Evaluating long-term low emission development strategies and implications for the remaining global carbon budget

ABSTRACT The imperative to halt global warming extends beyond human boundaries, intertwining with the urgent need to achieve net-zero emissions. To this end, the Paris Agreement (PA) states that all Parties should strive to formulate their Long-Term Low Greenhouse Gas Emission Development Strategies (LT-LEDS). This article comprehensively reviews the LT-LEDS submitted to the United Nations Framework Convention on Climate Change (UNFCCC) by 53 Parties (representing 75% of global emissions) as of September 23rd, 2022. First, it conducts an analysis of the quality and completeness of the LT-LEDS. The findings of this analysis highlight the need for improvement in the reported information, particularly to improve the clarity of the information presented and the monitoring of progress towards the objective of each LT-LEDS. Furthermore, the study confirms the noticeable absence of reference to the principles of equity, and common but differentiated responsibilities and respective capabilities in the light of different national circumstances. Yet these principles should frame climate action within the PA. Second, this article estimates the carbon budget to be utilized by the Parties that have integrated net-zero emission (NZE) targets within their LT-LEDS. The analysis reveals that this group of Parties (i.e. those reporting on LT-LEDS and those with NZE targets), currently encompasses 37% of the global population and is responsible for 62% of global emissions. If these NZE targets are met, the group is projected to consume a total of 431 GtCO2. This value notably exceeds the threshold of 400 GtCO2, exceeding the remaining global carbon budget estimated by the IPCC to be compatible with a 67% likelihood to achieve a temperature increase objective of 1.5°C. Key policy insights: To achieve the objectives of the PA, it is necessary for all countries to develop and implement their LT-LEDS, and for the 53 countries that have already submitted them to enhance the quality and comprehensiveness of the reported information and to improve the monitoring of progress towards NZE targets. To achieve the long-term objective of limiting the global temperature increase to 1.5°C, more countries need to actively engage in formulating and implementing NZE commitments. It is also imperative to increase the level of ambition in the existing NZE commitments, particularly those formulated by developed countries. All LT-LEDS, encompassing both present submissions and those anticipated in the future, should be formulated in the light of equity considerations, and meticulously assess the share of the global carbon budget that will be allocated to the LT-LEDS’ net-zero CO2 commitments. The analysis of net-zero CO2 commitments reveals that the existing NZE targets set by developed nations entail a carbon budget consumption significantly exceeding their equitable share, while those formulated by less developed countries remain notably below their due allocation. This divergence could potentially limit the capacity of the latter group to foster their development, compounded by the challenges of addressing climate change impacts. Examination of the current NZE commitments underscores that the current trajectory of emission reductions lacks a comprehensive framework to instigate the transformative changes required to achieve the ambitious mitigation objectives of the Paris Agreement. Consequently, there is an imperative for more detailed and comprehensive long-term visions at the national level, which will serve as guidance for short-term policy decisions and effectively prioritize the fundamental structural shifts needed.


Introduction
The pursuit of a net-zero greenhouse gas emissions target is perhaps the most ambitious collective endeavour in human history and requires a comprehensive transformation of economies and societies on a global scale.Currently, various initiatives and campaigns are underway at national, sub-national, municipal, and corporate levels to promote the decarbonization of economies.An example of such efforts is the 'Race to Zero' campaign, which operates within the UNFCCC and encompasses a diverse array of initiatives tailored to different non-governmental actors (UNFCCC, 2022a).At the national level, several countries have announced net-zero emission targets, while others have incorporated this target into policy documents or integrated it within their legislative frameworks (Black et al., 2021).
In the context of multilateral climate change processes, the Paris Agreement (PA) serves as the current framework of action, bringing all nations into a common cause to undertake ambitious endeavours in combating climate change and adapting to its impacts.Effectively implementing this agreement requires economic and social transformations grounded in the best available science.Article 2 of the PA establishes that climate action should be guided by the principles of equity and 'common but differentiated responsibilities and respective capabilities in the light of different national circumstances' (CBDR&RC).Article 4 mandates Parties 'to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century, on the basis of equity, and in the context of sustainable development and efforts to eradicate poverty' (United Nations, 2015).Nonetheless, within the UNFCCC a consensus has never been reached on how to operationalize equity.Yet, despite a failure to operationalize these principles, both equity and CBDR&RC consistently feature in discourse and agreements of the UNFCCC.
The Paris Agreement (PA) operates within a 5-year cycle, encouraging countries to progressively enhance their climate action efforts.As part of this process, countries submit their Nationally Determined Contributions (NDCs), which outline their planned actions to reduce their greenhouse gas emissions and achieve the longterm temperature stabilization goal defined in the Agreement.To strengthen the framework for long-term objectives, the PA invites countries to formulate and submit their mid-century Long-Term Low Greenhouse Gas Emission Development Strategies (LT-LEDS).The LT-LEDS provide the long-term horizon to the NDCs.However, unlike NDCs, the formulation of LT-LEDS is not mandatory, and there are no established guidelines in place for their development.Nevertheless, they can serve as a valuable tool to align the long-term mitigation goals of the PA with the medium-term focus of the NDCs, offering a vision and direction for future development (Waisman et al., 2019).
