Zero carbon energy system pathways for Ireland consistent with the Paris Agreement

The Paris Agreement is the last hope to keep global temperature rise below 2°C. The consensus agrees to holding the increase in global average temperature to well below 2°C above pre-industrial levels, and to aim for 1.5°C. Each Party’s successive nationally determined contribution (NDC) will represent a progression beyond the party’s then current NDC, and reflect its highest possible ambition. Using Ireland as a test case, we show that increased mitigation ambition is required to meet the Paris Agreement goals in contrast to current EU policy goals of an 80–95% reduction by 2050. For the 1.5°C consistent carbon budgets, the technically feasible scenarios' abatement costs rise to greater than €8,100/tCO₂ by 2050. The greatest economic impact is in the short term. Annual GDP growth rates in the period to 2020 reduce from 4% to 2.2% in the 1.5°C scenario. While aiming for net zero emissions beyond 2050, investment decisions in the next 5–10 years are critical to prevent carbon lock-in.

Key policy insights

• Economic growth can be maintained in Ireland while rapidly decarbonizing the energy system.

• The social cost of carbon needs to be included as standard in valuation of infrastructure investment planning, both by government finance departments and private investors.

• Technological feasibility is not the limiting factor in achieving rapid deep decarbonization.

• Immediate increased decarbonization ambition over the next 3–5 years is critical to achieve the Paris Agreement goals, acknowledging the current 80–95% reduction target is not consistent with temperature goals of ‘well below’ 2°C and pursuing 1.5°C.

• Applying carbon budgets to the energy system results in non-linear CO₂ emissions reductions over time, which contrast with current EU policy targets, and the implied optimal climate policy and mitigation investment strategy.

     

国家自主贡献更新进展、特征及其对全球气候治理的影响

国家自主贡献(NDC)是《巴黎协定》最核心的制度,体现了全球气候治理模式从"自上而下"到"自下而上"的变迁.文中对截至2021年7月1日92个缔约方通报或更新的NDC进行了比较分析,识别出7种更新方式:提高量化减排目标数字、调整减排目标类型和覆盖范围、增加适应目标和政策、增加2050年减排愿景、主动适用NDC信息和核算...     

美国退出《巴黎协定》的原因、影响及中国的对策

综合应用定性与定量分析方法,分析美国宣布退出《巴黎协定》的原因,评估美国退出《巴黎协定》对《巴黎协定》履约前景的影响并提出中国的应对策略。美国宣布退出《巴黎协定》是全球气候治理的重大事件,将对《巴黎协定》的履约产生多重影响,包括将对《巴黎协定》的普遍性构成严重伤害,动摇以《巴黎协定》为核心的国际气候治理体制的基础;将导致《巴黎协定》履约中的领导力赤字问题显著恶化;可能引发不良示范效应,降低国际气候合作信心;将会对其他地区碳排放空间形成不可忽视的挤压,进而推高其他地区碳减排成本;美国大幅削减国际气候援助资金将削弱发展中国家减缓和适应气候变化的能力;美国延迟采取气候行动可能导致全球减排错失最佳时间窗口;美国大幅削减气候变化基础研究经费将对未来全球气候科学研究产生不利影响,进而影响《巴黎协定》履约谈判的权威性等,最后显著加大实现温控目标的难度,甚至导致目标无法实现。就全球气候治理的全局而言,全球气候治理的框架不会坍塌,但确实会受到动摇;全球气候治理的进程不会逆转,但确实会迟滞。美国宣布退出《巴黎协定》使中国面临多重挑战,其中之一是中国面临急剧上升的期望中国承担全球气候治理领导的国际压力。为此,中国对内应实现国家自主贡献的上限目标,对外应积极重建全球气候治理集体领导体制,即用C5取代G2,同时继续努力改变美国对气候变化的消极立场。     

Beyond headline mitigation numbers: we need more transparent and comparable NDCs to achieve the Paris Agreement on climate change

