Assessing national net-zero progress to enhance actions


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Assessing national net-zero progress is crucial for bridging the gap toward global climate target
The imperative to achieve net-zero emissions has been underpinned by climate science and has been recognized by the global community. The latest Sixth Assessment Report of the Intergovernmental Panel on Climate Change shows that in order to limit the warming to 1.5 • C by the end of the century, with minimal or no overshoot, all mitigation pathways require achieving net-zero CO 2 emissions in the 2050s [1]. Policymakers at various levels, including national, subnational, and corporate, are setting net-zero pledges that align with these global objectives, thereby reflecting their commitment to climate action. As of June 2023, 149 countries have proposed net-zero targets [2], covering 92% of global GDP, 88% of global greenhouse gas emissions, and 89% of the global population. Achieving net-zero emissions has become synonymous with climate ambitions and a central principle of climate action to achieve longterm temperature goals with broad consensus.
As net-zero is currently the leading framework and guideline for global mitigation, evaluating the national net-zero progress enables an effective and transparent track of the current global efforts. Yet, review, accountability, and reporting mechanisms for national emission reduction actions under the Paris Agreement need to be strengthened, leaving the gap to be filled by progress assessments conducted by academia. Unlike the top-down legal bounds under the Kyoto Protocol, the Paris Agreement established a bottom-up governance mechanism, which only requires parties to voluntarily make commitments and update regularly. A considerable number of countries have yet to develop detailed strategies to fulfill their net-zero pledges. Their long-term goals frequently lack the necessary backing of immediate measures, giving rise to doubts about the sincerity of these commitments and the possibility of greenwashing. Performing a progress assessment makes it possible to evaluate whether a country's pledges, actions, and outcomes are aligning with an effective path to net zero.
The progress assessment provides a comprehensive picture of the extent to which national progress aligns with the global warming objective. The current emission gap lies among four dimensions: the end-of-century warming targets stipulated by the Paris Agreement, national pledges, current national policy measures, and policy outcomes [3]. These gaps could lead to the failure of both national and global targets if left unsolved. The analysis of national climate commitments and actions concludes that current policy measures, national determined contributions (NDCs), and national carbon neutrality targets will respectively reduce the best-estimated global average temperature rise by the end of the century to 2.9 • C-3.2 • C, 2.4 • C-2.9 • C and 2.0 • C-2.4 • C [4], still not enough to reach the 1.5 • C target. Therefore, the assessment ensures accountability, provides signals of where we are, and guidance for transformational change [5].
Furthermore, the progress assessment plays the role of a pacemaker for dynamically promoting national ambitions. It guides countries with currently insufficient ambitions toward self-reinforcing climate transition pathways to gradually converge to the trajectory consistent with the Paris Agreement. The findings of the progress assessment could serve as a valuable data source for the Global Stocktake (GST). Under the Paris Agreement, parties are driven to increase their mitigation efforts through the GST mechanism (figure 1) [6]. The GST aggregates the implementation of national NDCs to assess how far the world as a whole is from meeting the Paris Agreement goals [7]. The insights can inform the national policy agenda for the next round of NDCs updates, forming a ratchet-up mechanism [8]. Thus, countries strengthen climate ambition and action in a nationally independent manner, gradually approaching the path consistent with the Paris Agreement. Under this mechanism, the results of net-zero progress assessment could be used as an important input of GST, thereby exerting influence on countries. It participates in the decision-making procedure of the international community, increasing countries' ambitions and urging them to fulfill their commitments.
The ongoing expansion of the proposed net-zero targets presents a promising opportunity to realize the Paris Agreement goals. The question is, whether the national net-zero pledges are credible, equitable, and robust, whether current actions are sufficient to support the pledges, and whether the outcomes so far turn out to be on track with a validated pathway toward the long-term goals. We believe that a dynamic progress assessment provides an overview of how countries are individually and collectively doing in the context of net zero.

Current assessments primarily focus on the targets and effects, and neglect actions
As for the scope, existing national net-zero progress assessments fall broadly into two categories. One type of them focuses on the target text itself, emphasizing the form and key elements of net-zero commitments. The Climate Watch [9], CAT [10], and Net Zero Tracker [2] conduct a text analysis and systematic classification statistics on the target year, coverage, and legal effect of the goals of national net-zero pledges. Scholars [11][12][13] further proposed several important attributes that an effective and credible net-zero target should have, which could be potentially evaluated, including comprehensiveness of coverage; environmental and social integrity of carbon removal and carbon offset; and consistency of wider ecological targets; the embodiment of adequacy and fairness; and the clarity of specific roadmaps, etc. Another form of assessment [10,14] focuses on the effects of national net-zero pledges and anticipated emissions and warming as a representative measure. As a typical instance, the United Nations Environment Program releases an annual emission gap report to estimate the global warming impact of national climate commitments and mitigation measures [15].
However, most progress assessments fail to adequately prioritize current climate actions. In using the term 'action' , we are referring to the crucial connection between commitments and their effects. Ideally, national net-zero targets will be translated into policy documents and laws. The country will regularly publish progress reports, and targets will steadily increase in strength over time. Achieving net zero requires immediate action. No matter how ambitious the goals are, they can be undermined by insufficient actions [16]. To ensure more comprehensive and effective climate action information, it is necessary to expand the assessment scope. Climate Action Monitor 2022 [17] and the State of Climate Action 2022 [18] are promising initial steps toward understanding the current state of climate action, yet a systematic and quantitative evaluation system still needs to be in further discussion and development.

