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Companies can support governments in bridging the emissions gap between current policies and the Paris goals by adhering to voluntary greenhouse gas (GHG) emission reduction targets that align with or surpass those implied by domestic policies. To this end, we assessed the potential impact of EU companies that set targets through the Science Based Targets Initiative (SBTi) in 2020 relative to an EU reference policies scenario that represents the estimated impact of the ETS and ESR policy instruments applicable at that time, with the aim of achieving a 40% reduction relative to 1990 by 2030. Two scenarios were assessed that incorporate the SBTi targets under these instruments: one assuming no additional reductions in the ETS sector due to the waterbed effect, and one with flanking measures to ensure additional emissions reductions regulated by ETS are materialised. Depending on the assumption made about these flanking measures, EU companies with SBTi-approved targets are projected to achieve a 4% or 14% reduction by 2030 compared to the EU 2020 policies scenario. Our findings illustrate that companies with SBTi-approved targets in 2020 were at most in line or modestly more ambitious than the 40% reduction target. This study highlights that voluntary reductions from SBTi companies regulated by ETS display higher estimated reductions than those solely regulated by ESR. Furthermore, this analysis indicates that more policy details are crucial for assessing the potential additional reduction of voluntary targets, and additional reductions under ETS should be assumed zero if a conservative estimate is required. [ABSTRACT FROM AUTHOR]

The number and coverage of climate change mitigation policies have increased in the past twenty years, but important policy adoption gaps remain. To analyse sectoral climate policy in the G20 over time (2000–2019), we compiled a dataset of climate change mitigation-relevant policies and identified 50 key policy options that constitute a comprehensive sectoral climate policy package. Approximately half of these policy options are not widely adopted. Adoption is particularly low for policies that aim to: phase out coal and oil and mandate energy reductions in electricity and heat supply; reduce industrial process emissions and incentivise fuel switch in industry; design urban planning strategies for retrofits; and support the use of renewable energy for cooking and heating/cooling purposes in buildings. Policies to remove fossil fuel subsidies and support carbon dioxide removal also need substantial improvement. However, many policy adoption gaps exist as the coverage of at least one policy option could be improved in each sector. Policy adoption gaps leave at least one-tenth of the G20's emissions completely uncovered. Filling these gaps is fundamental to realize the full mitigation potential of existing policy options and to advance the transition towards global net zero greenhouse gas emissions. Mitigation-related policy options can be presented as a matrix by sector to shed light on what constitutes a comprehensive climate policy package; looking across sectoral climate policies helps to unpack and clarify the status of adoption. Policy adoption gaps exist in all sectors. Increasing the sectoral coverage of climate policies will help to ensure that all relevant sectoral emissions and mitigation areas are considered in national mitigation efforts. Even if an increase in policy coverage alone does not ensure emission reductions, the absence of policy coverage indicates that emissions can still be further reduced and that a portion of global emissions remain uncovered by policies. Despite the observed increase in the number and coverage of climate policies, slow progress towards reducing global emissions and meeting the collective Paris climate goals calls for more comprehensive climate change mitigation policies. Filling policy adoption gaps presents a concrete strategy to improve sectoral, national and global climate policy. [ABSTRACT FROM AUTHOR]

