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This paper analyses how fiscal stimulus spending in response to the COVID-19 pandemic supports the low-carbon transition. We developed a new framework to categorize rescue and recovery spending measures according to their level of greenness and their type of expected impact on greenhouse gas emissions. This framework allows to better capture how measures’ emission impacts may unfold over time and to identify the share of fiscal spending missing robust conditions or incentives to be considered low-carbon. We assess nearly 2,500 measures announced by 26 emitters as of May 2021, representing around 65% of global GHG emissions in 2018. Our findings show that the largest share (35%) of spending with potential GHG emission implications went to measures that supported the status quo in the respective countries when there were low-carbon alternatives. Our assessment reveals the different magnitudes to which the emitters have missed the opportunity for a green recovery. While low-carbon spending is also significative in size (22%) across countries, almost two-thirds of it can be considered enabling or catalytic in nature and will rather unfold its impact over time. This fiscal spending will trigger transformational change over time but will not necessarily lead to direct emission reduction impacts before 2030.

Equity is one of the key principles underpinning the global climate regime and is all the more essential given the heterogenous, self-differentiated nature of the Paris Agreement. The scientific community has proposed several effort-sharing schemes to operationalise equity – reflecting not only the multi-faceted nature of the problem but also a long history of disagreement that continues to date. We outline a synthesis framework that draws on existing estimates in the literature to develop a “fair share range” for each country within which we identify a common position, which, when applied to the ranges of all countries, results in the collective achievement of the desired temperature goal. A series of methodological choices regarding the treatment of the underlying literature and translation into a temperature equivalence are tested. We demonstrate the consistency of this framework (across different methodological choices) with the principle of “Common but Differentiated Responsibilities” – members of the OECD have the most stringent allocations, while only a few African and Asian countries (including India) have emission allocations that are above their 2010 emission levels. A few OECD members, including the European Union and Great Britain, have emission allocations in 2030 that are either close to, or less than zero. Consistency with their fair share of mitigation will require them to provide appropriate levels of international finance and support to facilitate emission reductions in developing countries. These conclusions are robust to various methodological choices.

The wave of national net zero CO2 and greenhouse gas emission targets could, if fully implemented, reduce best estimates of projected global average temperature increase to 2.1–2.4°C by 2100 and could bring achievement of the Paris Agreement within reach. 127 countries are discussing, have announced or have adopted net zero targets, which together cover 63% of global emissions. Together, these net zero targets could significantly lower projected global warming compared to currently implemented policies (2.9 to 3.2°C) or to the pledges submitted to the Paris Agreement (2.6 to 2.9°C).

The 2030 Agenda with its Sustainable Development Goals (SDGs) and the Paris Agreement on climate change were adopted in 2015. Although independently defined, the two agreements are strongly interlinked. We developed a framework that scores the impacts of climate-change actions on all SDG targets based on directionality (i.e., trade-offs or co-benefits) and likelihood of occurrence (i.e., ubiquitous or context-dependent), and categorizes them by dependence on four key context dimensions—geographical, governance, time horizon and limited natural resources. Through an extensive literature review, we found that climate-change mitigation measures directly affect most SDGs and their targets, mostly through co-benefits. Improving energy efficiency, reducing energy-services demand and switching to renewables provide the most co-benefits. In contrast, carbon capture and storage and nuclear energy likely lead to multiple trade-offs. We show how understanding the relevant context dimensions facilitates policy design and policy mixes that enhance co-benefits and minimize trade-offs. Finally, by assessing the prevalence of climate-change mitigation measures in G20 countries, we found that measures with more co-benefits are more frequently adopted. Our study advances the knowledge of climate–SDG interactions, contributing to climate and sustainable development governance research, and facilitating policy design for a joint implementation of the Paris Agreement and the 2030 Agenda.

This article tests fairness justifications offered in 168 nationally determined contributions (NDCs) to the 2015 Paris Agreement against the touchstone of principles of international environmental law. It finds that while many NDCs refer to elements and indicators that are backed by principles of international law in determining fair shares (sustainable development, special circumstances, common but differentiated responsibilities and equity), some NDCs justify their contributions on the basis of indicators not backed by such principles (indicators including small share of global emissions (for states that are not LDCs and SIDSs), least cost pathways, and emissions per GDP). These insights are used to select a sub-set of approaches to the quantification of national fair share emissions targets among approaches previously surveyed in the literature. This leads to the exclusion of approaches based on cost and grandfathering. Next, the principles of harm prevention and precaution, and the normative pillars of the climate change regime, including its objective, ‘progression’, and ‘highest possible ambition,’ and the norms relating to human rights, are engaged to argue for further narrowing the range of national fair shares such that the sum of individual contributions is collectively compatible with the Paris Agreement’s long-term temperature goal. This leads to the finding that developed states have a Paris temperature goal compatible emission level in 2030 that is net-negative. Of the G20 states, only India and Indonesia can temporarily increase their emissions relative to 2010, only India relative to today. Around half the G20 states have increased emissions over the 2010s, and those decreasing emissions have done so too slowly. Key policy insightsStates’ fairness justifications for their contributions to the Paris Agreement should be scrutinized for compatibility with widely-accepted principles of international environmental law as well as the normative pillars of the climate change regime.Fair share ranges consistent with international environmental law principles offer a benchmark for existing and new nationally determined contributions under the Paris Agreement, for peer-to-peer comparisons, and to feed into the global stocktakes.Such fair share ranges can inform climate litigation in which the adequacy of national contributions, and thus a state’s fair share, is at issue. States’ fairness justifications for their contributions to the Paris Agreement should be scrutinized for compatibility with widely-accepted principles of international environmental law as well as the normative pillars of the climate change regime. Fair share ranges consistent with international environmental law principles offer a benchmark for existing and new nationally determined contributions under the Paris Agreement, for peer-to-peer comparisons, and to feed into the global stocktakes. Such fair share ranges can inform climate litigation in which the adequacy of national contributions, and thus a state’s fair share, is at issue.