In accordance with Article 4, Paragraph 19, of the PA: 'All Parties should strive to formulate and communicate their Long-Term Low Greenhouse Gas Emission Development Strategies, mindful of Article 2 taking into account their common but differentiated responsibilities and respective capabilities, in the light of different national circumstances' (United Nations, 2015).
Since the ratification of the PA until September 23rd, 2022, only a total of 53 Parties, comprising 52 countries and the European Union (EU27), had submitted their LT-LEDS to the UNFCCC Secretariat (UNFCCC, 2022b).This article aims to comprehensively analyse the LT-LEDS communicated within this timeframe.The evaluation focuses on the information included in each LT-LEDS to facilitate meaningful comparisons.Key aspects examined and then used to calculate their implications for the Global Carbon Budget include their net-zero emission (NZE) pledges and commitments as well as their implied emission pathways.
It is noteworthy that the elaboration and communication of LT-LEDS is subject to the discretion of each individual Party.This implies that the development and submission of LT-LEDS are not obligatory but rather actions to be encouraged.Furthermore, the ambition level of these strategies is also determined by each Party independently.The UNFCCC only plays an advisory role, providing guidance to countries on actions that can facilitate the transition towards a carbon-neutral planet.
Given the absence of agreed regulations or guidelines regarding the content or structure of the LT-LEDS, various authors and institutions have published recommendations aimed at policymakers responsible for planning and preparing LT-LEDS.For instance, the Climate Change Expert Group working through Organization for Economic Co-operation and Development (OECD) and the International Energy Agency (IEA) released two guidance documents.The first guide outlines key issues to establish LT-LEDS (Rocha & Falduto, 2019), while the second provides recommendations for how to align NDCs with LT-LEDS (Falduto & Rocha, 2020).Furthermore, the World Resources Institute (WRI) and the United Nations Development Programme (UNDP) have published a set of working papers that offer policymakers an extensive collection of recommendations for LT-LEDS development (Levin et al., 2018;Elliott et al., 2019;Vener et al., 2019;WRI, 2020).To consolidate these resources, WRI and UNDP prepared a synthesis in the form of the 'Quality Assurance Checklist: For Long-Term Low Greenhouse Gas Emission Development Strategies' (WRI and UNDP, 2021).This is referred to as the 'Checklist' henceforth.In the initial part of this study, the Checklist is utilized to compile and evaluate the information from each country's LT-LEDS.
All of the guidance documents noted above underscore the importance of incorporating the perspective of LT-LEDS into the implementation and the updating of the NDCs.This will ensure the alignment of NDCs with long-term objectives, thus avoiding short-term actions that are not compatible with long-term climate goals for mitigation and adaptation.The guide also addresses aspects related to the good governance of LT-LEDS development processes, offering insights into considerations required during the pre-design, design, post-design, and implementation stages.For example, in setting their long-term mitigation goals, it is recommended that countries consider three key aspects: determining the peak of their emissions; establish their net-zero emissions target year; and how to devise credible and feasible emissions reduction pathways across different sectors of the economy.
Regarding the NZE objectives incorporated in many LT-LEDS, it is necessary to clarify the different types of commitments falling under this category.When referring to net-zero emissions, it means achieving a state of equilibrium between emissions and removals through sinks or carbon capture and storage systems.This equilibrium may pertain solely to CO 2 (net-zero CO 2 emissions), or encompass the entire spectrum of GHGs (net-zero GHG emissions) (Rogelj et al., 2015).According to the latest IPCC report, scenarios compatible with the PA's objectives, entail reaching global net-zero CO 2 by the mid-century and achieving net-zero GHG emissions between one and two decades thereafter (IPCC, 2022).
It is also crucial to bear in mind that limiting global warming to 1.5°C requires keeping cumulative CO 2 emissions below the remaining global carbon budget (RGCB), which stands at 400 GtCO 2 (67% likelihood), until reaching net-zero CO 2 emissions (IPCC, 2021).The concept of the RGCB refers to the maximum cumulative net global anthropogenic CO 2 emissions that would result in limiting global warming to a specific level with a given probability (IPCC, 2021).Monitoring the consumption of the RGCB enables us to assess our proximity to exceeding the long-term temperature objective of the PA (Winkler & Marquard, 2012;Kanitkar & Jayaraman, 2019;Dickau et al., 2022).Extensive literature highlights the historical inequitable distribution of cumulative emissions worldwide (IPCC, 2022;Friedlingstein et al., 2022) and emphasizes the necessity of granting carbon space to developing countries for their development (Rao & Baer, 2012;Winkler et al., 2013;Bruckner et al., 2022).