• Assesses if nine key non-G20 countries meet 2030 GHG targets with existing policies. • Only Colombia, Iran, Morocco and Ukraine will likely meet their targets. • Thailand and DRC within reach; Kazakhstan and Philippines will miss their targets. • Per capita emissions under existing policies increase by 8 % to over 40 %. • Need to strengthen climate action analysis outside G20 for Paris Agreement goals. This study compares greenhouse gas (GHG) emissions projections in 2030 under current policies and those under 2030 mitigation targets for nine key non-G20 countries, that collectively account for about 5 % of global total emissions today. These include the four largest non-G20 fossil CO 2 emitting Parties to the UN climate convention pre- Paris Agreement (Iran, Kazakhstan, Thailand and Ukraine) and one of the largest land-use GHG emitters in the world (Democratic Republic of the Congo). Other countries assessed include major economies in their respective regions (Chile, Colombia, Morocco and the Philippines). In addition to economy-wide GHG emissions projections, we also assessed the projected GHG emissions peak year and the progression of per capita GHG emissions up to 2030. Our GHG emissions projections are also compared with previous studies. On economy-wide GHG emissions, Colombia, Iran, Morocco, and Ukraine were projected to likely meet or significantly overachieve their unconditional 2030 targets with existing policies, while DRC and Thailand would come very close to their targets. Kazakhstan and the Philippines would need to strengthen their action to meet their targets, while Chile recently raised its 2030 target ambition. Only Colombia and Ukraine are projected to have peaked their emissions by 2030. Per capita GHG emissions excluding land-use under current policies were projected to increase in all countries from 2010 levels by 8 % to over 40 % depending on the country. While the impact of the COVID-19 crisis on 2030 emissions is highly uncertain, our assessment on the target achievement would not change for most countries when the emission reductions estimated for 2020 in the literature were assumed to remain in 2030. The findings of this study highlight the importance of enhanced and frequent progress-tracking of climate action of major emitters outside G20, as is currently done for G20 members, to ensure that the global collective progress will become aligned with the pathways toward Paris climate goals. [ABSTRACT FROM AUTHOR]

The bottom-up approach of the Nationally Determined Contributions (NDCs) in the Paris Agreement has led countries to self-determine their greenhouse gas (GHG) emission reduction targets. The planned 'ratcheting-up' process, which aims to ensure that the NDCs comply with the overall goal of limiting global average temperature increase to well below 2 °C or even 1.5 °C, will most likely include some evaluation of 'fairness' of these reduction targets. In the literature, fairness has been discussed around equity principles, for which many different effort-sharing approaches have been proposed. In this research, we analysed how country-level emission targets and carbon budgets can be derived based on such criteria. We apply novel methods directly based on the global carbon budget, and, for comparison, more commonly used methods using GHG mitigation pathways. For both, we studied the following approaches: equal cumulative per capita emissions, contraction and convergence, grandfathering, greenhouse development rights and ability to pay. As the results critically depend on parameter settings, we used the wide authorship from a range of countries included in this paper to determine default settings and sensitivity analyses. Results show that effort-sharing approaches that (i) calculate required reduction targets in carbon budgets (relative to baseline budgets) and/or (ii) take into account historical emissions when determining carbon budgets can lead to (large) negative remaining carbon budgets for developed countries. This is the case for the equal cumulative per capita approach and especially the greenhouse development rights approach. Furthermore, for developed countries, all effort-sharing approaches except grandfathering lead to more stringent budgets than cost-optimal budgets, indicating that cost-optimal approaches do not lead to outcomes that can be regarded as fair according to most effort-sharing approaches. [ABSTRACT FROM AUTHOR]

This article shows the potential impact on global GHG emissions in 2030, if all countries were to implement sectoral climate policies similar to successful examples already implemented elsewhere. This assessment was represented in the IMAGE and GLOBIOM/G4M models by replicating the impact of successful national policies at the sector level in all world regions. The first step was to select successful policies in nine policy areas. In the second step, the impact on the energy and land-use systems or GHG emissions was identified and translated into model parameters, assuming that it would be possible to translate the impacts of the policies to other countries. As a result, projected annual GHG emission levels would be about 50 GtCO2e by 2030 (2% above 2010 levels), compared to the 60 GtCO2e in the ‘current policies’ scenario. Most reductions are achieved in the electricity sector through expanding renewable energy, followed by the reduction of fluorinated gases, reducing venting and flaring in oil and gas production, and improving industry efficiency. Materializing the calculated mitigation potential might not be as straightforward given different country priorities, policy preferences and circumstances. Key policy insights Considerable emissions reductions globally would be possible, if a selection of successful policies were replicated and implemented in all countries worldwide. This would significantly reduce, but not close, the emissions gap with a 2°C pathway. From the selection of successful policies evaluated in this study, those implemented in the sector ‘electricity supply’ have the highest impact on global emissions compared to the ‘current policies’ scenario. Replicating the impact of these policies worldwide could lead to emission and energy trends in the renewable electricity, passenger transport, industry (including fluorinated gases) and buildings sector, that are close to those in a 2°C scenario. Using successful policies and translating these to policy impact per sector is a more reality-based alternative to most mitigation pathways, which need to make theoretical assumptions on policy cost-effectiveness. [ABSTRACT FROM AUTHOR]

