (GHG) emissions by up to 21% from its Business as Usual (BAU) scenario in 2030: (i) improving the productivity of renewable energy by 1% per annum, a target already included in the INDC, (ii) introducing a new flat rate tax of 15% per ton of CO 2 (of a reference carbon price in world markets) imposed on emissions originating from carbon-intensive sectors, and (iii) introducing a new ETS with caps on emission permits. Our base path scenario projects that GHG emissions in 2030 will be much lower than Turkey’s BAU trajectory of growth from 430 Mt CO 2-eq in 2013 to 1.175 Mt CO 2-eq by 2030, implying that the government’s commitment is largely redundant. On the other hand, if the official target is assumed to be only a simple reduction percentage in 2030 (by 21%), but based on our more realistic base path, the government’s current renewable energy plans will not be sufficient to reach it. Turkey’s official INDC is based on over-optimistic assumptions of GDP growth and a highly carbon-intensive development pathway; A carbon tax and/or an ETS would be required to reach the 21% reduction target over a realistic base path scenario for 2030; The policy options considered in this paper have some effects on major sectors’ shares in total value-added. Yet the reduction in the shares of agriculture, industry, and transportation does not go beyond 1%, while the service sector seems to benefit from most of the policy options; Overall employment would be affected positively by the renewable energy target, carbon tax, and ETS through the creation of new jobs; Unemployment rates are lower, economic growth is stronger, and households become better off to a larger extent under an ETS than carbon taxation.
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15.
Despite the ambitious temperature goal of the 2015 Paris Agreement, the pace of reducing global CO 2 emissions remains sluggish. This creates conditions in which the idea of temperature ‘overshoot and peak-shaving’ is emerging as a possible strategy to meet the Paris goal. An overshoot and peak-shaving scenario rests upon the ‘temporary’ use of speculative solar radiation management (SRM) technologies combined with large-scale carbon dioxide removal (CDR). Whilst some view optimistically the strategic interdependence between SRM and CDR, we argue that this strategy comes with a risk of escalating ‘climate debt’. We explain our position using the logic of debt and the analogy of subprime mortgage lending. In overshoot and peak-shaving scenarios, the role of CDR and SRM is to compensate for delayed mitigation, placing the world in a double debt: ‘emissions debt’ and ‘temperature debt’. Analogously, this can be understood as a combination of ‘subprime mortgage’ (i.e. large-scale CDR) and ‘home-equity-line-of-credit’ (i.e. temporary SRM). With this analogy, we draw some important lessons from the 2007–2009 US subprime mortgage crisis. The analogy signals that the efficacy of temporary SRM cannot be evaluated in isolation of the feasibility of large-scale CDR and that the failure of the overshoot promise will lead to prolonged peak-shaving, masking an ever-rising climate debt. Overshoot and peak-shaving scenarios should not be presented as a secured feasible investment, but rather as a high-risk speculation betting on insecure promises. Obscuring the riskiness of such scenarios is a precipitous step towards escalating a climate debt crisis. Key policy insights The slow progress of mitigation increases the attraction of an ‘overshoot and peak-shaving’ scenario which combines temporary SRM with large-scale CDR Following the logic of debt, the role of CDR and SRM in this scenario is to compensate for delayed mitigation, creating a double debt of CO2 emissions and global temperature Using the analogy of subprime lending, this strategy can be seen as offering a combination of subprime mortgage and open-ended ‘line-of-credit’ Because the ‘success’ of peak-shaving by temporary SRM hinges critically on the overshoot promise of large-scale CDR, SRM and CDR should not be discussed separately
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16.
A cumulative emissions approach is increasingly used to inform mitigation policy. However, there are different interpretations of what ‘2°C’ implies. Here it is argued that cost-optimization models, commonly used to inform policy, typically underplay the urgency of 2°C mitigation. The alignment within many scenarios of optimistic assumptions on negative emissions technologies (NETs), with implausibly early peak emission dates and incremental short-term mitigation, delivers outcomes commensurate with 2°C commitments. In contrast, considering equity and socio-technical barriers to change, suggests a more challenging short-term agenda. To understand these different interpretations, short-term CO 2 trends of the largest CO 2 emitters, are assessed in relation to a constrained CO 2 budget, coupled with a ‘what if’ assumption that negative emissions technologies fail at scale. The outcomes raise profound questions around high-level framings of mitigation policy. The article concludes that applying even weak equity criteria, challenges the feasibility of maintaining a 50% chance of avoiding 2°C without urgent mitigation efforts in the short-term. This highlights a need for greater engagement with: (1) the equity dimension of the Paris Agreement, (2) the sensitivity of constrained carbon budgets to short-term trends and (3) the climate risks for society posed by an almost ubiquitous inclusion of NETs within 2°C scenarios. POLICY RELEVANCE Since the Paris meeting, there is increased awareness that most policy ‘solutions’ commensurate with 2°C include widespread deployment of negative emissions technologies (NETs). Yet much less is understood about that option’s feasibility, compared with near-term efforts to curb energy demand. Moreover, the many different ways in which key information is synthesized for policy makers, clouds the ability of policy makers to make informed decisions. This article presents an alternative approach to consider what the Paris Agreement implies, if NETs are unable to deliver more carbon sinks than sources. It illustrates the scale of the climate challenge for policy makers, particularly if the Agreement’s aim to address ‘equity’ is accounted for. Here it is argued that much more attention needs to be paid to what CO2 reductions can be achieved in the short-term, rather than taking a risk that could render the Paris Agreement’s policy goals unachievable. 相似文献
17.