Returning to the matter of NZE commitments, various recommendations exist regarding the development of 'deep decarbonization pathways' (Waisman et al., 2019;Fujimori et al., 2021) as well as the necessary content of net-zero (Rogelj et al., 2015(Rogelj et al., , 2021;;Levin et al., 2020;Fankhauser et al., 2022).Given the rapid proliferation of these commitments in different domains and the lack of specificity in some cases, the scientific community warns that failure to proceed correctly may result in missing the opportunity to achieve the climate goals (Rogelj et al., 2021).The aforementioned authors, Rogelj and Fankhauser, additionally stress the importance of disclosing the carbon budget associated with each commitment and, within the context of LT-LEDS, justifying them based on the principles of equity and CBDR&RC.These principles must be integrated into the assessment of NZE commitments and the design of LT-LEDS (Lenzi et al., 2021).
The first section of this paper seeks to examine the LT-LEDS communicated until September 23rd, 2022, and systematize the information provided by each of the Parties to enable a comparison of their commitments.Additionally, the analysis aims to offer complementary insights to those presented in the Synthesis Report published by the UNFCCC Secretariat in October 2022 (UNFCCC, 2022c).This analysis is conducted in line with the issue guidance outlined by the Checklist.The subsequent analysis reported on here entails estimating the carbon budget that will be consumed, starting from 2020 and until reaching emissions neutrality, by Parties that have included NZE commitments in their LT-LEDS (taking into account the year committed by each country to achieve it).This estimation enables the calculation of the proportion of the RGCB consumed by these Parties during their target period and consideration of pertinent equity concerns.

Methodology and data
By September 23rd, 2022, a total of 53 Parties submitted their LT-LEDS to the Secretariat of the UNFCCC (UNFCCC, 2022b).The emissions of these 53 Parties contribute to the 75% of the global emissions.Table 1 provides a comprehensive list of the Parties that have communicated their LT-LEDS, as along with the nature of their mitigation commitments.
Out of the 53 Parties that submitted their LT-LEDS to the UNFCCC, only 35 have included NZE targets.Among these, 24 are developed countries, including 14 from the EU27, and 11 are developing countries.Among the developing countries, 6 are categorized as Developing here, 3 are Least Developed Countries (LDCs), and 2 are Small Islands Developing States (SIDS).

Quality assurance of the LT-LEDS submitted to the UNFCCC
Given the absence of established guidelines for the development of LT-LEDS, each Party has devised strategies that vary significantly from one another in terms of pledges and priorities.Consequently, the analysis of the different LT-LEDS submitted has been labour-intensive due to the complexity involved in comparing these strategies.
The analysis and comparison of these strategies were facilitated by the use of the Checklist.The Checklist serves as a tool to assist governments, civil societies, and other stakeholders in the design and revision of the LT-LEDS.It provides a series of guiding questions that help evaluate the quality of an LT-LEDS and its underlying processes.Since LT-LEDS are country-specific, the Checklist is intended to serve as a concise reference guide to be interpreted within the national context.
The Checklist, available in the Supplementary Material (SM) -Annex A, consists of a set of 80 questions divided into three main categories and sections as outlined in Table 2.This document has played a crucial role in testing the quality of each submitted LT-LEDS and facilitating meaningful comparisons between them.In the analysis of the 53 LT-LEDS, all 80 questions from the Checklist were addressed and answered.Annex B (SM) documents and summarizes the complete set of answers.
In addition, the first page of Annex B captures other pertinent information related to the LT-LEDS.This includes the submission date of the LT-LEDS, the share of global CO 2 emissions represented by the respective Party, the quantified emissions goal outlined in the LT-LEDS, and the continual strategy revisions.
In order to conduct a comprehensive quality assessment of each LT-LEDS submitted until September 23rd, 2022, the authors diligently addressed all 80 questions of the Checklist with the information provided by each of the Parties within their strategies.Beginning with Andorra and concluding with Uruguay, the authors systemically categorized their responses to each question as either 'Yes', 'No' or 'Partially' as advised by the Checklist.A 'Yes' indicated that the Party included the relevant information within the strategy, while 'No' indicated its absence.This classification system allowed for a structured comparison of the analysed LT-LEDS, taking into account the substantial variation in information presented across different strategies due to the lack of Developing ' … From 2036 onwards, emissions will decline in absolute terms to a range with a lower limit of 212 MtCO2e and an upper limit of 428 MtCO2e by 2050'.
(Continued ) established guidelines, as mentioned earlier.'Partially' has been used when information was unclear or only part of the question could be answered.An example of the assessment process is provided in Section 1.1, Question 4, 'Does the vision and content of the LT-LEDS consider all appropriate national, sectorial, and/or sub-national data and models such as current GHG emission levels?'.For Fiji, this particular question was assessed as 'Partially' since Fiji's LT-LEDS considers appropriate national data, but lacks the inclusion of sub-national data and models.Furthermore, it explicitly acknowledges that not all sectorial data pertaining to GHG emissions in the LT-LEDS are currently available: ' Most notably, the Fijian Government understands that not all data relating to GHG emissions from the different sectors in the LEDS are currently fully known, nor are all mitigation actions fully investigated' (Ministry of Economy of Fiji, 2018).