One of the most fundamental questions surrounding the new Paris Agreement is whether countries’ proposals to reduce GHG emissions after 2020 are equally ambitious, considering differences in circumstances between countries. We review a variety of approaches to assess the ambition of the GHG emission reduction proposals by countries. The approaches are applied illustratively to the mitigation part of the post-2020 climate proposals (nationally determined contributions, or NDCs) by China, the EU, and the US. The analysis reveals several clear trends, even though the results differ per individual assessment approach. We recommend that such a comprehensive ambition assessment framework, employing a large variety of approaches, is used in the future to capture a wide spectrum of perspectives on ambition. POLICY RELEVANCE Assessing the ambition of the national climate proposals is particularly important as the Paris Agreement asks for regular reviews of national contributions, keeping in mind that countries raise their ambition over time. Such an assessment will be an important part of the regular global stocktake that will take place every five years, starting with a ‘light’ version in 2018. However, comprehensive methods to assess the proposals are lacking. This article provides such a comprehensive assessment framework. [ABSTRACT FROM AUTHOR]

As part of the Paris climate agreement, countries have submitted (Intended) Nationally Determined Contributions (NDCs), which includes greenhouse gas reduction proposals beyond 2020. In this paper, we apply the IMAGE integrated assessment model to estimate the annual abatement costs of achieving the NDC reduction targets, and the additional costs if countries would take targets in line with keeping global warming well below 2 °C and “pursue efforts” towards 1.5 °C. We have found that abatement costs are very sensitive to socio-economic assumptions: under Shared Socioeconomic Pathway 3 (SSP3) assumptions of slow economic growth, rapidly growing population, and high inequality, global abatement costs of achieving the unconditional NDCs are estimated at USD135 billion by 2030, which is more than twice the level as under the more sustainable socio-economic assumptions of SSP1. Furthermore, we project that the additional costs of full implementation of the conditional NDCs are substantial, ranging from 40 to 55 billion USD, depending on socio-economic assumptions. Of the ten major emitting economies, Brazil, Canada and the USA are projected to have the highest cots as share of GDP to implement the conditional NDCs, while the costs for Japan, China, Russia, and India are relatively low. Allowing for emission trading could decrease global costs substantially, by more than half for the unconditional NDCs and almost by half for the conditional NDCs. Finally, the required effort in terms of abatement costs of achieving 2030 emission levels consistent with 2 °C pathways would be at least three times higher than the costs of achieving the conditional NDCs – even though reductions need to be twice as much. For 1.5 °C, the costs would be 5–6 times as high. [ABSTRACT FROM AUTHOR]

Greenhouse gas emissions associated with Representative Concentration Pathway RCP2.6 could limit global warming to around or below a 2 °C increase since pre-industrial times. However this scenario implies very large and rapid reductions in both carbon dioxide (CO 2 ) and non-CO 2 emissions, and suggests a need to understand available flexibility between how different greenhouse gases might be abated. There is a growing interest in developing a greater understanding of the particular role of shorter lived non-CO 2 gases as abatement options. We address this here through a sensitivity study of different methane (CH 4 ) emissions pathways to year 2100 and beyond, by including exchanges with CO 2 emissions, and with a focus on related climate and economic advantages and disadvantages. Metrics exist that characterise gas equivalence in terms of climate change effect per tonne emitted. We analyse the implications of CO 2 and CH 4 emission exchanges under two commonly considered metrics: the 100-yr Global Warming Potential (GWP-100) and Global Temperature Potential (GTP-100). This is whilst keeping CO 2 -equivalent emissions pathways fixed, based on the standard set of emissions usually associated with RCP2.6. An idealised situation of anthropogenic CH 4 emissions being reduced to zero across a period of two decades and with the implementation of such cuts starting almost immediately gives lower warming than for standard RCP2.6 emissions during the 21st and 22nd Century. This is despite exchanging for higher CO 2 emissions. Introducing Marginal Abatement Cost (MAC) curves provides an economic assessment of alternative gas reduction strategies. Whilst simpler than utilising full Integrated Assessment Models (IAMs), MAC curves are more transparent for illustrative modelling. The GWP-100 metric places a relatively high value on climate change prevented for methane emission reduction, as compared to an equivalent mass of CO 2 reduction. This in combination with the strong non-linearity in MAC curves (moving quickly from relatively cheap removal to emissions difficult to cut at any cost) causes little change under cost minimisation from standard RCP2.6 emissions. This reflects the original development of RCP2.6 standard emissions from similar minimisation. With gas exchange under GTP-100, however, we find much less methane is abated, resulting in higher temperatures, whilst costs are slightly lower. Our results also highlight the point at which greater methane mitigation would become beneficial from both a climate and economic aspect. If by 2030 removal of all methane were to become possible at an average cost less than $1000 per tonne of CH 4 , then this would be the cheapest option, for GWP-100 metric and our CO 2 MAC curve. Critically this would increase the possibility of constraining warming to two degrees. [ABSTRACT FROM AUTHOR]

