Abstract. Parties to the 2015 Paris Agreement agreed to limit the long-term increase in global average temperature to well below 2 °C and pursue efforts to keep temperatures below 1.5 °C relative to pre-industrial levels. As the world is fast approaching the 1.5 °C warming level on a sustained basis, and with 2024 likely the first year that was over 1.5 °C warmer than 1850-1900, there is ever increasing interest in how we will know whether and when 1.5 °C warming since pre-industrial has been reached or exceeded with respect to a long-term average. This paper represents a comprehensive community methodological overview, building on the IPCC 6th assessment. It explains why there is no straightforward answer and proposes clear and reasoned ways forward. Existing challenges are as follows. Firstly, the Paris Agreement text contains definitional ambiguities around 'pre-industrial', 'global average temperature', whether the assessment should be on realised or long-term human-induced warming, and over what time frame the long-term temperature goal applies. Then, there are intrinsic limitations of observational records which get more uncertain further back in time due to data sparsity and measurement heterogeneity. Finally, in a non-stationary climate, multidecadal mean indicators of global temperature change will either lag behind the change or must rely on expected future temperature changes (based on extrapolation, initialized predictions, or scenario-based and constrained projections). Our analysis shows that knowing 'whether we are there yet' is a multifaceted and inherently probabilistic problem that includes information on the definition of a specific level of global warming, temperature changes over multiple timescales, and also potentially includes unpacking the attribution of human-caused changes from observed variations. Given the policy relevance of understanding where the world stands relative to 1.5 °C, or any other level of global warming since pre-industrial, there are a number of practical steps which could be taken to increase specificity in answering this critical question in a timely manner, and inform future monitoring and assessment activities. This paper reviews a broad range of approaches, identifies the most pragmatic, robust and transparent, and clarifies requirements for use in real time including how to handle and represent remaining uncertainties. We show that it is possible by combining lines of evidence and several methodologies to estimate the present long-term warming level without delay in a manner that is robust both in retrospective validation of crossing past warming levels and, critically, to divergent warming futures including potential wildcard impacts of large volcanoes which can mask underlying warming for several years. Results are benchmarked against historical exceedances of 0.5 °C and 1 °C warming. Long-term warming as assessed using the approaches developed herein and data up to and including 2024 stands at 1.40 [1.23–1.58] °C, and underlying human-caused warming stands at 1.34 [1.18–1.50] °C. In IPCC quantified likelihood language this means that it was unlikely that long-term realised warming had exceeded 1.5 °C by the end of 2024 and very unlikely that human-induced warming had exceeded 1.5 °C.

Temporary climate overshoot—especially for 1.5 °C—is now unavoidable. In this Perspective, we show how overshoot emerged in mitigation pathways over the past three decades, from a modelling device for exploring stringent climate goals to an inevitable feature of scenarios. Depending on its extent, overshoot affects the pace and feasibility of emissions reductions, the distribution of socio-economic outcomes, and climate risks in time and space. We show that the magnitude and consequences of overshoot depend not only on biophysical characteristics and model assumptions but equally on scenario design and social and institutional factors. We outline priorities for a new generation of models and scenarios that integrate different climate sciences, supporting robust climate strategies in a world of overshoot. A temporary breach of the temperature target, or overshoot, is unavoidable. The authors review the history of how overshoot evolved in mitigation pathways, the magnitude and outcomes of potential physical and socio-economic impacts, and priorities for future model and scenario development.

Exceeding global warming of 1.5 °C in the near term is now unavoidable. An overshoot pathway, in which exceedance is followed by decline to or below the threshold through net-negative emissions, is now the only remaining route back to 1.5 °C. Permanent exceedance forecloses the recovery from climate impacts that an overshoot pathway may permit, yet even an overshoot pathway leaves lasting legacies. To characterise the reversibility of temporary overshoot impacts, we propose a three-layer analytical framework distinguishing hazards (with four dimensions: magnitude, duration, rate of exceedance, and rate of decline), biophysical responses (reversible vs persistent change), and socioeconomic outcomes (reversible vs irreversible impact). We introduce the socioeconomic commitment threshold, endogenous to the overshoot trajectory: how much overshoot intensity a system can experience before the losses it accumulates persist after temperatures decline, explained by three mechanisms: non-substitutability, threshold-crossing, and lock-in. A typology linking biophysical persistence with socioeconomic irreversibility illustrates how reversible biophysical change can produce irreversible socioeconomic loss, while persistent biophysical change need not produce irreversible outcomes where adaptive capacity is sufficient. Whether temporary exceedance produces permanent harm is determined primarily by socioeconomic rather than biophysical factors, except where permanent biophysical change exceeds adaptation limits. For systems and communities with low adaptive capacity, overshoot concentrates irreversible legacies even where temperatures subsequently decline, placing equity and justice at the centre of overshoot assessment.