The analysis and systematization of the 53 LT-LEDS can be found in Annex B, where a summarized overview of all the responses is presented, categorized by Party and sections.
This method enabled us to concentrate on the core aspects essential for the development of a robust longterm strategy.By using pertinent questions as the initial step in assessing the LT-LEDS, followed by the compilation of the information into an Excel file, the authors successfully evaluated the quality of the submitted strategies.

Estimated carbon budget consumption of the Parties presenting net-zero pledges within their LT-LEDS
The carbon budget concept serves as a valuable tool for establishing NZE targets and monitoring the progress towards achieving them (Dickau et al., 2022).The authors estimated the carbon budget that will be consumed until reaching net-zero emissions by the Parties that made net-zero commitments in their LT-LEDS.This group is composed by 6 developing countries, including China, 5 additional developing countries classified as LDCs or SIDS, and 24 developed Parties.The group of developed Parties includes the EU27 as a whole as well as 14 individual countries within the EU27.The analysis focused predominantly on the collective strategy of the EU27, which aspires to attain climate neutrality by 2050.It's important to note that the distinct net-zero commitments of the 14 EU27 countries were not examined individually in this assessment.This approach was adopted because the EU submits a joint submission encompassing all its member states, making it necessary for all EU27 countries to adhere to the EU27 target.Consequently, the analysis was specifically applied to the netzero commitments of 21 Parties, accounting for the exclusion of the 14 EU27 countries from the 35 total.
Certain developing country Parties have indicated that the fulfilment of their NZE commitments is contingent upon receiving external international funding.This is the case of Cambodia, Colombia, Costa Rica, Fiji, Gambia, the Marshall Islands, Nepal, Nigeria, and Uruguay.
The CO 2 emissions collected in the PRIMAP-hist national historical emissions time series v2.3.1 (1850-2019) were the base of these calculations (Gütschow et al., 2021).Subsequently, the UNEP Pledge Pipeline database (Fenhann, 2022) provided the 2030 emissions reduction commitments, and the year of each country's net-zero emissions target.These parameters were used to forecast the carbon budget consumption of the Parties from 2020 until their projected net-zero emissions year.Table 1 displays these essential parameters.
For the calculations, a linear trajectory was established between the last year with available historical data, namely 2019, and the target year of 2030.A similar approach was applied from 2030 until the year in which each Party committed to achieving net-zero emissions.These calculations were performed for all 21 Parties analysed, enabling the projection of their future carbon budget consumption.It is important to note that the LT-LEDS of each Party do not provide a detailed description of their emissions reduction pathway towards net-zero CO 2 .Therefore, assuming linear mitigation pathways introduces a significant degree of uncertainty when estimating accumulated emissions.
To estimate cumulative emissions per capita (i.e.cumulative emissions divided by the population), the authors used historical population data along with the variant medium scenario of the World Population 2022 Prospects (UNDESA, 2022).

Analysis of the quality assurance of the LT-LEDS submitted to the UNFCCC
As shown in Table 2, all the questions are divided into 3 main categories and sections.Table 3 presents the ratios of each answer per section.The analysis of the results reveals that the majority of LT-LEDS provided information primarily in the '2.4 Sector-Specific Strategies' section, resulting in the highest ratio of completed responses of the Checklist.This outcome can be attributed to the inclusion of comprehensive sector-specific information by most Parties.In contrast, the section with the highest ratio of incomplete answers is '1.3 Monitoring and Review'.This is mainly because many strategies lacked a designated revision period for the LT-LEDS, leading to a lack of detail in addressing these questions.Lastly, the section with the highest ratio of partially completed answers is '1.1 Mandate and Planning', indicating that the information pertaining to the questions in this section was not clearly provided.For instance, in multiple cases, several Parties did not specify if they have incorporated a mandate to implement their LT-LEDS.
Annex B provides a comprehensive overview of the data and characteristics presented in each LT-LEDS.Notably, it shows that the most frequently provided information within each LT-LEDS includes engaging with stakeholders, conducting public consultations, and specifying how the LT-LEDS vision aligns with the goals of the PA.To develop a robust strategy, it is essential for governments and their institutions to demonstrate their support and recognition of the importance of the PA compliance.Moreover, illustrating the connection between their actions and the objectives of the treaty within the LT-LEDS enhances the strength of the overall strategy.