Over 40 studies that analyse future GHG emissions allowances or reduction targets for different regions based on a wide range of effort-sharing approaches and long-term concentration stabilization levels are compared. This updates previous work undertaken for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Regional reduction targets differ significantly for each effort-sharing approach. For example, in the Organisation for Economic Co-operation and Development (OECD) 1990 region, new proposals that emphasize the equity principles of responsibility, capability, and need, and those based on equal cumulative per capita emissions (carbon budgets), lead to relatively stringent emissions reduction targets. In order to reach a low concentration stabilization level of 450 ppm CO2e, the allowances under all effort sharing approaches in OECD1990 for 2030 would be approximately half of the emissions of 2010 with a large range, roughly two-thirds in the Economies in Transition (EIT), roughly at the 2010 emissions level or slightly below in Asia, slightly above the 2010 level in the Middle East and Africa and well below the 2010 level in Latin America. For 2050, allowances in OECD1990 and EIT would be a fraction of today's emissions, approximately half of 2010 emission levels in Asia, and possibly less than half of the 2010 level in Latin America. Policy relevance The concept of equity and the stringency of future national GHG reduction targets are at the heart of the current debate on the new international climate change agreement to be adopted in 2015. Policy insights gained from an analysis of over 40 studies, which have quantitatively analysed the proposed GHG reduction targets, are presented. It is found that the outcome of effort-sharing approaches is often largely determined by the way the equity principle is implemented and that the distributional impacts of such approaches can be significantly different depending on the criteria used, the stabilization level and shape of the global emissions pathway. However, the current literature only covers a small proportion of the possible allocation approaches. There should thus be an in-depth modelling comparison to ensure consistency and comparability of results and inform decision making regarding the reduction of GHG emissions. [ABSTRACT FROM PUBLISHER]

In the context of recent discussions at the UN climate negotiations we compared several ways of calculating historical greenhouse gas (GHG) emissions, and assessed the effect of these different approaches on countries’ relative contributions to cumulative global emissions. Elements not covered before are: (i) including recent historical emissions (2000–2010), (ii) discounting historical emissions to account for technological progress; (iii) deducting emissions for ‘basic needs’; (iv) including projected emissions up to 2020, based on countries’ unconditional reduction proposals for 2020. Our analysis shows that countries’ contributions vary significantly based on the choices made in the calculation: e.g. the relative contribution of developed countries as a group can be as high as 80 % when excluding recent emissions, non-CO 2 GHGs, and land-use change and forestry CO 2; or about 48 % when including all these emissions and discounting historical emissions for technological progress. Excluding non-CO 2 GHGs and land-use change and forestry CO 2 significantly changes relative historical contributions for many countries, altering countries’ relative contributions by multiplicative factors ranging from 0.15 to 1.5 compared to reference values (i.e. reference contribution calculations cover the period 1850-2010 and all GHG emissions). Excluding 2000–2010 emissions decreases the contributions of most emerging economies (factor of up to 0.8). Discounting historical emissions for technological progress reduces the relative contributions of some developed countries (factor of 0.8) and increases those of some developing countries (factor of 1.2–1.5). Deducting emissions for ‘basic needs’ results in smaller contributions for countries with low per capita emissions (factor of 0.3–0.5). Finally, including projected emissions up to 2020 further increases the relative contributions of emerging economies by a factor of 1.2, or 1.5 when discounting pre-2020 emissions for technological progress. [ABSTRACT FROM AUTHOR]

