Karl Scheifinger

Global emissions scenarios describe the nature and pace of future transitions. As such, they have been critical to inform international policy and efforts to limit global warming to specific levels. Since the IPCC Sixth Assessment Report (AR6), the global mitigation landscape has changed substantially, yet many scenario-based benchmarks continue to rely on static assessments. The Scenario Compass Initiative (SCI) responds to this gap by providing a continuously updated, transparent, and curated collection of global emissions scenarios, combined with a systematic benchmarking framework that tracks how mitigation requirements evolve over time.SCI introduces a novel “live” scenario collection approach that enables ongoing submission, vetting, and release of scenarios, ensuring timely access while maintaining quality control. Scenarios are assessed against feasibility and sustainability criteria, allowing the identification of a policy-relevant subset without relying on statistical outlier exclusion. Building on this curated ensemble, SCI derives benchmarks across key mitigation dimensions, including near-term emissions reductions, renewable energy deployment, net-zero timing, and reliance on net-negative emissions.Comparing current benchmarks with those underlying AR6 reveals a marked shift in feasible mitigation pathways. The most ambitious AR6 category—characterized by immediate, steep emissions reductions and minimal temperature overshoot—has effectively become unattainable given observed emissions trends and delayed action. As a result, benchmarks for near-term mitigation, net-zero timing, and carbon dioxide removal have all shifted accordingly. At the same time, while quantitative assumptions span wide numerical ranges, most scenarios continue to rely on a narrow set of underlying socioeconomic narratives aligned with SSP1 and SSP2.This presentation will inform about the updated benchmarks which provide critical reference points for interpreting contemporary scenarios and for supporting robust, policy-relevant climate decision-making.

Long-term global emissions scenarios underpin climate policy by providing quantitative benchmarks for near-term actions consistent with long-term temperature goals. However, scenario benchmarks can quickly become outdated as real-world emissions, policies, technologies and even geopolitics evolve. Here we present an updated and curated ensemble of global integrated assessment model (IAM) scenarios developed since the IPCC Sixth Assessment Report. We use a continuous “live” collection and vetting framework designed for regular updating - with planned annual releases - to derive up-to-date policy-relevant benchmarks. Of more than 1,500 collected scenarios, only a minority remains consistent with recent trends between 2015 and 2025. After assessing feasibility, plausibility, and sustainability, 162 scenarios form the basis for updated benchmarks. These indicate that pathways limiting peak warming to around 1.7 °C above pre-industrial levels represent the lowest warming outcomes currently supported in the recent literature, requiring global greenhouse gas (GHG) emissions reductions of around 60% by 2035 and 90% by 2050 relative to 2019, with net-zero CO₂ emissions reached around 2050. All Paris-consistent benchmarks require a rapid transitioning away from unabated fossil fuels, an unprecedented scale-up of renewable energy, and limited but necessary deployment of carbon dioxide removal (CDR). While limiting peak warming to 1.5 °C with low or no overshoot is no longer feasible, returning warming to 1.5 °C this century (after overshooting to about 1.7 °C) remains possible.

Regional disparities in mitigation capacity and the slow deployment of certain novel technologies pose significant challenges to achieving ambitious climate goals. We explore how accounting for technological and mitigation capacity considerations alters the regional distribution of mitigation efforts, and how these shifts relate to fairness considerations, all while staying within the scenario space aligned with the Paris Agreement’s goal of holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels. To do so, we use a new set of scenarios generated using eight global integrated assessment models (IAMs). These scenarios shift near-term mitigation efforts to regions with greater mitigation capacity by implementing differentiated carbon pricing and emission caps, deviating from the default assumption of a uniform carbon price in global IAMs. We examine the scale of regional emissions reductions and energy system transformations needed, highlighting the implications in the near term. Our findings from the most ambitious scenario, highlight that Organisation for Economic Co-operation and Development (OECD) countries could reduce total CO ₂ emissions as reported in the models by approximately 85% (range: 81%–114%) by 2040 relative to 2020 levels and achieve net-zero CO ₂ emissions around 2045—well beyond the 58% reduction (range: 33%–71%) projected under default 2 °C pathways with a globally uniform carbon price. Similarly, China could reduce CO ₂ emissions by 78% (range: 55%–83%) by 2040 and reach net-zero by 2050, compared to a 50% reduction (range: 47%–72%) in default scenarios. In this ambitious scenario, other regions could aim to reach net-zero CO ₂ by 2070. This redistribution of mitigation efforts involves an accelerated phase-out of fossil fuels—coal, oil, and gas—primarily within the OECD region and, to a certain extent, in China. It also includes an early—but, in line with our feasibility considerations, limited—scale-up of carbon capture and storage capacity, along with significant reductions in final energy demand that go beyond current pledges and ambition levels. Beyond feasibility considerations, the new scenarios assume more mitigation efforts in regions with higher mitigation capacity proxied through institutional capacity, consistent with a capacity-based conception of regional fairness. Integrating certain considerations of feasibility and fairness into scenario assessments enables the development of alternative pathways that are, in some respects, more policy-relevant and help expand the scenario space—thereby responding to some of the recent critiques of global IAMs.

Global mitigation scenarios allocate resources in ways that align with specific climate targets under varying assumptions. These allocations inevitably raise questions of distributional justice. With scenarios becoming a major tool for global climate policy, the distributional implications of global mitigation scenarios are increasingly central to international political debates and negotiations. However, the scenario community lacks tools to systematically and transparently incorporate considerations of distributional justice in scenario development. This research addresses this gap by operationalizing philosophical concepts of distributional justice, referred to as justice patterns.The justice patterns examined in this study include Aggregate Utilitarian (core idea: everyone benefits), Egalitarian (equal outcomes for all), Prioritarian (priority to those worst-off), Sufficientarian (ensuring everyone reaches a minimum threshold), and Limitarian (ensuring no one exceeds a maximum threshold). With two concrete applications we demonstrate that these justice patterns provide a useful framework for integrating distributional justice considerations in scenario development.First, we quantify justice patterns to analyse the distributional logic of energy service access in scenarios from the AR6 database. Our findings reveal that Prioritatrian and Egalitarian patterns are the most prominent in AR6 scenarios, while Sufficientarian and Limitarian patterns remain underexplored, leaving a gap in the scenario space.Second, we introduce an open-source web application that visualizes justice patterns as idealized trajectories, allowing stakeholders to explore and express their preferences for justice patterns in varying contexts. We demonstrate the tool’s potential to guide scenario development in a small pilot study.We conclude by advocating for future scenario studies to systematically incorporate diverse justice patterns to examine potential conflicts between mitigation strategies and justice considerations. Furthermore, we recommend extending assessments beyond energy services to encompass non-material dimensions critical to socially acceptable futures, such as freedom and power. By operationalizing justice patterns, this research establishes a foundation for comprehensive scenario assessments on distributional justice and systematic stakeholder engagement.