Additionally, out of all the strategies analysed, only 7 (Andorra, Fiji, France, Gambia, Marshall Island, Nigeria, and Tonga) 1 have explicitly specified the necessary resources for revising their LT-LEDS.While many countries have acknowledged the need for a revision every 5 years, most of them have not conducted an evaluation of the required resources needed to effectively carry out the revision of the strategies.
Only 9 countries (Austria, China, France, Indonesia, Latvia, Malta, South Africa, Switzerland, and Uruguay) 2 have explicitly mentioned the principle of CBDR&RC in light of different national circumstances within their strategy.However, it is important to note that the mere mention of this principle does not necessarily indicate its full incorporation it into the design of their strategies.This suggests that most of the countries are not considering this principle when planning and implementing their LT-LEDS.
The analysis reveals that the majority of the Parties have incorporated a statement in their LT-LEDS indicating their alignment with the best available science necessary to accomplish the objectives of the PA.These goals include limiting temperature rise, enhancing adaptive capacity and strengthening climate resilience, and increasing climate finance flows.
At the same time, the base year, the baseline projection, and the target year(s) of their mitigation strategies 3 were also generally included within most of the LT-LEDS.Only 6 Parties (the EU27, Japan, Singapore, South Africa, Tonga, and Norway) did not clearly provide this information.
Contrarily, it is noteworthy that 25 Parties did not provide detailed information on their national circumstances, objectives, priorities, and GHG emission levels within their LT-LEDS. 4This information is considered fundamental when developing a long-term strategy that will impact the country's economy and test its capacity to mitigate and adapt to climate change.The lack of this information may be attributed to the belief that it is already provided in their National Communications and emissions inventories.In total, 15 Parties did not include specific information on this (Australia, China, Fiji, Guatemala, Indonesia, Japan, the Marshall Islands, Morocco, Nepal, the Russian Federation, Singapore, Switzerland, the United Kingdom, the United States, and Uruguay), and among them, 10 Parties did not provide information on their GHG emission levels (Belgium, Canada, the EU27, Finland, Lithuania, Malta, the Netherlands, Norway, Slovakia, and Spain).Notably, this list includes four of the highest CO 2 emitting countries globally, namely China (31%), the EU27 (8.2%), the Russian Federation (4.8%), and the United States (15%), accounting to over 59% of global CO 2 emissions.Therefore, their actions and commitments play a vital role in achieving mitigation goal of the PA.
In conclusion, it is worth highlighting that, on average, 60% of the crucial aspects necessary to develop a comprehensive strategy were incorporated within the LT-LEDS.At the same time, on average, 34% of the information that should have been included was missing, and about 6% of the information was not clearly stated.These numbers indicate that there is room for improvement in the information presented within the LT-LEDS.
On the other hand, upon examining the answers collected in Annex B by Party 5 , it becomes evident that France and Fiji were the countries that, overall, provided more information within their LT-LEDS.This indicates that their strategies were of higher quality as they incorporated nearly all the relevant information according to the Checklist.In contrast, the LT-LEDS submitted by the EU27 provided the least amount of information within the strategy.This could be attributed to the expectation that more detailed strategies would be provided by countries within the EU27 individually, and this LT-LEDS simply summarizes the collective commitments of the EU27 towards achieving climate neutrality by 2050.Lastly, Australia's strategy was the least precise, with a total of 19 'Partially' answers. 6The significant number of 'Partially' response suggests a lack of clarity within Australia's LT-LEDS.
Australia, Belgium, Canada, China, the Czech Republic, the EU27, Guatemala, Lithuania, the Netherlands, Norway, the Russian Federation, Spain, and the United States incorporated less than 50% of the information specified within the Checklist.It is particularly concerning that among these countries, there are some of the largest emitters (China, the EU27, and the United States), as well as a significant number of developed countries (Australia, Belgium, Canada, the Czech Republic, the EU27, Lithuania, the Netherlands, Norway, the Russian Federation, Spain, and the United States).These countries, being more industrialized, are expected to take a greater initiative in reducing their GHG emissions and supporting other developing nations, particularly the LDCs and the SIDS, in addressing the threats and adverse effects of climate change.
Denmark, Fiji, France, New Zealand, and North Macedonia stand out as the Parties that incorporated over 80% of the information outlined in the Checklist.This indicates that they submitted the most comprehensive LT-LEDS.
The use of a checklist for analysing these strategies has proven effective in identifying the strengths and weaknesses of each LT-LEDS.Resources such as this list of questions should be more widely employed during both strategy development and revision processes, as they facilitate a more thorough and systemic approach.
It is also worth mentioning that the countries with greater resources available are paradoxically the ones that, overall, have incorporated the least amount of information within their strategies.Conversely, the developing countries, including LDCs and SIDS, that submitted LT-LEDS, have generally presented more relevant and comprehensive information.
Table 4 below illustrates that, in terms of the percentage of questions answered, 12% of developed countries and 13% of LDCs and SIDS provided more than 80% of the required information to address the Checklist questions.In contrast, none of the other developing countries provided more than 80% of the answers.