Sustainable development requires that the climate system be stabilised between 1.5°C and 2°C of average global warming. This necessitates a drastic reduction in global greenhouse gas emissions. Developing countries and emerging economies are increasingly the focus here. These nations already account for two-thirds of global emissions. Failure to achieve the goals of the Paris Agreement would ultimately undermine the achievement of just and sustainable global development that leaves no one behind. A development-oriented strategy that achieves the necessary reduction in emissions requires both climate change mitigation and development cooperation across policy fields. Tackling the now unavoidable impacts of climate change must also include matters related to land use, marine conservation and global trade. The Paris Agreement and the 2030 Agenda for Sustainable Development provide the necessary objectives and normative foundation for political action. Consistently implementing the objectives of both agendas is the key challenge for international policymakers, global corporations and for communities. In this context, it is necessary to keep all countries and population groups in view, aligning with the requirement of leaving no one behind. In addition to overarching approaches, individual action areas at the interface between climate policy and sustainable development are highly relevant. The most notable of these action areas are global energy production, the political design of urbanisation, sustainable agriculture, forest and ecosystem conservation, and the management of global freshwater resources. There are already many vantage points for international climate cooperation with developing and emerging countries. Their central role in achieving the goals of the Paris Agreement can therefore be strengthened in a sustainable manner. Provided the political will is there on the part of the partner countries and the respective national frameworks are created, the above mentioned action areas offer numerous options for intervention. This could effectively leverage the potential and experience of agents of international cooperation. The recommendations of the authors serve as examples and are spelled out in detail in the presented study.

National net zero emission targets could, if fully implemented, reduce best estimates of projected global average temperature increase to 2.0–2.4 °C by 2100, bringing the Paris Agreement temperature goal within reach. A total of 131 countries are discussing, have announced or have adopted net zero targets, covering 72% of global emissions. These targets could substantially lower projected warming as compared to currently implemented policies (2.9–3.2 °C) or pledges submitted to the Paris Agreement (2.4–2.9 °C). Current pledges for emissions cuts are insufficient to meet the Paris Agreement temperature goal. The wave of net zero targets being discussed and adopted could make the Paris goal possible if further countries follow suit.

Non-state and subnational climate actors have become central to global climate change governance. Quantitatively assessing climate mitigation undertaken by these entities is critical to understand the credibility of this trend. In this Perspective, we make recommendations regarding five main areas of research and methodological development related to evaluating non-state and subnational climate actions: defining clear boundaries and terminology; use of common methodologies to aggregate and assess non-state and subnational contributions; systematically dealing with issues of overlap; estimating the likelihood of implementation; and addressing data gaps.

Due to errors made during the production process, the printed version of the article contained one duplicate reference, which led to an inconsistent numbering in the reference list, and one incorrect citation in Table 3. The online version of the article has been updated with the corrections. The authors would like to apologize for any inconvenience caused.

Nearly all the world’s governments have prepared and submitted their Nationally Determined Contributions (NDCs), setting out their climate pledges under the 2015 Paris Agreement. These NDCs are to be regularly updated, and many countries are expected to submit a new NDC in 2020. While several studies have assessed the content and potential impacts of the NDCs, this article focusses on the preparatory process and asks the question: under what conditions can countries be expected to develop NDCs that are sufficiently ambitious to contribute to fulfilling the Paris Agreement goals? For some countries, in particular developing nations and emerging economies, the process of preparing and implementing NDCs presents challenges in terms of political support; financial, human and technical resources; and analytical capabilities. With a view to improving future NDCs, this article provides insights from the first round of NDCs. Using results from four surveys carried out in 2015, 2017 and 2018 targeting government representatives and other stakeholders from primarily developing countries and emerging economies, the article finds that the NDC preparation process contributed positively to national climate policy processes. For example, it raised political awareness and preparedness for preparing and implementing climate policies across various ministries and agencies. It also prompted institutional innovation and more coordination between various policy areas. However, more can be done to enhance analytical capacity in order for countries to make commitments based on robust analysis and data. Key policy insights In many countries, the preparation of the NDCs positively contributed to national climate policy processes by raising awareness and catalysing institutional change. The NDC process improved political buy-in across government and non-government stakeholders thereby laying the foundation for future higher NDC and climate policy ambition. A better understanding of broader impacts and the involvement of affected stakeholders in a targeted way could be conducive to reaching the goals defined in the Paris Agreement and support realistic, yet ambitious target setting. Conversely, process-related problems may lead to implementation problems. More analytical, financial and technical resources are needed to implement the first round of NDCs and support countries in preparing future NDC cycles.