Nationally determined contributions (NDCs) were key to reaching the Paris Agreement and will be instrumental in implementing it. Research was quick to identify the ‘headline numbers’ of NDCs: if these climate action plans were fully implemented, global mean warming by 2100 would be reduced from approximately 3.6 to 2.7°C above pre-industrial levels (Höhne et al. Climate Pol 17:1–17, 2016; Rogelj et al. Nature 534:631–639, 2016). However, beyond these headline mitigation numbers, NDCs are more difficult to analyse and compare. UN climate negotiations have so far provided limited guidance on NDC formulation, which has resulted in varying scopes and contents of NDCs, often lacking details concerning ambitions. If NDCs are to become the long-term instrument for international cooperation, negotiation, and ratcheting up of ambitions to address climate change, then they need to become more transparent and comparable, both with respect to mitigation goals, and to issues such as adaptation, finance, and the way in which NDCs are aligned with national policies. Our analysis of INDCs and NDCs (Once a party ratifies the Paris Agreement, it is invited to turn its Intended Nationally Determined Contribution (INDC) into an NDC. We refer to results from our INDC analysis rather than our NDC analysis in this commentary unless otherwise stated.) shows that they omit important mitigation sectors, do not adequately provide details on costs and financing of implementation, and are poorly designed to meet assessment and review needs.     

Swimming upstream: addressing fossil fuel supply under the UNFCCC

Reducing fossil fuel supply is necessary to meet the Paris Agreement goal to keep warming ‘well below 2°C’, yet the Agreement is silent on the topic of fossil fuels. This article outlines reasons why it is important that Parties to the Agreement find ways to more explicitly address the phasing out of fossil fuel production under the UNFCCC. It describes how countries aiming to keep fossil fuel supply in line with Paris goals could articulate and report their actions within the current architecture of the Agreement. It also outlines specific mechanisms of the Paris Agreement through which issues related to the curtailment of fossil fuel supply can be addressed. Mapping out a transition away from fossil fuels – and facilitating this transition under the auspices of the UNFCCC process – can enhance the ambition and effectiveness of national and international climate mitigation efforts.

Key policy insights

• The international commitment to limit global average temperature increases to ‘well below 2°C’ provides a strong rationale for Parties to the Paris Agreement and the UNFCCC to pursue a phase-down in fossil fuel production, not just consumption.

• Several countries have already made commitments to address fossil fuel supply, by agreeing to phase down coal or oil exploration and production.

• Integrating these commitments into the UNFCCC process would link them to global climate goals, and ensure they form part of a broader global effort to transition away from fossil fuels.

• The Paris Agreement provides a number of new opportunities for Parties to address fossil fuel production.

     

Additionality revisited: guarding the integrity of market mechanisms under the Paris Agreement

ABSTRACT

The Paris Agreement requires mitigation contributions from all Parties. Therefore, the determination of additionality of activities under the market mechanisms of its Article 6 will need to be revisited. This paper provides recommendations on how to operationalize additionality under Article 6. We first review generic definitions of additionality and current approaches for testing of additionality before discussing under which conditions additionality testing of specific activities or policies is still necessary under the new context of the Paris Agreement, that is, in order to prevent increases of global emissions. We argue that the possibility of ‘hot air’ generation under nationally-determined contributions (NDCs) requires an independent check of the NDC’s ambition. If the NDC of the transferring country does contain ‘hot air’, or if the transferred emission reductions are not covered by the NDC, a dedicated additionality test should be required. While additionality tests of projects and programmes could continue to be done through investment analysis, for policy instruments new approaches are required. They should be differentiated according to type of policy instrument. For regulation, we suggest calculating the resulting pay-back period for technology users. If the regulation generates investments exceeding a payback period threshold, it could be deemed additional. Similarly, carbon pricing policies that generate a carbon price exceeding a threshold could qualify; for trading schemes an absence of over-allocation needs to be shown. The threshold should be differentiated according to country categories and rise over time.