When examining the data, it is evident that only 33% of the developed countries that submitted LT-LEDS included less than 50% of the information recommended by the Checklist.Similarly, 17% of the developing countries, including China, also failed to surpass the 50% mark.However, when excluding China and focusing solely on the other developing countries, this percentage drops significantly to 9%.
It is also noteworthy that the percentage of LDCs and SIDS that did not provide sufficient information within their strategies is 0%.This finding reflects the high level of concern exhibited by these groups in their efforts to address and adapt to the challenges and uncertainties posed by climate change.
In conclusion, a significant proportion of both developed and developing countries faced challenges in providing a minimum of relevant information.In contrast, LDCs and SIDS demonstrated commendable performance by presenting the most comprehensive and detailed information overall, as none of these Parties included less than 50% of the information recommended by the Checklist.These outcomes illuminate the proactive stance of LDCs and SIDS countries.Despite potentially constrained resources and capacities for reporting and undertaking such endeavors, these nations vividly recognize the pivotal significance of their commitments.They are acutely aware of how actions like this will intricately shape the trajectory of their nations' futures.Conversely, the performance of developed countries, often seen as torchbearers on the path to achieving net-zero targets and as supporters of developing counterparts, suggests that not all available capacities were utilized to submit a more detailed LT-LEDS.

Results and discussion of the LT-LEDS' implied estimated carbon budget
Table 5 illustrates the estimated carbon budget to be consumed by the 21 Parties selected until achieving netzero CO 2 emissions.The total consumption of these Parties amounts to 431 GtCO 2 , surpassing the value of 400 GtCO 2 which corresponds to the RGCB compatible with the 1.5°C goal (67% likelihood) outlined in AR6 (IPCC, 2021).Notably, these commitments come from only 21 Parties, representing a mere 37% of the global population and less 63% of current GHG emissions.It is alarming that their combined commitments already exceed the RGCB, underscoring the significant gap between these pledges and the feasibility of achievement the 1.5°C goal, especially considering the lack of action by other countries to design, implement, and report on LT-LEDS.China stands out in the emissions ranking and deserves a special mention.Within its LT-LEDS, China has committed to achieving carbon neutrality before 2060.Table 5 presents the estimated carbon budget that China would consume if it was to achieve net-zero emissions by 2060.However, if the country manages to reach carbon neutrality in 2055, or even earlier, by 2050, the estimated carbon budget would decrease by 10% and 20%, respectively.It's important to note that for every delay in reaching the net-zero target year, there is an associated increase in carbon budget consumption that other countries might need to use for their safe and sustainable development.This principle holds true for countries that have not set targets at all as well.
Cumulative emissions per capita provide a basis for comparing countries with different population sizes and across different country groupings by level of development.In Table 5, the carbon budget per capita between 2020 and the year of reaching net-zero emissions (calculated as cumulative emissions divided by cumulative population according to medium variant UNDESA scenario (UNDESA, 2022)) is compared with the cumulative emissions per capita during the historical periods of 1990-2019 and 1950-2019.However, it is essential to acknowledge that there is ongoing debate and controversy regarding the starting point for historical responsibility (Neumayer, 2000;Müller et al., 2009;Höhne et al., 2011).Some authors maintain that historical responsibility must be traced back to the beginning of the industrial revolution (Cao, 2008;Kanitkar et al., 2013).In contrast, other authors argue that it was not until the 1990s that the international community fully recognized the threat of climate change, and became fully responsible for GHG emissions (Baer et al., 2008;German Advisory Council on Global Change, 2009;Parikh & Parikh, 2009).This period coincided with the publication of the IPCC's First Assessment Report and the approval and ratification of the UNFCCC.It should also be noted that many countries consider 1990 as their base year.
Significant variations are evident in the carbon budget per capita associated with the analysed net-zero commitments.Among the countries studied, only 8 (Cambodia, Colombia, Costa Rica, Fiji, Gambia, the Marshall Islands, Nepal, and Nigeria) have carbon budgets below the benchmark of 1.47 tCO 2 per capita per year, which would be the allocation per person if the 400 GtCO 2 of the RGCB were to be distributed equally per capita in the period 2020-2050, considering the projected changes in the world population based on the medium variant population scenario from UNDESA (UNDESA, 2022).Table 5 also illustrates that, in the 1990-2019 period, these countries also exhibit historical cumulative emissions per capita well below the global average and they are even lower when considering the historical period 1950-2019.Consequently, if besides considering equality, we consider the differences in historical responsibility of countries, these 8 countries should have a carbon budget per capita, between 2020 and their net-zero pledge, greater than 1.47 tCO 2 .Beyond this, the number would be even greater if we considered additional allocation of carbon budget countries with lower capacity to deal with climate change mitigation and adaptation measures.An indicator of capacity can be the GDP per capita, for which this group of countries, with the exception of Costa Rica, is below the world average.