The past decade of political failure on climate change has cost us all dear. It has shrunk the time left for action by two-thirds. In 2010, the world thought it had 30 years to halve global emissions of greenhouse gases. Today, we know that this must happen in ten years to minimize the effects of climate change. Incremental shifts that might once have been sufficient are no longer enough.

Important phenomena are emerging that increasingly call for enhanced or more coordinated climate governance, but that seriously challenge the capacities of a traditional governance system centered on nation-states, their legal subdivisions, and intergovernmental organizations. Climate change represents one such governance challenge. In this Perspective, we ask: What role are sub-national actors poised to play in terms of accelerating a transition to deep decarbonisation? What sorts of mitigation contributions can such actors make, in lieu of or even in concert with national pledges under the Paris Accord? To answer these questions, this Perspective first defines and identifies a range of sub-national actions and efforts undergoing on climate change. It then reviews studies that quantify non-state emissions potentials, mentions limitations with the analysis, and concludes with implications for both policy and governance efforts. The potential of sub-national action for climate mitigation appears to be substantial—up to about 20 GtCO2e, far greater than existing NDC contributions—although prone to potential overlaps and uncertainties.

The Paris climate agreement aims at holding global warming to well below 2 degrees Celsius and to "pursue efforts" to limit it to 1.5 degrees Celsius. To accomplish this, countries have submitted Intended Nationally Determined Contributions (INDCs) outlining their post-2020 climate action. Here we assess the effect of current INDCs on reducing aggregate greenhouse gas emissions, its implications for achieving the temperature objective of the Paris climate agreement, and potential options for overachievement. The INDCs collectively lower greenhouse gas emissions compared to where current policies stand, but still imply a median warming of 2.6-3.1 degrees Celsius by 2100. More can be achieved, because the agreement stipulates that targets for reducing greenhouse gas emissions are strengthened over time, both in ambition and scope. Substantial enhancement or over-delivery on current INDCs by additional national, sub-national and non-state actions is required to maintain a reasonable chance of meeting the target of keeping warming well below 2 degrees Celsius.

Increasing attention is being paid to the Paris Climate Agreement and the impacts of Nationally Determined Contributions (NDCs) intended to limit global warming to 1.5 °C. However, the nature and evolution of existing policy mixes that underlie NDCs remain poorly understood. This critical issue has emerged from the outcomes of the Talanoa Dialogue for Climate Ambition, where little progress was made in building a comprehensive, evidence-based foundation for effective climate policy. To a large extent, this is due to the nature of the process, and a lack of data related to policy interventions in the pre-2020 period, notably their composition, coverage, and orientation. We seek to address these shortcomings by applying a directed content analysis to a dataset of national and city-level policy interventions. The aim is to quantify the nature and evolution of policy efforts that promote the adoption of low-carbon energy technologies (LCETs) globally. Fifteen databases, containing more than 10,000 policies and measures were reviewed. Our findings highlight the rapid spread of policy portfolios and an international convergence towards economic incentives (notably subsidies). At the city level, technology and infrastructure policies dominate. However, it is unclear to what extent behavioural factors (i.e., cognitive, motivational and contextual aspects) that affect the choice and use of LCETs are taken into account in policy design. This is particularly important because studies that model the feasibility of the 1.5 °C target reveal behavioural changes and the rapid adoption of low-carbon lifestyles as critical enabling factors. In response to the outcomes from the Talanoa Dialogue, we argue that policymakers need to go beyond stringent policy mixes and rapidly re-think their traditional economic-driven policymaking approach. Far more attention needs to be given to behavioural factors when designing, evaluating and implementing LCET policies.

Under the Paris Agreement, countries committed to a variety of climate actions, including post-2020 greenhouse gas (GHG) emissions reduction targets. This study compares projected GHG emissions in the G20 economies under current climate policies to those under the GHG targets outlined in the nationally determined contributions (NDCs). It is based on an assessment of official governmental estimates and independent national and global studies. The study concludes that six G20 members (China, India, Indonesia, Japan, Russia and Turkey) are projected to meet their unconditional NDC targets with current policies. Eight members (Argentina, Australia, Canada, the European Union, Republic of Korea, South Africa and the United States) require further action to achieve their targets. Insufficient information is available for Saudi Arabia, and emission projections for Brazil and Mexico are subject to considerable uncertainty. The study also presents high-level decarbonisation indicators to better understand the current progress towards meeting the NDCs – Saudi Arabia and South Africa were found to continue increasing both emission intensity per unit GDP and emissions per capita under current policies by 2030 from 2015 levels.

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.

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 CO2e 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 CO2e 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 CO2e 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 relevance In 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.