Key policy insights

• Without additionality testing, market mechanisms under the Paris Agreements might lead to an international diffusion of ‘hot air’. To avoid this, an independent assessment of NDC ambition is in order. Otherwise, activities under the mechanisms need to undergo specific additionality tests.

• Additionality testing of projects and programmes should build on the experience developed under the Kyoto Protocol mechanisms.

• Bold approaches are needed for assessing additionality of policies. To avoid cumbersome assessment of all activities triggered by such policies, highly aggregated approaches are suggested, ranging from payback period thresholds for technologies mandated by regulation to minimum price levels triggered by carbon pricing policies. Over time, the stringency of threshold values should increase.

     

What future for the voluntary carbon offset market after Paris? An explorative study based on the Discursive Agency Approach

The Paris Agreement heralds a new era in international climate governance. Yet, the Agreement's implementation rulebook is still under negotiation. During this transition, from the Kyoto Protocol to the new regime under the Paris Agreement, many non-state actors are facing a high level of uncertainty. In particular, actors in the voluntary carbon market are struggling to define their new role. The business model of producing carbon credits in developing countries and selling them elsewhere is threatened. Although its financial significance and achieved emission reductions are limited, the voluntary market's role as an incubator for innovation has made it a prominent representative of non-state mitigation mechanisms. Therefore, we ask: What effects will the regime change to the Paris Agreement have on the voluntary carbon offset market (VCM) and how does it react to these effects?

This study analyses perceptions of, and reactions to, the new regulatory environment within the VCM. We apply the Discursive Agency Approach to scrutinize the institutions, discourses and influential agents involved in the VCM, and the strategic practices they apply to manage the transition towards the Paris regime. We find two dominant coping strategies: to align the voluntary offsetting mechanism with the Paris Agreement, and to re-invent its overall purpose as a tool to deliver sustainable development rather than solely emission reductions. Based on these results, we outline ‘thought spaces’ for a future VCM: (1) voluntary and non-party offsetting beyond nationally determined contributions (NDCs), (2) results-based financing for emission reductions and sustainable development, and (3) private climate action under international oversight.

Key policy insights

• The Paris Agreement threatens the VCM's business model, prompting market agents to frame and legitimize their work in new ways.

• The voluntary market's viability depends on the future accounting rules for emission reductions under Paris Agreement Article 6. Discursive struggles surround the risks of double counting and NDC ambitions.

• Based on an understanding of the past, we can draw lessons from agents’ attempts to re-legitimize their role under the new Paris Agreement; their future visions will shape the debates about this nascent regime.

     

Is India pulling its weight? India’s nationally determined contribution and future energy plans in global climate policy

Ahead of the Conference of Parties (COP) 24 where countries will first take stock of climate action post Paris, this paper assesses India’s progress on its nationally determined contribution (NDC) targets and future energy plans. We find that, although India is well on track to meet its NDC pledges, these targets were extremely modest given previous context. Furthermore, there is considerable uncertainty around India’s energy policy post 2030 and if current plans for energy futures materialise, the Paris Agreement’s 2 degrees goal will be almost certainly unachievable. India’s role in international climate politics has shifted from obstructionism to leadership particularly following the announcement of withdrawal by the United States from the Paris Agreement, but analysis reveals that India’s ‘hard’ actions on the domestic front are inconsistent with its ‘soft’ actions in the international climate policy arena. Going forward, India is likely to face increasing calls for stronger mitigation action and we suggest that this gap can be bridged by strengthening the links between India’s foreign policy ambitions, international climate commitments, and domestic energy realities.

Key policy insights

• India’s NDC pledges on carbon intensity and share of non-fossil fuel capacity are relatively modest given domestic context and offer plenty of room to increase ambition of action.

• India’s ‘soft’ leadership in global climate policy can be matched by ‘hard’ commitments by bringing NDC pledges in line with domestic policy realities.

• There is significant uncertainty around future plans for coal power in India which have the potential to exceed the remaining global carbon budget for 2 degrees.