When examining the group of 5 countries classified as LDCs or SIDS, it is observed that their carbon budget per capita, from 2020 until achieving net-zero emissions, amounts to 0.32 tCO 2 .Although this figure is slightly higher than the emissions per capita during the historical 1990-2019 period, which stood at 0.27 tCO 2 , it still remains well below the 1.47 tCO 2 global benchmark figure.Conversely, when comparing the groups of countries in Table 5, developed nations, characterized by higher GDP per capita and subsequently augmented capacities, envision consuming a proportionately larger share of the RGCB in comparison to their counterparts (with the exception of China).This trajectory raises concern, as it implies that a disproportionately greater carbon allocation is being claimed by developed nations (that representing the 12% of the global population Table 5. Estimation of the carbon budget consumed by the 21 Parties that have submitted net-zero pledges within their LT-LEDS.The annualized carbon budget per capita between 2020 and the year of net zero is calculated by dividing the cumulative emissions by the cumulative population over this time frame.Population data has been sourced from the World Population Prospects (UNDESA, 2022), using medium variant future population scenarios.The carbon budget per capita has also been compared to the cumulative emissions per capita of the historical periods of 1990-2019 and 1950-2019.The two last columns display the GDP PPP per capita from World Bank (World Bank, 2022) and the SDG index from the Sustainable Development Report (Sachs et al., 2019) are taking 35% of the RGCB), leaving insufficient room for the others.This apparent disparity calls into question the responsibility of developed countries to take the leadership on this trajectory.By taking a greater carbon space than warranted, they could impede the progress of others in achieving their net-zero aspirations, thereby revealing a discord between expected leadership and equitable collaboration.
When discussing equity, it is crucial to consider a country's right to development.Developing countries such as Cambodia, Gambia, and Nigeria face significant development challenges, making it difficult to provide their populations with the necessary infrastructure for progress while also maintaining low emissions per capita.It is important to note that countries like Nigeria have substantial proportions of their population living in extreme poverty (31%), limited access to safely managed drinking water (22%), and a primary reliance on clean fuels and technology (15%) (UN-DESA, 2022).Among the 21 countries analysed, the ones that remain with the most challenges to achieve the 17 Sustainable Development Goals (SDGs) are Nigeria and Gambia, with an SDG Index of 46.4 and 55, respectively (Sachs et al., 2019).
Table 5 provides further insights by revealing that countries with a carbon budget per capita per year exceeding 1.47 GtCO 2 , from 2020 until their net-zero pledge year, have a history of accumulated emissions per capita surpassing the global average during the periods of 1990-2019 and 1950-2019.With the sole exception of China, all these countries boast GDP per capita higher than the world average suggesting greater capacity to act on climate change.Based on this, if aside from incorporating the equality criterion, we also consider other dimensions of equity like capacity and historical responsibility, it becomes apparent that the carbon budget required for these countries to achieve net-zero emissions would be significantly below 1.47 tCO 2 .
When making these comparisons, it is clear that these 10 developed Parties, stated in Table 5, are planning efforts to reduce emissions in the coming decades.However, these developed countries, with significant historical responsibility, do not manage to limit emissions below the benchmark 1.47 tCO 2 per capita per year based on the commitments outlined in their LT-LEDS.The range extends from historical average annual emissions per capita of 11.98 tCO 2 to a carbon budget per capita of 4.23 tCO 2 from 2020 until they achieve net-zero targets.Yet a carbon budget per capita of 4.23 tCO 2 is far from meeting equity criteria that would fairly allocate more 'carbon space' to developing countries, especially LDCs and SIDS, due to their low contribution to historical CO 2 emissions and their right to develop in a safe and sustainable way.
Globally, despite the efforts that will be involved in undertaking these emission reductions included in the LT-LEDS, these are still far from insufficient to put the world on track to reach the 1.5°C goal, while providing enough time and carbon space to the least developed countries.Similar to other published studies (Matthews & Wynes, 2022), the analysis reveals that the current emission reductions still appear to prioritize economic growth rather than embracing the necessary structural changes to achieve the PA mitigation goal.
According to the authors of this study, there is a pressing need to incorporate the principles of equity and of CBDR&RC into the design and implementation of NZE.This analysis, and the research conducted by Lenzi et al., 2021, demonstrate that these principles are not currently being operationalized.

Conclusions
The LT-LEDS have the potential to play a crucial role in realizing the long-term objective of the PA.Achieving a carbon-neutral world necessitates profound structural transformations in energy, transportation, and agriculture sectors, alongside economic production and consumption models, instead of solely prioritizing economic growth.To implement these changes, a comprehensive long-term vision at country level is indispensable, guiding short-term policy decisions, prioritizing a profound structural change.However, the effectiveness of LT-LEDS is significantly undermined by their non-binding nature, the absence of agreed-upon guidelines for their content, and the lack of a monitoring mechanism for their implementation.This can be seen just from observing that from the 194 Parties that ratified the Paris Agreement, only 53 have submitted LT-LEDS, which makes up for just 27% of Parties presenting LT-LEDS and shows how there are still 141 Parties (around 73%) that haven't submitted LT-LEDS.While a significant number of Parties have ratified the Paris Agreement, a much smaller proportion has taken concrete steps towards long-term low-emission strategies, and an even smaller group presented climate-neutral commitments.