Global climate change governance has changed substantially in the last decade, with a shift in focus from negotiating globally agreed greenhouse gas (GHG) reduction targets to nationally determined contributions, as enshrined in the 2015 Paris Agreement. This paper analyses trends in adoption of national climate legislation and strategies, GHG targets, and renewable and energy efficiency targets in almost all UNFCCC Parties, focusing on the period from 2007 to 2017. The uniqueness and added value of this paper reside in its broad sweep of countries, the more than decade-long coverage and the use of objective metrics rather than normative judgements. Key results show that national climate legislation and strategies witnessed a strong increase in the first half of the assessed decade, likely due to the political lead up to the Copenhagen Climate Conference in 2009, but have somewhat stagnated in recent years, currently covering 69% of global GHG emissions (almost 50% of countries). In comparison, the coverage of GHG targets increased considerably in the run up to adoption of the Paris Agreement and 93% of global GHG emissions are currently covered by such targets. Renewable energy targets saw a steady spread, with 79% of the global GHG emissions covered in 2017 compared to 45% in 2007, with a steep increase in developing countries. Key policy insightsThe number of countries that have national legislation and strategies in place increased strongly up to 2012, but the increase has levelled off in recent years, now covering 69% of global emissions by 2017 (49% of countries and 76% of global population).Economy-wide GHG reduction targets witnessed a strong increase in the build up to 2015 and are adopted by countries covering 93% of global GHG emissions (81% not counting USA) and 91% of global population (86% not counting USA) in 2017.Renewable energy targets saw a steady increase throughout the last decade with coverage of countries in 2017 comparable to that of GHG targets.Key shifts in national measures coincide with landmark international events – an increase in legislation and strategy in the build-up to the Copenhagen Climate Conference and an increase in targets around the Paris Agreement – emphasizing the importance of the international process to maintaining national momentum.

In the lead-up to the Paris Agreement, every country was invited to submit an intended nationally determined contribution (INDC), and indicate how it is fair. We analyse how countries have explained the equity of mitigation and adaptation in 163 INDCs, providing a bottom-up analysis of equity to complement a literature that has focused on top-down allocations. While no single indicator of equity was used by all INDCs, a menu of quantified indicators or tiered approaches could provide bounded flexibility across different national circumstances. The most common equity indicator used in mitigation INDCs is the country’s ‘small share’ of global emissions, followed by per capita emissions. The emissions of individual ‘small share’ INDCs add up to 24% of annual global emissions when using a consistent data set. Per capita emissions are used across a range of countries with low (0.5) to high (25 t CO2–eq per capita) values for that indicator. Adaptation is included in 89% of INDCs, of which more than half quantify impacts in some manner, and two-thirds use vulnerability as an equity argument. Broadly, we find that most claims to equity are either unsubstantiated or drawn from analysis by in-country experts. Only two INDCs refer to independent evidence, and none consider the consequences of their approach when applied to all countries. Given that the aggregate effect of INDCs will not be sufficient to keep global temperature increase well below 2 °C, and even less to keep temperature below a 1.5 °C rise, the INDCs have distributional implications. More rigorous information is needed to assess relative fair shares, which could be provided officially in future nationally determined contributions (NDCs). Absent improved information, it is likely that researchers and civil society will continue to assess informally what could be considered fair. A hybrid approach to equity—combining bottom-up assessment and top-down allocation—would be consistent with the hybrid architecture of the Paris Agreement, which comprises bottom-up elements such as NDCs and top-down elements such as global goals. Improved information on equity in NDCs will be an important input to the global stocktake ‘in the light of equity’.

If the Agreement’s goal - limit the global temperature increase below 2°C - is to be met, all financial flows need to shift dramatically and rapidly from current investment patterns to 2°C compatib ...

The results are presented from a survey of national legislation and strategies to mitigate climate change covering almost all United Nations member states between 2007 and 2012. This data set is distinguished from the existing literature in its breadth of coverage, its focus on national policies (rather than international pledges), and on the use of objective metrics rather than normative criteria. The focus of the data is limited to national climate legislation and strategies and does not cover subnational or sectoral measures. Climate legislation and strategies are important because they can: enhance incentives for climate mitigation; provide mechanisms for mainstreaming; and provide a focal point for actors. Three broad findings emerge. First, there has been a substantial increase in climate legislation and strategies between 2007 and 2012: 67% of global GHG emissions are now under national climate legislation or strategy compared to 45% in 2007. Second, there are substantial regional effects to the patterns, with most increases in non-Annex I countries, particularly in Asia and Latin America. Third, many more countries have adopted climate strategies than have adopted climate legislation between 2007 and 2012. The article concludes with recommendations for future research.Policy relevance The increase in climate legislation and strategy is significant. This spread suggests that, at the national level, there is some movement in reshaping climate governance despite the relatively slow pace of global negotiations, although the exact implications of this spread require further research on stringency of actions and their implementation. Asia and Latin America represent the biggest improvements, while OECD countries, which start from a high base, remain relatively stagnant. Implications of regional patterns are further refined by an analysis by emissions, which shows that some areas of low levels of legislation and strategy are also areas of relatively low emissions. A broad trend toward an emphasis on strategies rather than legislation, with the significant exception of China, calls for enhanced research into the practical impact of national non-binding climate strategies versus binding legislation on countries' actual emissions over time. GoVNAMAs - Phase I