     

National climate change mitigation legislation,strategy and targets: a global update

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 70% 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 89% 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 insights

• The 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 70% of global emissions by 2017 (48% 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 89% of global GHG emissions (76% not counting USA) and 90% 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.

     

How to operationalize accounting under Article 6 market mechanisms of the Paris Agreement

The role of market mechanisms was far from certain in the lead up to the 2015 Paris Climate Conference. The use of ‘constructive ambiguity’ led to Article 6 of the Paris Agreement, with Article 6.2 specifying a mechanism with limited international oversight, and Article 6.4 establishing a ‘Sustainable Development Mechanism’ (SDM) subject to detailed rules. Clear operationalization of these mechanisms remains a challenge, especially regarding the critical accounting issue that could not be resolved at the 2018 Katowice Climate Conference (COP24) – how to apply corresponding adjustments, especially regarding sectors not covered by targets under nationally-determined contributions (NDCs). By using fictitious examples, we explain two possible approaches to using Internationally Transferred Mitigation Outcomes (ITMOs) under Article 6.2 for achieving NDCs: a ‘target-based’ one where the acquiring Party adds the ITMO amount to the target level of its NDC; and a ‘tally-based’ one where the acquiring Party removes the ITMO amount from the final tally of its NDC. We discuss how these approaches influence the way to make corresponding adjustments and to avoid ‘double counting’. The first one leads to ‘target/budget-based accounting’, the second one to ‘emission-based accounting’. For mitigation outside the scope of the host Party's NDC, we propose using a tally-based interpretation of ITMO use, as opposed to the target-based variety used in the 1997 Kyoto Protocol, and stress the need for additionality testing. This interpretation allows for mandatory corresponding adjustments for all ITMO usage, while the host Party NDC level remains unchanged. A buffer registry is created for corresponding non-NDC adjustments of the selling party.

Key policy insights

• Under the Paris Agreement, transfers of emissions units between two countries through the Article 6 mechanisms need a corresponding adjustment on both sides to prevent double counting.

• Corresponding adjustments can be applied either to emissions targets under NDCs or measured emissions levels.

• The transfer of emissions reduction credits generated outside an NDC should lead to a corresponding adjustment of a buffer registry of the selling country, but not its emissions level/NDC target. Such credits should only be generated if additionality of the reductions is shown.

     

Good practice policies to bridge the emissions gap in key countries

One key aspect of the Paris Agreement is the goal to limit the global average temperature increase to well below 2 °C by the end of the century. To achieve the Paris Agreement goals, countries need to submit, and periodically update, their Nationally Determined Contributions (NDCs). Recent studies show that NDCs and currently implemented national policies are not sufficient to cover the ambition level of the temperature limit agreed upon in the Paris Agreement, meaning that we need to collectively increase climate action to stabilize global warming at levels considered safe. This paper explores the generalization of previously adopted good practice policies (GPPs) to bridge the emissions gap between current policies, NDCs ambitions and a well below 2 °C world, facilitating the creation of a bridge trajectory in key major-emitting countries. These GPPs are implemented in eleven well-established national Integrated Assessment Models (IAMs) for Australia, Brazil, Canada, China, European Union (EU), India, Indonesia, Japan, Russia, South Korea, and the United States, that provide least-cost, low-carbon scenarios up to 2050. Results show that GPPs can play an important role in each region, with energy supply policies appearing as one of the biggest contributors to the reduction of carbon emissions. However, GPPs by themselves are not enough to close the emission gap, and as such more will be needed in these economies to collectively increase climate action to stabilize global warming at levels considered safe.     