As global warming approaches 1.5 °C, the term ‘overshoot’ is becoming increasingly prominent in climate science, policy, and public communication, but the use of this term remains inconsistent and often ambiguous. This article traces the history of the term in ordinary language and science-policy contexts, showing how specialized uses such as ‘temperature overshoot’ or ‘overshoot pathway’ have diverged from the common meaning of exceeding a target or limit. We provide practical guidance for clearer communication, recommending that authors respect the ordinary meaning of overshoot and specify where insights refer to exceedance, peak warming, decline, or return below a given warming level, while avoiding short-hand terminology where it risks misunderstanding.

In a rapidly changing climate, evidence-based decision-making benefits from up-to-date and timely information. We track twelve key sets of indicators of the state of the climate system, closely following Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment report (AR6) methods, to produce our fourth annual publication. One of the indicators, the Earth's energy imbalance (EEI) provides a crucial integrative measure of the overall heating of the planet and the pace of climate change - this has more than doubled since the 1976-1995 period. A newly added indicator of temperature extremes, the number of days experiencing marine heatwaves, has more than tripled between 1991 and 2025.For the 2016-2025 decade average, observed warming relative to 1850-1900 was 1.26 [1.13 to 1.36] degrees C, of which 1.24 [1.0 to 1.5] degrees C was human-induced. Human-induced warming reached 1.37 degrees C relative to 1850-1900 in the year 2025, increasing at a rate of 0.27 [0.2-0.4] degrees C per decade over 2016-2025. This high rate of warming, which matches the all-time high seen last year in the instrumental record, was caused by a combination of greenhouse gas emissions being at an all-time high of 54.6 +/- 5.5 GtCO2e yr-1 over the last decade (2015-2024), as well as reductions in the strength of aerosol cooling. Despite this, there is evidence that CO2 emission growth is slowing. The continuation of these annual updates could track decreases or increases in the rate of human influence and climatic changes presented here, reflecting the outcomes of societal choices during the critical 2020s decade.The data presented herein can provide a useful reference point for the drafting of the IPCC seventh assessment report. In total, we employ analysis from over 40 global datasets (10.5281/zenodo.20499280, Smith et al., 2026a). Future monitoring of these indicators, such as ocean and satellite measurements of the Earth's energy imbalance, are threatened by geopolitical and public funding decisions. Our ability to consistently track many of the indicators requires the continuity of observation programs and coordination mechanisms, including the Global Climate Observing System (GCOS) program, that enable their effective integration and use.

In a rapidly changing climate, evidence-based decision-making benefits from up-to-date and timely information. Here we compile monitoring datasets (published at https://doi.org/10.5281/zenodo.15639576; Smith et al., 2025a) to produce updated estimates for key indicators of the state of the climate system: net emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, the Earth's energy imbalance, surface temperature changes, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes. This year, we additionally include indicators for sea-level rise and land precipitation change. We follow methods as closely as possible to those used in the IPCC Sixth Assessment Report (AR6) Working Group One report. The indicators show that human activities are increasing the Earth's energy imbalance and driving faster sea-level rise compared to the AR6 assessment. For the 2015–2024 decade average, observed warming relative to 1850–1900 was 1.24 [1.11 to 1.35] °C, of which 1.22 [1.0 to 1.5] °C was human-induced. The 2024-observed best estimate of global surface temperature (1.52 °C) is well above the best estimate of human-caused warming (1.36 °C). However, the 2024 observed warming can still be regarded as a typical year, considering the human-induced warming level and the state of internal variability associated with the phase of El Niño and Atlantic variability. Human-induced warming has been increasing at a rate that is unprecedented in the instrumental record, reaching 0.27 [0.2–0.4] °C per decade over 2015–2024. This high rate of warming is caused by a combination of greenhouse gas emissions being at an all-time high of 53.6±5.2 Gt CO2e yr−1 over the last decade (2014–2023), as well as reductions in the strength of aerosol cooling. Despite this, there is evidence that the rate of increase in CO2 emissions over the last decade has slowed compared to the 2000s, and depending on societal choices, a continued series of these annual updates over the critical 2020s decade could track decreases or increases in the rate of the climatic changes presented here.