In order to achieve the Paris Agreement goals of keeping the temperature rise well below 2 °C or even 1.5 °C, all countries would need to make fair and ambitious contributions to reducing emissions. A vast majority of countries have adopted reduction targets by 2030 in their Nationally Determined Contributions (NDCs). There are many alternative ways to analyze the fairness of national mitigation contributions. This article uses a model framework based on six equity principles of effort-sharing, to allocate countries’ reduction targets under global emissions scenarios consistent with meeting the Paris climate goals. It further compares these allocations with the NDCs. The analysis shows that most countries need to adopt more ambitious reduction targets by 2030 to meet 2 °C, and even more for 1.5 °C. In the context of 2 °C, the NDCs of the United States of America and the European Union lack ambition with respect to the approaches that emphasize responsibility; China’s NDC projection falls short of satisfying any approach in 2030. In the context of 1.5 °C, only India, by implementing its most ambitious efforts by 2030, could be in line with most equity principles. For most countries, the NDCs would use most of their allowed emissions space for the entire 21 st century by 2030, posing a major challenge to transform to a pathway consistent with their fair contributions in the long-term.

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-CO2 GHGs, and land-use change and forestry CO2; or about 48 % when including all these emissions and discounting historical emissions for technological progress. Excluding non-CO2 GHGs and land-use change and forestry CO2 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.

This paper provides further detail based on the Emissions Gap Report (United Nations Environment Programme, December 2010) on expected global greenhouse gas emission levels in 2020, assuming the emission reduction proposals in the Copenhagen Accord and Cancún Agreements are met. We find large differences in individual group’s results owing to uncertainties in current and projected emission estimates and in the interpretation of the reduction proposals. But regardless of these uncertainties, the pledges for 2020 are expected to deliver emission levels above those being consistent with a 2°C limit. This emissions gap could be narrowed through implementing the more stringent, conditional pledges, minimising 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” LULUCF credits and surplus emissions units, were these used to the maximum. Laying the groundwork for faster emission reduction rates after 2020 appears to be crucial in any case., JRC.H.3-Forest Resources and Climate

We have compiled historical greenhouse gas emissions and their uncertainties on country and sector level and assessed their contribution to cumulative emissions and to global average temperature increase in the past and for a the future emission scenario. We find that uncertainty in historical contribution estimates differs between countries due to different shares of greenhouse gases and time development of emissions. Although historical emissions in the distant past are very uncertain, their influence on countries’ or sectors’ contributions to temperature increase is relatively small in most cases, because these results are dominated by recent (high) emissions. For relative contributions to cumulative emissions and temperature rise, the uncertainty introduced by unknown historical emissions is larger than the uncertainty introduced by the use of different climate models. The choice of different parameters in the calculation of relative contributions is most relevant for countries that are different from the world average in greenhouse gas mix and timing of emissions. The choice of the indicator (cumulative GWP weighted emissions or temperature increase) is very important for a few countries (altering contributions up to a factor of 2) and could be considered small for most countries (in the order of 10%). The choice of the year, from which to start accounting for emissions (e.g. 1750 or 1990), is important for many countries, up to a factor of 2.2 and on average of around 1.3. Including or excluding land-use change and forestry or non-CO2 gases changes relative contributions dramatically for a third of the countries (by a factor of 5 to a factor of 90). Industrialised countries started to increase CO2 emissions from energy use much earlier. Developing countries’ emissions from land-use change and forestry as well as of CH4 and N2O were substantial before their emissions from energy use.

The Bali Action Plan as adopted under the United Nations Framework Convention on Climate Change (UNFCCC) in 2007, states that Annex I (developed) countries should reduce their greenhouse gas emissions, based on comparable efforts. Within this context, we have explored various comparable effort approaches (for example, equal marginal abatement costs for all countries) for reducing emissions by the year 2020 for individual countries and regions. In all calculations, the total reduction for Annex I countries as a group is assumed to be 30% below 1990 levels. In the analysis, we compare the reduction targets as calculated from the different approaches with the emission reductions as pledged by these countries as part of the Copenhagen Accord, as drafted under the UNFCCC in 2009. Our analysis indicates that the different elements in these calculations may cause a diversity in outcomes and that, therefore, individual countries may favour certain elements over others. These elements include (a) the choice of the approach itself (the same approach may produce very different outcomes for countries with diverging national circumstances, such as Canada and Russia); (b) the reference year (such as 1990 or 2006 emissions, is very important for countries with an increase in emissions since 1990 (e.g. the United States, Canada) or for those that have lower emission levels (e.g. Russia, the Ukraine)); and (c) rules on land use (these are important for countries with large forest areas). It should be noted that the stringency of the individual countries’ reductions as pledged, differs substantially from the stringency of the reduction targets calculated from the effort-sharing approaches. The current pledges by both the European Union and the United States, are lower than the reductions that would be obtained in the effort-sharing approaches for a 30% overall reduction in Annex I countries.

The post-2012 climate policy framework needs a global commitment to deep greenhouse gas emission cuts. This paper analyzes reaching ambitious emission targets up to 2050, either ‐ 10 % or ‐ 50 % from 1990 levels, and how the economic burden from mitigation efforts could be equitably shared between countries. The scenarios indicate a large low-cost mitigation potential in electricity and industry, while reaching low emission levels in international transportation and agricultural emissions might prove difficult. The two effort sharing approaches, Triptych and Multistage, were compared in terms of equitability and coherence. Both approaches produced an equitable cost distribution between countries, with least developed countries having negative or low costs and more developed countries having higher costs. There is, however, no definitive solution on how the costs should be balanced equitably between countries. Triptych seems to be yet more coherent than other approaches, as it can better accommodate national circumstances. Last, challenges and possible hindrances to effective mitigation and equitable effort sharing are presented. The findings underline the significance of assumptions behind effort sharing on mitigation potentials and current emissions, the challenge of sharing the effort with uncertain future allowance prices and how inefficient markets might undermine the efficiency of a cap-and-trade system.