The global impacts of US climate policy: a model simulation using GCAM-TU and MAGICC

To assess the potential impacts of the US withdrawal from the Paris Agreement, this study applied GCAM-TU (an updated version of the Global Change Assessment Model) to simulate global and regional emission pathways of energy-related CO₂, which show that US emissions in 2100 would reduce to ?2.4?Gt, ?0.7?Gt and ?0.2?Gt under scenarios of RCP2.6, RCP3.7 and RCP4.5, respectively. Two unfavourable policy scenarios were designed, assuming a temporary delay and a complete stop for US mitigation actions after 2015. Simulations by the Model for the Assessment of Greenhouse-gas Induced Climate Change (MAGICC) indicate that the temperature increase by 2100 would rise by 0.081°C–0.161°C compared to the three original RCPs (Representative Concentration Pathways) if US emissions were kept at their 2015 levels until 2100. The probability of staying below 2°C would decrease by 6–9% even if the US resumes mitigation efforts for achieving its Nationally Determined Contribution (NDC) target after 2025. It is estimated by GCAM-TU that, without US participation, increased reduction efforts are required for the rest of the world, including developing countries, in order to achieve the 2°C goal, resulting in 18% higher global cumulative mitigation costs from 2015 to 2100.

Key policy insights

• President Trump’s climate policies, including planned withdrawal from the Paris Agreement, cast a shadow on international climate actions, and would lower the likelihood of achieving the 2°C target.

• To meet the 2°C target without the US means increased reduction efforts and mitigation costs for the rest of the world, and considerable economic burdens for major developing areas.

• Active state-, city- and enterprise-level powers should be supported to keep the emission reduction gap from further widening even with reduced mitigation efforts from the US federal government.

     

The Paris Agreement and next steps in limiting global warming

The Paris Climate Agreement sets out an aggressive goal of limiting global average warming to well below 2 °C. As a first step, virtually all countries have put forth greenhouse gas emission reduction pledges in the form of nationally determined contributions, or NDCs, for the 2030 timeframe. Our analysis looks beyond the NDCs to explore potential post-2030 regional emissions reduction participation and ambition. For each scenario, we examine the implications for global emissions and long-term temperature. We then evaluate the regional consequences for energy systems and ensuing costs. We conclude by reflecting on the additional global abatement costs of tightening temperature goals. Overall, this study provides a multidimensional characterization of the scale of regional effort supporting climate outcomes, details important to decision-makers as they consider mid-century emissions targets, and long-run climate objectives.     

The impact of the US retreat from the Paris Agreement: Kyoto revisited?

The United States’ decision to withdraw from the Paris Agreement (pending possible re-engagement under different terms) may have significant ramifications for international climate policy, but the implications of this decision remain contested. This commentary illustrates how comparative analysis of US participation in multilateral environmental agreements can inform predictions and future assessments of the decision. We compare and contrast US non-participation in the Kyoto Protocol and the Paris Agreement, focusing on four key areas that may condition the influence of US treaty decisions on international climate policy: (i) global momentum on climate change mitigation; (ii) the possibility of US non-participation giving rise to alternative forms of international collaboration on climate policy; (iii) the timing and circumstances of the US decision to exit; and (iv) the influence of treaty design on countries’ incentives to participate and comply. We find that differences across the two treaties relating to the first three factors are more likely to reduce the negative ramifications of US withdrawal from the Paris Agreement compared to the Kyoto Protocol. However, the increased urgency of deep decarbonization renders US non-participation a major concern despite its declining share of global emissions. Moreover, key design features of the Paris Agreement suggest that other countries may react to the US decision by scaling back their levels of ambition and compliance, even if they remain in the Agreement.

Key policy insights

• Increasing global momentum on mitigation since 1997 means that US withdrawal from the Paris Agreement is potentially less damaging than its non-participation in the Kyoto Protocol

• Despite the declining US share of global emissions, greater urgency of deep decarbonization means that the non-participation of a major player, such as the US, remains problematic for global cooperation and achieving the Paris Agreement’s goals

• Differences in the design of the Kyoto Protocol and Paris Agreement suggest that US non-participation is more likely to prompt reluctant countries to stay within the Paris framework but reduce levels of ambition and compliance, rather than exit the Agreement altogether

     