With increasing frequency and severity of climate risks, communities must further adopt Climate Risk Management (CRM) strategies. As a key component, Climate Risk Assessments (CRA) identify and evaluate climate risks across hazards, areas and sectors. Various CRA frameworks have been proposed and implemented by research, policy and practice. One key gap identified is the effective integration of quantitative and qualitative aspects in CRA to develop comprehensive results as well as ensure integration of various perspectives. For this, it is necessary to understand how quantitative and qualitative risk aspects come together in combined approaches to support and balance each other.In the context of the EU Horizon 2021 project CLIMAAX, we developed a comprehensive CRA framework adapted for the European regional and community level. The Framework unites approaches for risk quantification (provided in the CLIMAAX Handbook) and at the same time encourages qualitative risk input through participation of experts, stakeholders and vulnerable groups. Our approach seeks to respond to needs, recent advancements and best practices in the CRA field by integrating insights from European National Adaptation Plans and Strategies, peer-reviewed literature, as well as existing CRA frameworks and international standards. The framework was collaboratively developed with five European pilot regions and considers survey responses from the CLIMAAX Community of Practice to ensure feasibility and applicability while upholding adaptive flexibility.The CRA Framework is operationalized through a five-step assessment cycle (Scoping, Risk Exploration, Risk Analysis, Key Risk Assessment, Monitoring & Evaluation). These steps are supported by principles of social justice and equity, participatory processes, and technical considerations such as future scenarios. In the quantitative Risk Analysis step the Framework is strongly supported by multiple risk workflows estimating climate risk. The other four steps provide entry points for qualitative risk assessment perspectives, thus requiring translation and interdisciplinary thinking. We innovatively contextualise the risk analysis outcome as quantitative and qualitative aspects are processed together. Through an indicator-based evaluation of risk severity, risk urgency and resilience capacity we consider Key Risks in a multi-hazard risk context.By collecting data from users within the CLIMAAX project, we will assess how qualitative as well as semi-quantitative risk perspectives can benefit and complement quantitative risk estimations as applied in the risk workflows. Further, by effectively integrating diverse perspectives, the framework aims to bridge the translation gap between risk assessment and CRM practices towards fostering resilience.

The Intergovernmental Panel on Climate Change (IPCC) regularly assesses a wide range of research results related to climate change reaching from physical sciences to economic and social sciences to provide policy makers with options for combatting the challenges of climate change. The IPCC authors analyze data across multiple domains and from multiple sources.The IPCC data guidelines enhance the transparency of IPCC outcomes by ensuring that figure creation is traceable, citing input data and long-term preserving data and software. The related data and metadata requested from the authors includes detailed information on datasets used in every figure, for which standardized machine-accessible and -readable information needs to be supported by the input data providers.An example of an important input data provider is the Coupled Model Intercomparison Project (CMIP), which has continuously improved its standards and data infrastructure to keep track with the significant increase in the scale of the project over recent phases. CMIP defines a set of standards including vocabularies for controlled metadata fields, e.g. variable and experiment names, along with the data itself and its structure. A set of infrastructure services provide access to data, through the Earth System Grid Federation (ESGF), description of the climate models used and known errata, through ES-DOC services, and data citation information including data usage in derivative data sets and published papers where known. The contribution will discuss the diverse data-workflows of the IPCC authors and the ways that the CMIP infrastructure supports them. Authors access data from the primary data portals of the ESGF, but also from secondary data portals (Copernicus, Pangeo, Climate4Impact) or local data pools hosted by national institutions. The IPCC authors have faced a number of challenges, including accessing data citation and model description information together with the data, and in identifying new dataset versions with significant changes. With the IPCC’s plan to utilize provenance records in AR7 to gather all information requested by the IPCC data guidelines, machine-readable information accessible through the file headers becomes essential. The entire IPCC AR7 data workflow needs to be supported by tools: the figure creation by the IPCC authors, the report editing process by the TSU and the curation of the CMIP7 input data subset used and the intermediate and final datasets created by various DDC Partners, including bi-directional references between outputs. Virtual workspaces such as CEDA and DKRZ provided for the authors in AR6, which give access to their data pools and common software packages like the ESMValtool, can support the authors in the preparation of their figures and the provision of the requested documentation and provenance information. A dedicated Figure Manager will play a central role in managing the report figures and supporting the overall data workflow. Ultimately, lowering the burden for the authors, the TSU staff and the DDC Partners. This timely gathered information can then be analyzed and used for a harmonization of dataset version usage across the chapters and reports.