EU Heads of State and Government agreed in March 2007 that the EU will reduce its greenhouse gas emissions to 30% below 1990 levels by 2020 within an international post-2012 climate agreement, provided that other developed (Annex I) countries commit to comparable reductions. Within this context, this paper first explores the pros and cons of many possible conceptual approaches to assess the comparability of the mitigation efforts by Annex I countries. We selected six approaches for further analysis, which represent efforts well and are technically feasible. The implications of each of these six approaches were analysed in terms of the reductions and abatement costs that must be made by different Annex I countries to meet an aggregate reduction of 20% and 30%, respectively, below 1990 levels by 2020. The analysis indicates that significant reductions are necessary for all developed countries. This study shows that reductions by the EU of at least 30%, combined with comparable reduction efforts by other developed countries to meet the aggregate Annex I reduction target of 30% by 2020 and support of developed countries for developing countries to keep their emissions 15–30% below the baseline, are sufficient to achieve the EU climate goal of 2 °C.

Following the conclusion of the official work of the Ad Hoc Group for the Modelling and Assessment of Contributions to Climate Change (MATCH), this article considers the politically more sensitive aspect of the Brazilian proposal, namely the issue of differentiating (historic) responsibility for, and not merely (causal) contribution to climate change. Its aim is (1) to highlight the fact that, while related, the two issues (‘contribution to’ and ‘responsibility for’) are fundamentally different and should not be confused, and (2) to propose a methodology for calculating shares of responsibility as opposed to the shares in causal contribution arrived at through the MATCH results. Two conceptions of responsibility (‘strict’ or ‘limited’) are applied in order to operationalize the notion of ‘respective capabilities’ given in Article 3.1 of the UNFCCC. The key message resulting from the calculations is that causal contribution—while an important indicator of (environmental) relevance to the problem—must not b...

The IPCC Fourth Assessment Report, Working Group III, summarises in Box 13.7 the required emission reduction ranges in Annex I and non-Annex I coun- tries as a group, to achieve greenhouse gas concentration stabilisation levels between 450 and 650 ppm CO2-eq. The box summarises the results of the IPCC authors' analysis of the literature on the regional allocation of the emission reductions. The box states that Annex I countries as a group would need to reduce their emissions to below 1990 levels in 2020 by 25% to 40% for 450 ppm, 10% to 30% for 550 ppm and 0% to 25% for 650 ppm CO2-eq, even if emissions in developing countries deviate substantially from baseline for the low concentration target. In this paper, the IPCC authors of Box 13.7 provide background information and analyse whether new information, obtained after completion of the IPCC report, influences these ranges. The authors concluded that there is no argument for updating the ranges in Box 13.7. The allocation studies, which were published after the writing of the IPCC report, show reductions in line with the reduction ranges in the box. From the studies analysed, this paper specifies the "substantial deviation" or "deviation from baseline" in the box: emissions of non-Annex I countries as a group have to be below the baseline roughly between 15% to 30% for 450 ppm CO2-eq, 0% to 20% for 550 ppm CO2-eq and from 10% above to 10% below the baseline for 650 ppm CO2-eq, in 2020. These ranges apply to the whole group of non-Annex I countries and may differ substantially per country. The most important factor influencing these ranges above, for non-Annex I countries, and in the box, for Annex I countries, is new information on higher baseline emissions (e.g. that of Sheehan, Climatic Change, 2008, this issue). Other factors are the assumed global emission level in 2020 and assumptions on

The Triptych approach is a method for allocating future greenhouse gas (GHG) emission reductions among countries under a post-2012 international climate mitigation regime based on technological criteria at the sector level, and accounting for structural differences. The emission allowances are decomposed according to sectors, thereby enabling the link to real-world emission reduction strategies to be more concrete. The new Triptych approach presented here is a refinement of an earlier version in terms of an increased transparency and allowing a delayed participation for developing countries (initial participation of developing countries with incentives but no penalties through ‘no lose’ targets or sustainable development policies and measures). For this article we calculated the emission reductions for countries for two technology-oriented scenarios, which stabilize GHG concentrations at 450 and 550 ppm CO 2 -eq, respectively. The reductions are ambitious, but nonetheless compatible with existing technical reduction potentials as growth is allowed but efficiency has to be improved.

This paper provides an overview of the rules for accounting emissions of land use, land use change and forestry (LULUCF) for the first commitment period of the Kyoto Protocol. It first describes the rules in detail, it then provides an overview of the history of negotiations that led to these rules and provides resulting conclusions for future international climate negotiations. We conclude that the current rules can be better understood in the light of the negotiation history. For the future, we conclude that first an agreement on the objectives of including LULUCF in the future climate regime should be developed, e.g. to contribute significantly to the ultimate objective of the convention. Further, a solid set of data should be developed that can assess the magnitude of possible options. The rules should be scientifically sound, complete and balanced as well as unambiguous before the quantitative targets are defined. They should further be simple and inclusive to include all carbon pools, i.e. provide incentives to avoid deforestation and unsustainable logging in all countries.