《巴黎协定》下市场机制建设中的风险与对策

《巴黎协定》（《协定》）第6条设立了合作方法和可持续发展机制两种市场机制。受国家自主贡献（NDC）减排目标多样性和未来减排努力不确定性等因素的影响,《协定》下市场机制在设计和实施中面临着巨大的风险和挑战,主要包括缺乏稳健的核算规则、不恰当的额外性评估带来的环境完整性风险以及经济激励下缔约方不积极扩大减排目标覆盖范围、提高减排行动力度的风险。为了降低风险给全球减排行动可能带来的负面影响,必须建立稳健的核算规则,在额外性评估中合理考虑东道国NDC下的减排承诺,并通过设立参与资质要求等方式确保市场机制促进缔约方扩大减排目标覆盖范围。建议中国结合国内碳市场的发展现状,从识别《协定》下市场机制对我国的要求和影响、进行相关能力建设、设立严格的监管措施和建立所需机构等方面入手,为我国有效参与做好充分准备。     

The Regensburg Model: reference values for the (I)NDCs based on converging per capita emissions†

A core question still remains after the Paris Agreement: who receives how much of the remaining CO₂ budget (resource/burden/effort sharing), so that the increase in the global average temperature is kept to well below 2°C above pre-industrial levels? If converging per capita emissions serve as a possible answer to this question, the discussion focuses primarily on the approach ‘Contraction and Convergence’ (C&C). The Regensburg Model now offers a further option for the mathematical implementation of converging per capita emissions. The authors identify features common to C&C and differences from C&C. They show that, of the convergence models they examined, the Regensburg Model is the most favourable option for industrialized countries.

Policy relevance

In politics, the concept of converging per capita emissions is often accepted at the abstract level. Civil society in particular can then take politicians at their word wherever they take values calculated using the Regensburg Model as points of reference; then prosperous developed countries in particular whose nationally determined contributions do not come up even to these reference values will find it difficult to justify their contributions.     

Environmental integrity of international carbon market mechanisms under the Paris Agreement

The Paris Agreement establishes provisions for using international carbon market mechanisms to achieve climate mitigation contributions. Environmental integrity is a key principle for using such mechanisms under the Agreement. This paper systematically identifies and categorizes issues and options to achieve environmental integrity, including how it could be defined, what influences it, and what approaches could mitigate environmental integrity risks. Here, environmental integrity is assumed to be ensured if the engagement in international transfers of carbon market units leads to the same or lower aggregated global emissions. Four factors are identified that influence environmental integrity: the accounting for international transfers; the quality of units generated, i.e. whether the mechanism ensures that the issuance or transfer of units leads to emission reductions in the transferring country; the ambition and scope of the mitigation target of the transferring country; and incentives or disincentives for future mitigation action, such as possible disincentives for transferring countries to define future mitigation targets less ambitiously or more narrowly in order to sell more units. It is recommended that policy-makers combine several approaches to address the significant risks to environmental integrity.

Key policy insights

• Robust accounting is a key prerequisite for ensuring environmental integrity. The diversity of nationally determined contributions is an important challenge, in particular for avoiding double counting and for ensuring that the accounting for international transfers is representative for the mitigation efforts by Parties over time.

• Unit quality can, in theory, be ensured through appropriate design of carbon market mechanisms; in practice, existing mechanisms face considerable challenges in ensuring unit quality. Unit quality could be promoted through guidance under Paris Agreement Article 6, and reporting and review under Article 13.

• The ambition and scope of mitigation targets is key for the incentive for transferring countries to ensure unit quality because countries with ambitious and economy-wide targets would have to compensate for any transfer of units that lack quality. Encouraging countries to adopt ambitious and economy-wide NDC targets would therefore facilitate achieving environmental integrity.

• Restricting transfers in instances of high environmental integrity risk – through eligibility criteria or limits – could complement these approaches.