This article provides further detail on expected global GHG emission levels in 2020, based on the Emissions Gap Report (United Nations Environment Programme, December 2010), assuming the emission reduction proposals in the Copenhagen Accord and Cancun Agreements are met. Large differences are found in the results of individual groups owing to uncertainties in current and projected emission estimates and in the interpretation of the reduction proposals. Regardless of these uncertainties, the pledges for 2020 are expected to deliver emission levels above those that are consistent with a 2°C limit. This emissions gap could be narrowed through implementing the more stringent conditional pledges, minimizing the use of ‘lenient’ credits from forests and surplus emission units, avoiding double-counting of offsets and implementing measures beyond current pledges. Conversely, emission reduction gains from countries moving from their low to high ambition pledges could be more than offset by the use of ‘lenient’ land use, land-use change and forestry (LULUCF) credits and surplus emissions units, if these were used to the maximum. Laying the groundwork for faster emission reduction rates after 2020 appears to be crucial in any case. [ABSTRACT FROM PUBLISHER]

Abstract: As part of the Copenhagen Accord, Annex I Parties (industrialised countries) and non-Annex I Parties (developing countries) have submitted reduction proposals (pledges) and mitigation actions to the UNFCCC secretariat. Our calculations show that if the current reduction offers of Annex I and non-Annex I countries are fully implemented, global greenhouse gas emissions could amount to 48.6–49.7 GtCO2eq by 2020. Recent literature suggests that the emission level should be between 42 and 46 GtCO2eq by 2020 to maintain a “medium” chance (50–66%) of meeting the 2°C target. The emission gap is therefore 2.6–7.7 GtCO2eq. We have identified a combined set of options, which could result in an additional 2.8 GtCO2eq emission reduction. This would lead to an emission level just within the range needed. The options include reducing deforestation and emissions from bunker fuels, excluding emissions allowance increases from land use and forestry rules, and taking into account the national climate plans of China and India. However, there are also important risks that could widen the emissions gap, like lower reductions from countries with only a conditional pledge and the use of Kyoto and/or trading of new surplus emission allowances. [Copyright &y& Elsevier]

Abstract: As part of the Copenhagen Accord, individual countries have submitted greenhouse gas reduction proposals for the year 2020. This paper analyses the implications for emission reductions, the carbon price, and abatement costs of these submissions. The submissions of the Annex I (industrialised) countries are estimated to lead to a total reduction target of 12–18% below 1990 levels. The submissions of the seven major emerging economies are estimated to lead to an 11–14% reduction below baseline emissions, depending on international (financial) support. Global abatement costs in 2020 are estimated at about USD 60–100 billion, assuming that at least two-thirds of Annex I emission reduction targets need to be achieved domestically. The largest share of these costs are incurred by Annex I countries, although the costs as share of GDP are similar for Annex I as a group and the seven emerging economies as a group, even when assuming substantial international transfers from Annex I countries to the emerging economies to finance their abatement costs. If the restriction of achieving two-thirds of the emission reduction target domestically is abandoned, it would more than double the international carbon price and at the same time reduce global abatement costs by almost 25%. [Copyright &y& Elsevier]

Many studies have been published to evaluate the consequences of different post- 2012 emission allocation regimes on regional mitigation costs. This paper goes one step further and evaluates not only mitigation costs, but also adaptation costs and climate change damages. Three post-2012 emission allocation regimes (Contraction & Convergence, Multistage and Common but differentiated convergence) and two climate targets (2°C and 3°C above the pre-industrial level) are considered. This explorative analysis shows that including these other cost categories could lead to different perspectives on the outcomes of allocation regimes. Up to 2050, the poorest regions have negative mitigation costs under all allocation regimes considered, as they benefit from emission trading. However, these regions also suffer from the most severe climate impacts. As such, the financial flows due to emission trading from developed to developing countries created under these allocation regimes could also be interpreted as compensation of climate change damages and adaptation costs. In the longer run, the sum of climate change damages, adaptation costs and mitigation costs are the highest in the poorest regions of Sub-Saharan Africa and South Asia, for both climate targets and practically all emission allocation regimes. [ABSTRACT FROM AUTHOR]