The “South–North Dialogue” Proposal, developed by researchers from developing and industrialised countries, outlined equitable approaches to mitigation. These approaches were based on the criteria of responsibility, capability and potential to mitigate, and include deep cuts in industrialised (Annex I) countries and differentiated mitigation commitments for developing countries. This paper quantitatively analyses the implications of the proposal for countries’ emissions and costs. The analysis focuses on a “political willingness” scenario and four stabilisation scenarios. The analysis shows that stringent stabilisation targets imply that many developing countries would have to take on quantitative mitigation obligations by 2030, even when the Annex I countries take on ambitious mitigation commitments far beyond the Kyoto obligations. The “political willingness scenario” will probably not suffice to limit a warming of the Earth's atmosphere to below 2 °C.

This article describes a new concept for an international climate regime for differentiation of future commitments: the ‘common but differentiated convergence’ approach (CDC). Under CDC, Annex-I countries' per-capita emission allowances converge within a convergence period to a low level. Individual non-Annex-I countries' allowances converge to the same level also within the same period (‘common convergence’), but starting when their per-capita emissions are a certain percentage above global average (‘differentiated’). Until then they may voluntarily take on ‘positively binding’ targets. This approach eliminates two concerns often voiced in relation to gradually converging per-capita emissions: (i) advanced developing countries have their commitment to reduce emissions delayed and their targets are not the same as Annex-I countries with equal per-capita emissions; (ii) CDC does not provide excess emission allowances to the least developing countries. Under CDC, stabilizing greenhouse gas concentr...

This paper discusses methodological issues relevant to the calculation of historical respon- sibility of countries for climate change ('The Brazilian Proposal'). Using a simple representation of the climate system, the paper compares contributions to climate change using different indicators: current radiative forcing, current GWP-weighted emissions, radiative forcing from increased concen- trations, cumulative GWP-weighted emissions, global-average surface-air temperature increase and two new indicators: weighted concentrations (analogue to GWP-weighted emissions) and integrated temperature increase. Only the last two indicators are at the same time 'backward looking' (take into account historical emissions), 'backward discounting' (early emissions weigh less, depending on the decay in the atmosphere) and 'forward looking' (future effects of the emissions are considered) and are comparable for all gases. Cumulative GWP-weighted emissions are simple to calculate but are not 'backward discounting'. 'Radiative forcing' and 'temperature increase' are not 'forward looking'. 'Temperature increase' discounts the emissions of the last decade due to the slow response of the climate system. It therefore gives low weight to regions that have recently significantly increased emissions. Results of the five different indicators are quite similar for large groups (but possibly not for individual countries): industrialized countries contributed around 60% to today's climate change, developing countries around 40% (using the available data for fossil, industrial and forestry CO2 ,C H4 and N2O). The paper further argues including non-linearities of the climate system or using a simpli- fied linear system is a political choice. The paper also notes that results of contributions to climate change need to be interpreted with care: Countries that developed early benefited economically, but have high historical emission, and countries developing at a later period can profit from developments in other countries and are therefore likely to have a lower contribution to climate change.

International negotiations under the UN Framework Convention on Climate Change could take several different approaches to advance future mitigation commitments. Options range from trying to reach consensus on specific long-term atmospheric concentration targets (e.g. 550 ppmv) to simply ignoring this contentious issue and focusing instead on what can be done in the nearer term. This paper argues for a strategy that lies between these two extremes. Internationally agreed threshold levels for certain categories of impacts or of risks posed by climate change could be translated into acceptable levels of atmospheric concentrations. This could help to establish a range of upper limits for global emissions in the medium term that could set the ambition level for negotiations on expanded GHG mitigation commitments. The paper thus considers how physical and socio-economic indicators of climate change impacts might be used to guide the setting of such targets. In an effort to explore the feasibility and implications of low levels of stabilisation, it also quantifies an intermediate global emission target for 2020 that keeps open the option to stabilise at 450 ppmv CO2 If new efforts to reduce emissions are not forthcoming (e.g. the Kyoto Protocol or similar mitigation efforts fail), there is a significant chance that the option of 450 ppmv CO2 is out of reach as of 2020. Regardless of the preferred approach to shaping new international commitments on climate change, progress will require improved information on the avoided impacts climate change at different levels of mitigation and careful assessment of mitigation costs.

The Clean Development Mechanism was designed to allow emissions reductions and sustainable development to proceed hand-in-hand. Analysis now addresses the question of whether — 14 years after its creation — it can be reformed sufficiently to serve current needs.