The analysis conducted using the Checklist on 53 LT-LEDS reveals significant disparity in the content of these documents, which is to be expected.On average, the Parties studied only report 60% of the items outlined in the Checklist in their LT-LEDS.Many of these Parties outline sector-specific actions but fail to provide measurable targets or mechanisms by sector for monitoring progress.It is also noteworthy that the principle of CBDR&RC is rarely addressed in these LT-LEDS.While a considerable number of LT-LEDS express the country's commitment to the global goals of the PA, it is not always well-defined how each individual LT-LEDS contributes to achieving these goals.There is a lack of clarity on how these countries will implement strategies to achieve their pledges and on what the implications of these roadmaps are for the consumption and distribution of the Remaining Global Carbon Budget.Paradoxically, in general, the LT-LEDS presented by LDCs and SIDS are the ones that provide more comprehensive and detailed information, whereas within the group of developed countries, there is a higher prevalence of LT-LEDS with lower levels of information.
The RGCB compatible with achieving a 1.5°C objective with a 67% likelihood amounts to 400 GtCO 2 .Using this as a threshold amount yields concerning results when assessing progress against NZE targets outlined by 21 Parties in their LT-LEDS.This analysis of net-zero CO 2 commitments reveals that if Parties do not expedite their target year for achieving carbon neutrality, only 21 Parties (including the EU27 as a whole), representing only 37% of the global population and 62% of global emissions, will consume a total of 431 GtCO 2 before reaching their net-zero goals.We are thus significantly offtrack from planning emission pathways that could attain the 1.5°C goal.Additionally, it can be argued that if the remaining majority of the world's population consumed the same accumulated average CO 2 per capita per year as these 21 analysed Parties, global consumption would reach 1164 GtCO 2 .This level of consumption could still align with the RGCB compatible with the PA goal of limiting global warming to well below 2°C (67% likelihood) (IPCC, 2021).It is also worth noting that from the 194 total number of Parties to the PA, only 53 had reported LT-LEDS by 2022, and of these only 35 (this figure includes 14 countries in the EU27) presented NZE targets.
The results obtained from this analysis complement those of the 'Long-term low-emission development strategies.Synthesis report by the secretariat', presented by the UNFCCC in October 2022.The report also indicates that the LT-LEDS are significantly misaligned with the scenarios that are compatible with the 1.5°C objective, but relatively close to those compatible with a global warming of 2°C.While the UNFCCC report evaluates the aggregate effect of the LT-LEDS based on annual GHG emissions and examines the coherence between NDCs with LT-LEDS, it does not consider the implications of LT-LEDS and their goals for the global carbon budget (UNFCCC, 2022c).
It is also concerning to observe that the formulation of NZE targets and commitments by countries completely disregards explicit considerations of equity and the principle of CBDR&RC.Our results reveal that the developed countries analysed here (representing 12% of the world population) will continue consuming a large share of the RGCB (around 35%).Despite bearing greater historical responsibility, they will continue to exhibit higher per capita emissions on average compared to developing countries.On the other hand, the NZE commitments of LDCs and SIDS suggest that they will persist with remarkably low per capita emissions, which may call into question their right to develop.
The PA leaves it up to countries to establish their GHG mitigation commitments according to their national circumstances.However, a significant, unresolved challenge lies in reconciling the bottom-up approach of the Agreement in a world with constrained carbon space and a limited RGCB.Even more daunting is the task of limiting emissions in an equitable manner, considering the vast inequalities and diverse development requirements presented worldwide.Regrettably, the LT-LEDS submitted to date fall far short of addressing any of these challenges.

Disclosure statement
No potential conflict of interest was reported by the author(s).

Table 1 .
List of the Parties that submitted their LT-LEDS to the UNFCCC; group to which they belong (UNCTADstat, 2022); information on the mitigation goal collected from the LT-LEDS; and whether they have presented a net-zero emissions goal.
Net zero emissions 'as soon as viable in the second half of the century'

Table 2 .
Categories and sections contained in the 'Quality Assurance Checklist: For Long-Term Low Greenhouse Gas Emission Development Strategies'.Source (WRI and UNDP, 2021).

Table 3 .
Ratios of each answer per section.Source: Annex B -Analysis LT-LEDS Submitted by September 23rd, 2022.

Table 4 .
Percentage of countries that answered more than 80% of the questions and less of 50% of the questions from the Checklist.Source: 6Column "Total Partially", Annex B, Supplementary Material. .