With climate change increasingly affecting people, assets and the environment, Climate Risk Assessments (CRA) are seeing strong attention for understanding the scope and scale of climate risks in order to plan and implement adaptation and climate risk management responses. In the context of the EU Horizon 2020 project CLIMAAX we developed an inclusive and harmonized CRA framework adapted for NUTS-1 and NUTS-2 level. This framework aligns with state-of-the-art methodologies and is further complemented by a user-friendly toolbox tailored for risk quantification across European regions. Our approach integrates insights from UCPM documents, European National Adaptation Plans and Strategies, peer-reviewed literature as well as existing CRA frameworks and international standards to respond to needs, recent advancements and best practices in the CRA field. The framework was collaboratively developed with five European pilot regions to ensure feasibility and applicability while pursuing adaptive flexibility. The practical need of the CRA framework led to a five-step assessment cycle (with special emphasis on key risk assessment as a novelty), underpinned by a conceptual context addressing principles, technical choices (e.g. future scenarios) and participatory processes. The framework allows for toolbox extension (the risk analysis) as well as indicates entry points for Climate Risk Management and Adaptation options thereby creating a feedback loop within the CRA cycle. To address compound and multi-hazards aspects of risk, the framework is designed to tackle complexity by referring to a variety of options such as workflows for climate risk quantification or qualitative options together with participatory processes and stakeholder inclusion. The developed CRA framework brings together practical needs and scientific, standardized knowledge. However, further insights are needed to efficiently connect climate risk estimations with climate risk management and adaptation strategies to support communities and regions in their efforts towards building climate resilience.

Limited progress with mitigation makes it almost inevitable that global warming of 1.5°C will be exceeded. This realization confronts Parties to the United Nations Framework Convention on Climate Change (UNFCCC) with a choice either to stabilize warming above but as close as possible to 1.5°C or to reverse global warming back to this level. We review core concepts and current knowledge relating to overshoot: an exceedance and subsequent decline back below a specified global warming level. We clarify the concept and origins of overshoot in science and climate policy, discuss the key drivers of climate-related risks and how they might evolve under overshoot trajectories to foster more systematic research into those risks, and consider the role of adaptation. We then consider the feasibility of overshoot in terms of mitigation across the six feasibility dimensions introduced by the Intergovernmental Panel on Climate Change (IPCC) in its sixth Assessment Report. We conclude by discussing critical barriers, challenges, and knowledge gaps related to overshoot.

As climate change impacts intensify worldwide, assessing climate risks comprehensively is essential for guiding effective disaster risk management and adaptation strategies. This systematic literature review examines the latest developments in Climate Risk Assessment (CRA), focusing on how climate risks are framed and assessed. It explores advancements, ongoing challenges, and emerging opportunities to guide future generations of CRAs. Key findings highlight a more nuanced risk framework that incorporates climate responses, modulating the three risk determinants (exposure, vulnerability, and hazards), as outlined in the latest IPCC assessment. The state-of-the-art concentrates on the temporal and spatial characteristics of hazards, while exposure and vulnerability are increasingly understood as dynamic concepts influenced by socioeconomic changes. Recent developments, such as multi-hazard approaches, risk tolerance integration, and the concept of Climatic Impact-Drivers (CID), provide new perspectives on assessing climate risks. However, managing complexity and uncertainty remain the main operational challenges, underscoring the need for improved CRA methodologies and models, as well as consistent, interoperable datasets. The paper discusses avenues to advance CRA, emphasizing the importance of bridging the gap between academic advancements and practical implementation. Conceptual recommendations include adopting a systemic approach to, for example, better account for the cascading and compounding risks, hazard thresholds, adaptation limits, and risk amplifiers, as well as using storylines to improve CRA communication. Technical recommendations include leveraging emerging technologies such as artificial intelligence, machine learning methods and big data analytics to improve real-time risk prediction and modeling. To enhance the CRA practice, the study advocates for greater stakeholder involvement and inclusive governance to ensure that CRAs remain context-specific and relevant. These recommendations, together with strengthened interdisciplinary collaboration and knowledge-sharing, are expected to pave the way for more effective climate risk management, adaptation, and resilience-building strategies.