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 2, we employ a climate model to calculate the long-term temperature response of CO 2 emissions. We assume that half of the stored CO 2 is permanently trapped by fast mechanisms. If 40?% of global CO 2 emissions are stored in the second half of this century, the temperature effect of escaped CO 2 is too small to compromise a 2.5 °C target. If 80?% of CO 2 is captured, escaped CO 2 must peak 300?years or later for consistency with this climate target. Due to much more CO 2 stored for the 3 than the 2.5 °C target, quality of storage becomes more important. Thus for the 3 °C target escaped CO 2 must peak 400?years or later in the 40?% scenario, and 3000?years or later in the 80?% scenario. Consequently CO 2 escaped from geological storage can compromise the less stringent 3 °C target in the long-run if most of global CO 2 emissions have been stored. If less CO 2 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. 相似文献
18.
Previous attempts to estimate the supply of greenhouse gas emission reductions from reduced emissions from deforestation (RED) have generally failed to incorporate policy developments, country-specific abilities and political willingness to supply offsets for developed countries’ emissions. To address this, we estimate policy-appropriate projections of creditable emission reductions from RED. Two global forest carbon models are used to examine major assumptions affecting the generation of credits. The results show that the estimated feasible supply of RED credits is significantly below the biophysical mitigation potential from deforestation. A literature review identified an annual RED emission reduction potential between 1.6 and 4.3 Gt CO 2e. Feasible RED supply estimates applying the OSIRIS model were 1.74 Gt CO 2e annually between 2011 and 2020, with a cumulative supply of 17.4 Gt CO 2e under an ‘own-efforts’ scenario. Estimates from the Forest Carbon Index were very low at $5/t CO 2e with 8 million tonne CO 2e annually, rising to 1.8 Gt CO 2e at $20/t CO 2e. Cumulative abatement between 2011 and 2020 was 9 billion Gt CO 2e ($20/t CO 2e). These volumes were lower, sometimes dramatically, at prices of $5/t CO 2e suggesting a non-linear supply of credits in relation to price at a low payment level. For policy makers, the results suggest that inclusion of RED in a climate framework increases abatement potential, although significant constraints are imposed by political and technical issues. 相似文献
19.
Drastic reductions of greenhouse-gas (GHG) emissions are required to meet the goal of the 2015 Paris climate accord to limit global warming to 1.5–2.0 °C over pre-industrial levels. We introduce the material stock-flow framework as a novel way to develop scenarios for future GHG emissions using methods from social metabolism research. The basic assumption behind our exploratory scenario approach is that nearly all final energy is required to either expand and maintain stocks of buildings, infrastructures and machinery or to provide services by using them. Distinguishing three country groups, we develop GDP- and population-driven scenarios for the development of these material stocks and the corresponding energy requirements based on historically calibrated model parameters. We analyze the results assuming different future pathways of CO 2 emissions per unit of primary energy. The resulting cumulative carbon emissions from 2018 to 2050 range from 361 Gt C in the lower GDP-driven to 568 GtC in the higher population-driven scenario. The findings from the population-driven scenarios point towards the huge implications of a hypothetical convergence of per-capita levels of material stocks assuming current trajectories of technological improvements. Results indicate that providing essential services with a considerably lower level of material stocks could contribute to large reductions in global resource demand and GHG emissions. A comparison of different stock levels in 2050 demonstrates that complying with ambitious climate targets requires much faster declines of CO 2 emissions per unit of primary energy if growth of material stocks is not limited. 相似文献
20.
A change in economic structure influences the total energy consumption as well as CO 2 emissions of a country, given the inherent difference in levels of energy intensity and energy fuel mix of different economic sectors. Its significance has been recognized in recent literature on China’s emission mitigation which could arguably raise China’s mitigation potential and thus the possibility of keeping the 2-degree trajectory on track. This article utilizes the past trend of economic structural change of five East Asian developed economies to project the energy consumption and CO 2 emissions of China in the coming decades. A special delineation of the economic sector is made, putting private consumption together with the three typical economic production sectors, to resolve the mismatch between the statistical data of energy consumption and economic production, in that residential energy consumption is typically merged into the tertiary sector, although it does not directly correspond to gross domestic product (GDP) output. Results suggest that the level of CO 2 emissions would be lower if China followed a development pathway emphasizing the development of the tertiary sector and continuously shrinking her secondary sector, making it possible for China to contribute more to global carbon mitigation. The impact from the rise of private consumption would be relatively insignificant compared to deindustrialization. In addition to continuous improvement in technology, economic structural change, which reduces carbon emission intensity, would be essential for China to be able to achieve the carbon emission level pledged in the Paris Agreement. Key policy insights For China, significant economic structural reform, particularly deindustrialization, is necessary to achieve the goal of ‘peak emission by 2030’. Any additional contribution from China to the global effort to maintain a 2-degree trajectory would be limited – from a ‘fair-contribution’ perspective based on share of population or GDP – because the implied mitigation targets would be almost impossible to achieve. If developing countries follow the pathway of developed economies, particularly in developing energy-intensive industries, energy consumption and CO2 emissions would significantly increase, reducing the possibility of keeping global temperature rise within the 2-degree Celsius benchmark.
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