This paper presents a set of technically feasible multi-gas emission pathways (envelopes) for stabilising greenhouse gas concentration at 450, 550 and 650ppm CO2-equivalent and their trade-offs between direct abatement costs and probabilities to meet temperature targets. There are different pathways within the envelope. Delayed response pathways initially follow the upper boundary of the emission envelope and reduce more by the end of the century. In contrast, early action pathways first follow the lower boundary and then the upper boundary. The latter require an early peak in the global emissions but keeps the option open for shifting to lower concentration targets in the future. Costs evaluations depend on the discount rate. Early action profiles have high costs early on, but learning-by-doing and smoother reduction rates over time lead to in most cases to lower costs across the century (net present value (NPV)). To achieve the 450ppm CO2-equivalent, the global emissions need to peak before 2020. The NPV of costs increase from 0.2% of cumulative gross domestic product to 1.0% as the shift is made from 650 to 450ppm (discount rate 5%). However, the chances of limiting global mean warming to 2°C above pre-industrial levels are very small for peaking and stabilisation at 650ppm (1–23%) and 550ppm (1–48%), but increase for a peaking at 510ppm with subsequent stabilisation 450ppm to 14–67%. [Copyright &y& Elsevier]

A methodology is presented here to assess the potential long-term contribution of non-CO2 greenhouse gases in mitigation scenarios. The analysis shows the future development of the mitigation potential of non-CO2 gases (as a function of changes in technology and implementation barriers) to represent a crucial parameter for the overall costs of mitigation scenarios. The recently developed marginal abatement cost curves for 2010 in the EMF-21 project are taken as the starting point. First-order estimates were made of the future maximum attainable reduction potentials and costs on the basis of available literature. The set of MAC curves developed was used in a multi-gas analysis for stabilising greenhouse gas concentrations at 550ppm CO2-equivalent. Including future development for the non-CO2 mitigation options not only increases their mitigation potential but also lowers the overall costs compared to situations where no development is assumed (3–21% lower in 2050 and 4–26% lower in 2100 in our analysis). Along with the fluorinated gases, energy-related methane emissions make up the largest share in total non-CO2 abatement potential as they represent a large emission source and have a large potential for reduction (towards 90% compared to baseline in 2100). Most methane and nitrous oxide emissions from landuse-related sources are less simple to abate, with an estimated abatement potential in 2100 of around 60% and 40%, respectively. [Copyright &y& Elsevier]

On the basis of the IPCC B2, A1b and B1 baseline scenarios, mitigation scenarios were developed that stabilize greenhouse gas concentrations at 650, 550 and 450 and--subject to specific assumptions--400 ppm CO2-eq. The analysis takes into account a large number of reduction options, such as reductions of non-CO2 gases, carbon plantations and measures in the energy system. The study shows stabilization as low as 450 ppm CO2-eq. to be technically feasible, even given relatively high baseline scenarios. To achieve these lower concentration levels, global emissions need to peak within the first two decades. The net present value of abatement costs for the B2 baseline scenario (a medium scenario) increases from 0.2% of cumulative GDP to 1.1% as the shift is made from 650 to 450 ppm. On the other hand, the probability of meeting a two-degree target increases from 0%--10% to 20%--70%. The mitigation scenarios lead to lower emissions of regional air pollutants but also to increased land use. The uncertainty in the cost estimates is at least in the order of 50%, with the most important uncertainties including land-use emissions, the potential for bio-energy and the contribution of energy efficiency. Furthermore, creating the right socio-economic and political conditions for mitigation is more important than any of the technical constraints. [ABSTRACT FROM AUTHOR]

In this paper we argue that the discussion on how to get to an equitable global climate change regime requires a long-term context. Some key dimensions of this discussion are responsibility, capability and development needs. Each of these, separately or in combination, has been used in designing schemes for differentiation of commitments to limit or reduce greenhouse gas emissions. Many implementation problems of these proposals are often side-stepped. In particular, some proposals may be incompatible with Article 2 of the United Nations Framework Convention on Climate Change (UNFCCC), i.e. they are unlikely to keep the option open of long-term stabilisation of atmospheric greenhouse gas concentrations at relatively low levels. We present some evidence that shifting the emphasis from emission reduction to sustainable development needs can contribute significantly to relieving the threat of human-induced climate change. [Copyright &y& Elsevier]