Every five to seven years, the Intergovernmental Panel on Climate Change (IPCC) convenes the climate science community to assess the latest knowledge on climate change relevant to policy-makers. This generally takes the form of Assessment Reports (AR) covering the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation. With each cycle, these reports have grown in scope, length, number of referenced papers, and underpinning datasets. During the sixth assessment cycle, a large-scale collective effort went into archiving digital products assessed and generated through the IPCC process. The main objectives driving this initiative are making IPCC’s work more transparent, improving the reproducibility and reusability of the assessment outcomes, better utilization of the services of the IPCC Data Distribution Centre (DDC), and, more generally, compliance with best practices in open science. This paper expands on the motivations for the curation and preservation of digital objects in the IPCC. It gives an overview of how FAIR (Findable, Accessible, Interoperable, Reusable) and open data principles have been implemented in practice and explores some of the successes and setbacks of the AR6 experience. It concludes with recommendations for consolidation and expansion of the approach for AR7. These include a tighter integration of digital curation activities in the IPCC timeline and workflows, better support of IPCC authors and contributors through early training and use of suitable software, improved standardization and harmonization of data and software handling across Working Groups (WGs), and close collaboration with key external data providers and research organizations.

The Sixth Assessment Report (AR6) marked the first time that the Intergovernmental Panel on Climate Change (IPCC) recommended and implemented FAIR data principles as part of the assessment process. While the critical importance and utility of FAIR principles are widely acknowledged, their implementation is not straightforward, especially in this unique context that involves the collaboration of hundreds of scientists around the world from different disciplines, utilising diverse information sources. We describe challenges and lessons learned when sharing data and other digital resources in the context of assessing the physical science basis (Working Group I, WGI). With the primary scope of ensuring transparency and reproducibility, and providing due credit to the data creators who collaborated on the report, authors were guided and supported to encourage the public availability of the data and the associated code used in post-processing. As part of this initiative, data and code for over 200 figures have been made accessible as well as all plotted data for the Summary for Policymakers. Additionally, the assessment foundation datasets, such as climate model simulations, have been curated, along with a novel category of data — datasets constrained through expert assessment (e.g., model-based projections of global surface temperature). Moreover, an innovative digital product was produced to support and expand the assessment done in the WGI AR6, building on these datasets and synthesising key findings for Climatic Impact Drivers: the Interactive Atlas. Its formal inclusion as part of the report was possible thanks to the implementation of FAIR principles, fully compliant to best data practices. Despite successes, challenges emerged with the novel FAIR implementation because of learning by doing and real-time development, managing diverse data, requiring the introduction of new roles and workflows. For authors, adapting dataset structures to fit repository constraints and addressing metadata requirements posed difficulties, as they didn't always align with actual dataset usage or user needs. Simultaneously, repositories faced challenges adapting dataset structures to their systems, ensuring adherence to standard conventions, managing references, reviewing licences, and awaiting author feedback. In this complex landscape, the role of data curators was crucial, serving as a facilitating bridge for information and requirements exchange, providing essential support to authors and collaborating with repositories to seek solutions that effectively integrated the needs of both parties. Flexibility and simplicity proved key allies in overcoming challenges. Prioritising clarity and acknowledging the limitations of a rigid structure enabled smooth navigation of obstacles, resulting in practical and useful outcomes. The new IPCC cycle starts now. FAIR principles need to be fully integrated into the climate assessment process to adhere to the highest standards in data access and stewardship. Our recommendations include the need to integrate data management workflows and engaging authors from the outset, highlighting the significance of data-related tasks for transparency, and enhancing the tools available to support authors. Providing authors clear instructions and timelines is crucial, along with technical assistance from data science experts. Actively endorsement and support of these initiatives by the IPCC leadership is vital for their effective integration into the assessment process.