In December 2015, countries are scheduled to conclude negotiations on a new international climate agreement under the UN Framework Convention on Climate Change (UNFCCC) to address how to shift the world’s economy onto a low-carbon and climate-resilient pathway in a manner that is ambitious, equitable, and transparent. An approach to this agreement is needed that can provide predictability and clarity for the future pathway for emissions reductions and support greater and more rapid action in emissions reductions. This paper reviews past practice in the UNFCCC and examines some of the most promising options to improve the e ectiveness of the UNFCCC and drive greater ambition into the future with the new international climate agreement. By creating a more predictable and dynamic architecture, nations are more likely to be in a better position to drive ambition forward on a regular basis. Predictable, as there will be a clear process forward for years to come. Dynamic, as governments will be able to increase commitments at any time. Governments, business, investors, and the public will have a clearer understanding of the role of the UNFCCC in supporting the pathway to a low-carbon, climate-resilient economy. We identified the following promising options to create such an architecture, all of which could be adopted together. Parties could: 1. further specify a global long-term goal for emissions, such as a phase-out of greenhouse gas emissions to net zero by mid-century, carbon neutrality, or a global emissions reduction goal; 2. create a predictable commitment cycle to strengthen national contributions on a regular schedule—for example, ve or ten years—and continue to do so until the collective long-term goal is met. That cycle should include a series of clear steps to ensure that the Parties have adequate and dependable information and analysis; 3. decide up front that every cycle will result in greater emissions reduction or scale up actions for each Party, aiming towards a long-term goal; 4. create anassessment and revision process for each cycle that supports the Parties in identifying additional options to reduce emissions or strengthen low carbon policies and measures and areas of support and collaboration.

This report follows the evolution of carbon pricing around the world. Last year's report mapped the main carbon pricing initiatives. This year the report presents the status of each of these developing initiatives and explores the emerging trends of carbon pricing. The focus is on the recent highlights from around the world and on key lessons that can be drawn from the growing experience. Despite the difficult ongoing international climate negotiations, there is an increased focus on climate change policy and several economies are planning, implementing or refining domestic mitigation actions. These activities take careful note of past experiences, mirroring successes and dealing with weaknesses. About 40 national and over 20 sub-national jurisdictions are putting a price on carbon. Together these carbon pricing instruments cover almost 6 gigatons of carbon dioxide equivalent (GtCO2e), or about 12 percent of the annual global GHG emissions. Cooperation remains a key feature of success The international market has been struggling for some time. However, the current spate of domestic action has been buoyed by growing cooperation among regional, national and sub-national stakeholders. Piloting and scaling up carbon pricing on an international level and increasing climate finance through market-based mechanisms is an important first step. The next challenge will be to create a product that is greater than the sum of its parts by converting fragmented initiatives into internationally integrated carbon pricing approaches.

Many of the major greenhouse gas emitting countries have planned and/or implemented domestic mitigation policies, such as carbon taxes, feed-in tariffs, or standards. This study analyses whether the most effective national climate and energy policies are sufficient to stay on track for meeting the emission reduction proposals (pledges) that countries made for 2020. The analysis shows that domestic policies of India, China and Russia are projected to lead to lower emission levels than the pledged levels. Australia's and the EU's nationally legally binding policy framework is likely to deliver their unconditional pledges, but not the conditional ones. The situation is rather unclear for Japan, South Korea, Brazil and Indonesia. We project that policies of Canada and the USA will reduce 2020 emission levels, but additional policies are probably needed to deliver their pledges in full. The analysis also shows that countries are implementing policies or targets in various areas to a varying degree: all major countries have set renewable energy targets; many have recently implemented efficiency standards for cars, and new emission trading systems are emerging.

The recent announcement by the USA to withdraw their support for the Kyoto Protocol has drawn attention to the conditions under which the Protocol will enter into force: at least 55 member states to the United Nations Framework Convention on Climate Change (UNFCCC) have to ratify the Protocol, and those industrialized countries (Annex-I parties) that ratify it have to make up for at least 55% of the carbon dioxide emissions of this group in 1990. In this article, we analyze the a priori decision making power of individual parties, or groups of these, for the entry into force of the Kyoto Protocol, utilizing a mathematical approach known as the Banzhaf index. The results of our analysis suggest that the conditions for the entry into force of the Kyoto Protocol give more influence to the USA than might have been anticipated: while the USA has more voting power than the relative share of emissions suggests, all other Annex-I parties have less. Based on a mathematical model, this analysis shows that the Banzhaf index is a more realistic indicator of voting power than the bare numbers fixed in the Kyoto Protocol. This method could be used more extensively in the future for the analysis of voting procedures, in particular within the UNFCCC.

Attribution of climate change to individual countries is a part of ongoing policy discussions, e.g., the Brazil proposal, and requires a quantifiable link between emissions and climate change. We present a constrained propagation of errors that tracks uncertainties from human activities to greenhouse gas emissions, to increasing abundances of greenhouse gases, to radiative forcing of climate, and finally to climate change, thus following the causal chain for greenhouse gases emitted by developed nations since national reporting began in 1990. Errors combine uncertainties in the forward modeling at each step with top-down constraints on the observed changes in greenhouse gases and temperatures. Global surface temperature increased by +0.11 °C in 2003 due to the developed nations' emissions of Kyoto greenhouse gases from 1990 to 2002. The uncertainty range, +0.08 °C to +0.14 °C (68% confidence), is large considering that the developed countries emissions are well known for this period and that climate system modeling uncertainties are constrained by observations., JRC.H.2-Air and Climate