     

巴黎气候会议对全球长期目标的新发展

巴黎气候会议（COP21）达成了包括《巴黎协定》在内的重要成果,丰富和深化了应对气候变化的一揽子长期目标。1.5℃温升控制目标意味着全球管控气候风险的政治意愿得到强化,减缓温室气体排放的路径得到初步勾勒。在未来的科学评估和政治谈判中,全球各区域甚至是各个排放大国的排放空间、排放路径和减缓需求将会进一步清晰化和定量化,还会丰富和深化自上而下的国际气候合作规则,结合当前以国家自主决定贡献（INDC）为特征的、主要以自下而上方式推进全球气候治理的新模式,将对发展中国家、尤其是发展中排放大国的排放配额与发展空间产生重要影响,并进一步影响各国制定其国家贡献目标与行动的自主性。     

The Paris warming targets: emissions requirements and sea level consequences

The Paris Agreement states that, relative to pre-industrial times, the increase in global average temperature should be kept to well below 2 °C and efforts should be made to limit the temperature increase to 1.5 °C. Emissions scenarios consistent with these targets are derived. For an eventual 2 °C warming target, this could be achieved even if CO₂ emissions remained positive. For a 1.5 °C target, CO₂ emissions could remain positive, but only if a substantial and long-lasting temperature overshoot is accepted. In both cases, a warming overshoot of 0.2 to 0.4 °C appears unavoidable. If the allowable (or unavoidable) overshoot is small, then negative emissions are almost certainly required for the 1.5 °C target, peaking at negative 1.3 GtC/year. In this scenario, temperature stabilization occurs, but cumulative emissions continue to increase, contrary to a common belief regarding the relationship between temperature and cumulative emissions. Changes to the Paris Agreement to accommodate the overshoot possibility are suggested. For sea level rise, tipping points that might lead to inevitable collapse of Antarctic ice sheets or shelves might be avoided for the 2 °C target (for major ice shelves) or for the 1.5 °C target for the West Antarctic Ice Sheet. Even with the 1.5 °C target, however, sea level will continue to rise at a substantial rate for centuries.     

National contributions to climate change mitigation from agriculture: allocating a global target

Globally, agriculture and related land use change contributed about 17% of the world’s anthropogenic GHG emissions in 2010 (8.4 GtCO₂e yr^?1), making GHG mitigation in the agriculture sector critical to meeting the Paris Agreement’s 2°C goal. This article proposes a range of country-level targets for mitigation of agricultural emissions by allocating a global target according to five approaches to effort-sharing for climate change mitigation: responsibility, capability, equality, responsibility-capability-need and equal cumulative per capita emissions. Allocating mitigation targets according to responsibility for total historical emissions or capability to mitigate assigned large targets for agricultural emission reductions to North America, Europe and China. Targets based on responsibility for historical agricultural emissions resulted in a relatively even distribution of targets among countries and regions. Meanwhile, targets based on equal future agricultural emissions per capita or equal per capita cumulative emissions assigned very large mitigation targets to countries with large agricultural economies, while allowing some densely populated countries to increase agricultural emissions. There is no single ‘correct’ framework for allocating a global mitigation goal. Instead, using these approaches as a set provides a transparent, scientific basis for countries to inform and help assess the significance of their commitments to reducing emissions from the agriculture sector.

Key policy insights

• Meeting the Paris Agreement 2°C goal will require global mitigation of agricultural non-CO₂ emissions of approximately 1 GtCO₂e yr^?1 by 2030.

• Allocating this 1 GtCO₂e yr^?1 according to various effort-sharing approaches, it is found that countries will need to mitigate agricultural business-as-usual emissions in 2030 by a median of 10%. Targets vary widely with criteria used for allocation.

• The targets calculated here are in line with the ambition of the few countries (primarily in Africa) that included mitigation targets for the agriculture sector in their (Intended) Nationally Determined Contributions.

• For agriculture to contribute to meeting the 2°C or 1.5°C targets, countries will need to be ambitious in pursuing emission reductions. Technology development and transfer will be particularly important.