Scenarios have been an important integrating element in the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) in the understanding of possible climate outcomes, impacts and risks, and mitigation futures. Integration supports a consistent, coherent assessment, new insights and the opportunity to address policy-relevant questions that would not be possible otherwise, for example, which impacts are unavoidable, which are reversible, what is a consistent remaining carbon budget to keep temperatures below a level and what would be a consistent route of action to achieve that goal. The AR6 builds on community frameworks that are developed to support a coherent use of scenarios across the assessment, yet their use in the assessment and the related timelines presented coordination challenges. From lessons within each Working Group (WG) assessment and the cross-WG experience, we present insights into the role of scenarios in future assessments, including the enhanced integration of impacts into scenarios, near-term information and community coordination efforts. Recommendations and opportunities are discussed for how scenarios can support strengthened consistency and policy relevance in the next IPCC assessment cycle.

In every Intergovernmental Panel on Climate Change (IPCC) Assessment cycle, a multitude of scenarios are assessed, with different scope and emphasis throughout the various Working Group reports and special reports, as well as their respective chapters. Within the reports, the ambition is to integrate knowledge on possible climate futures across the Working Groups and scientific research domains based on a small set of “framing pathways” such as the so-called representative concentration pathways (RCPs) in the Fifth IPCC Assessment Report (AR5) and the shared socioeconomic pathway (SSP) scenarios in the Sixth Assessment Report (AR6). This perspective, initiated by discussions at the IPCC Bangkok workshop in April 2023 on the “Use of Scenarios in AR6 and Subsequent Assessments”, is intended to serve as one of the community contributions to highlight the needs for the next generation of framing pathways that is being advanced under the Coupled Model Intercomparison Project (CMIP) umbrella, which will influence or even predicate the IPCC AR7 consideration of framing pathways. Here we suggest several policy research objectives that such a set of framing pathways should ideally fulfil, including mitigation needs for meeting the Paris Agreement objectives, the risks associated with carbon removal strategies, the consequences of delay in enacting that mitigation, guidance for adaptation needs, loss and damage, and for achieving mitigation in the wider context of societal development goals. Based on this context, we suggest that the next generation of climate scenarios for Earth system models should evolve towards representative emission pathways (REPs) and suggest key categories for such pathways. These framing pathways should address the most critical mitigation policy and adaptation plans that need to be implemented over the next 10 years. In our view, the most important categories are those relevant in the context of the Paris Agreement long-term goal, specifically an immediate action (low overshoot) 1.5 °C pathway and a delayed action (high overshoot) 1.5 °C pathway. Two other key categories are a pathway category approximately in line with current (as expressed by 2023) near- and long-term policy objectives, as well as a higher-emission category that is approximately in line with “current policies” (as expressed by 2023). We also argue for the scientific and policy relevance in exploring two “worlds that could have been”. One of these categories has high-emission trajectories well above what is implied by current policies and the other has very-low-emission trajectories which assume that global mitigation action in line with limiting warming to 1.5 °C without overshoot had begun in 2015. Finally, we note that the timely provision of new scientific information on pathways is critical to inform the development and implementation of climate policy. Under the Paris Agreement, for the second global stocktake, which will occur in 2028, and to inform subsequent development of nationally determined contributions (NDCs) up to 2040, scientific inputs are required by 2027. These needs should be carefully considered in the development timeline of community modelling activities, including those under CMIP7.