Essential elements to be concerned with when assessing practical actions
Here, we present several essential aspects of climate action implementation and support that require consideration, including legislation and policies, technologies, finance, and regulatory mechanism (figure 2).

Legislation and policies
Incorporating national net-zero pledges into climate legislation and implementing subnational and industrial policies to support the national goals are both critical steps to improve confidence in net-zero targets [19]. An ideal progress assessment would examine whether countries have done such formulations as well as whether past and current action deviates materially from the existing legislation and policies. By identifying and demonstrating effective legislation and policies taken to date, it helps to drive the practices with good economic, social, and environmental benefits. However, countries at different development stages may have different inclinations for including climate pledges in laws or policy systems. Therefore, during the evaluation process, a one-size-fits-all principle needs to be avoided. Assessments need to be conducted based on specific national circumstances and the principle of common but differentiated responsibilities and respective capabilities.

Technologies
Zero-carbon energy systems, efficient end-use measures, and carbon removal technologies can reduce the cost of mitigation actions. Competitive green technologies would replace the original technologies in the market. The diffusion of innovations would drive significant changes in the economic and social environment and facilitate the establishment of new technical standards and industrial chain structures. By comprehensively demonstrating the progress of mitigation technologies that generate socioeconomic benefits, it serves as a model and reference for the mitigation actions of state and non-state actors by sharing best practices and lessons. The information it provides could promote collective progress and help guide the renewal of national commitments. However, there are still limitations to the clarity of certain industrial progress. For instance, clearer signals can be provided in the power sector and passenger transport electrification, but for building and agriculture sectors, there are still certain challenges in matching technical requirements to 1.5 • C and 2 • C targets.

Finance
Climate finance is an important means to support the implementation of the Paris Agreement. Increasing climate funds, creating new financial instruments and markets, and controlling the risk of stranded assets are essential ways of climate finance to catalyze capital support for the low-carbon transition [16]. Under the requirement of net zero, developing countries urgently need to control carbon emissions growth, and climate finance is essential in assisting their actions to address climate change. Developed countries pledged at the 15th Conference of the Parties (COP) in Copenhagen to mobilize at least US$100 billion a year from public and private sources to provide climate finance to developing countries by 2020 [20]. But so far their funds remained inconsistent with this goal. At COP27, the parties reached an agreement to provide loss and damage funds for vulnerable countries hit hard by climate disasters, but implementation is still pending [21]. Limited to the text of the Paris Agreement, financing objectives are too broad and general, making it difficult to provide clear guidance for climate investment and financing actions [22]. The lack of credibility of climate finance commitments will not only affect the effectiveness of the Paris Agreement but also affect the ability of developing countries to fulfill their commitments, further affecting the credibility of mitigation commitments [23]. Therefore, the status of climate finance needs to be considered in the assessment of carbon neutrality progress, including the insufficiency, credibility, and equity of funding [24].

Regulatory mechanisms
A legally effective review and regulatory system is an important feedback means to support the implementation of the national net-zero target. It can provide necessary information for the update of the target and the government's future decision-making. The existing regulations for net-zero targets in various countries focus on the accounting of emission reductions, the impact of mitigation and adaptation measures taken, and the construction of policies and regulations. Beyond that, mechanisms for managing large-scale carbon removal and carbon offset deployments still need to be developed to ensure a balance between emissions and removal as well as the environmental integrity of any deployments of carbon removal schemes. Countries can be assisted to have clear assignments of responsibility, prudent risk management, and transparent progress toward netzero emissions with the implementation of a regulatory structure for monitoring and evaluating carbon neutrality.

Potential concerns when implementing assessment
While the necessity and essential elements of net-zero progress assessments are relatively clear, there are still numerous challenges remaining when implementing actual assessments. (1) Data basis. The net-zero progress assessment has a complex matrix, which has high requirements for extensive data access, granularity, and timeliness. With the continuous improvement of basic database construction, databases such as the Climate Action Monitor 2022 [17] and the State of Climate Action 2022 [18] could be valuable sources of information. (2) Time coverage. The expectation of future legislation and policies, technologies, finance, and regulations is usually limited for the short term, making it challenging to match the action progress to the mid-century pledge within the time frame. A possible solution is to use scientific and transparent methods to extrapolate current actions beyond the timescales to align with long-term netzero goals. (3) Political feasibility. The national netzero progress assessment may easily lead to judgments on the appropriateness and activeness of government actions, which could be controversial to the 'bottomup' philosophy of the Paris Agreement. Thus, it may be difficult to directly introduce the assessment mechanism into the Paris Agreement framework. However, comprehensive reporting to parties under the United Nations Framework Convention on Climate Change requires specific data on national climate actions. The results of the progress assessment could be included as an important source of information, thus it plays a role in the political process through the GST mechanism and the climate negotiations.

Data availability statement
No new data were created or analyzed in this study.