Intergovernmental Panel on Climate Change (IPCC) assessments are the trusted source of scientific evidence for climate negotiations taking place under the United Nations Framework Convention on Climate Change (UNFCCC). Evidence-based decision-making needs to be informed by up-to-date and timely information on key indicators of the state of the climate system and of the human influence on the global climate system. However, successive IPCC reports are published at intervals of 5–10 years, creating potential for an information gap between report cycles. We follow methods as close as possible to those used in the IPCC Sixth Assessment Report (AR6) Working Group One (WGI) report. We compile monitoring datasets to produce estimates for key climate indicators related to forcing of the climate system: emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, the Earth's energy imbalance, surface temperature changes, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes. The purpose of this effort, grounded in an open-data, open-science approach, is to make annually updated reliable global climate indicators available in the public domain (https://doi.org/10.5281/zenodo.11388387, Smith et al., 2024a). As they are traceable to IPCC report methods, they can be trusted by all parties involved in UNFCCC negotiations and help convey wider understanding of the latest knowledge of the climate system and its direction of travel. The indicators show that, for the 2014–2023 decade average, observed warming was 1.19 [1.06 to 1.30] °C, of which 1.19 [1.0 to 1.4] °C was human-induced. For the single-year average, human-induced warming reached 1.31 [1.1 to 1.7] °C in 2023 relative to 1850–1900. The best estimate is below the 2023-observed warming record of 1.43 [1.32 to 1.53] °C, indicating a substantial contribution of internal variability in the 2023 record. Human-induced warming has been increasing at a rate that is unprecedented in the instrumental record, reaching 0.26 [0.2–0.4] °C per decade over 2014–2023. This high rate of warming is caused by a combination of net greenhouse gas emissions being at a persistent high of 53±5.4 Gt CO2e yr−1 over the last decade, as well as reductions in the strength of aerosol cooling. Despite this, there is evidence that the rate of increase in CO2 emissions over the last decade has slowed compared to the 2000s, and depending on societal choices, a continued series of these annual updates over the critical 2020s decade could track a change of direction for some of the indicators presented here.

<p>A new paradigm for Intergovernmental Panel on Climate Change (IPCC) Working Group I (WGI) data publication has been implemented.  IPCC Data Distribution Centre (DDC) partners at the Centre for Environmental Data Analysis (CEDA), the German Climate Computing Centre (DKRZ) and the Spanish Research Council (CSIC) have worked with the IPCC Technical Support Unit (TSU) for WGI to publish figure data from the Sixth Assessment Report (AR6). The work was guided by the IPCC Task Group on Data Support for Climate Change Assessments (TG-Data) recommendations for Open Science and FAIR data (making data Findable, Accessible, Interoperable, and Reusable) with a general aim to enhance the transparency and accessibility of AR6 outcomes.  We highlight the achievement of implementing FAIR for AR6 figure data and discuss the lessons learned on the road to FAIRness in the unique context of the IPCC.</p> <ul> <li aria-level="1"><strong>F</strong>indable - The CEDA catalogue record for each figure dataset enhances findability. Keywords can be easily searched. Records are organised into collections for each AR6 chapter. There is a two-way link between the catalogue record and the figure on the AR6 website. CEDA catalogue records are duplicated on the IPCC-DDC. </li> <li aria-level="1"><strong>A</strong>ccessible - Scientific language is understandable, acronyms and specific terminology are fully explained. CEDA services provide tools to access and download the data. </li> <li aria-level="1"><strong>I</strong>nteroperable - Where possible data variables follow standard file format conventions such as CF-netCDF and have standard names, where this is not feasible readme files describe the file structure and content. </li> <li aria-level="1"><strong>R</strong>eusable - The data can be reused, shared and adapted elsewhere, with credit, under a Creative Commons Attribution 4.0 licence (CC BY 4.0). Catalogue records link to relevant documentation such as the Digital Object Identifier (DOI) for the code and other supplementary information. The code used to create the figures allows users to reproduce the figures from the report independently. </li> </ul> <p>CEDA catalogue records provide a platform to acknowledge the specific work of IPCC authors and dataset creators whose work supports the scientific basis of AR6. </p> <p>Catalogue records for figure datasets were created at CEDA with data archived in the CEDA repository and the corresponding code stored on GitHub and referenced via Zenodo.  For instances where the data and code were blended in a processing chain that could not be easily separated, we developed criteria to categorise the different blends of data and code and created a decision tree to decide how best to archive them. Key intermediate datasets were also archived at CEDA.</p> <p>Careful definition of metadata requirements at the beginning of the archival process is important for handling the diversity of IPCC figure data which includes data derived from climate model simulations, historical observations and other sources of climate information. The reality of the implementation meant that processes for gathering data and information from authors were specified later in the preparation of AR6. This presented challenges with data management workflows and the separation of figure datasets from the intermediate data and code that generated them. </p> <p>We present recommendations for AR7 and scaling up this work in a feasible way.</p>