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Despite faster-than-expected progress in clean energy technology deployment, global annual CO2 emissions have increased from 2020 to 2023. The feasibility of limiting warming to 1.5 °C is therefore questioned. Here we present a model intercomparison study that accounts for emissions trends until 2023 and compares cost-effective scenarios to alternative scenarios with institutional, geophysical and technological feasibility constraints and enablers informed by previous literature. Our results show that the most ambitious mitigation trajectories with updated climate information still manage to limit peak warming to below 1.6 °C (‘low overshoot’) with around 50% likelihood. However, feasibility constraints, especially in the institutional dimension, decrease this maximum likelihood considerably to 5–45%. Accelerated energy demand transformation can reduce costs for staying below 2 °C but have only a limited impact on further increasing the likelihood of limiting warming to 1.6 °C. Our study helps to establish a new benchmark of mitigation scenarios that goes beyond the dominant cost-effective scenario design.

Rising affluence and a warming climate mean that the demand for air conditioning (AC) is rising rapidly, as society adapts to climate extremes. Here we present findings from a new methodological framework to flexibly couple and emulate these growing demands into a global integrated assessment model (IAM), subsequently representing the positive feedbacks between rising temperatures, growth in cooling demand, and carbon emissions. In assessing global and regional climate change impacts on cooling energy demand, the emulator incorporates climate model uncertainties and can explore behavioural and adaptation-related assumptions on setpoint temperature and access to cooling. It is also agnostic to the emissions and climate warming trajectory, enabling the IAM to run new policy-relevant scenarios (Current Policies, 2 and 1.5 °C) with climate impacts that do not follow Representative Concentration Pathways (RCPs). We find that climate model uncertainty has a significant effect, more than doubling the increase in electricity demand, when comparing the 95th percentile cases to the median of the climate model ensemble. Residential AC cooling energy demands are expected to increase by 150% by 2050 whilst providing universal access to AC would result in the order of a 400% increase. Depending on the region, under current policies and limited mitigation, climate change could bring in the order of 10-20% higher cooling-related electricity demands by 2050, and approximately 50% by 2100. Set point temperature has an important moderating role - increasing internal set-point from 23 to 26 °C, approximately halves the growth in electricity demand, for the majority of scenarios and regions. This effect is so strong that the change in set point temperature to both residential and commercial sectors outweighs the growth in demand that would occur by providing universal access to AC by 2050 to the 40% of the global population who would otherwise not afford it.

The building sector in China is responsible for 40% of total energy-related CO2 emissions, driven by its large population, continuous economic growth, and construction boom. In addition to greenhouse gas (GHG) emissions from energy use, buildings drive significant emissions for construction activities and production of energy-intensive materials, such as steel and cement. While supply-side energy strategies have been extensively explored, a demand-side perspective that considers stock dynamics and circularity improvements is essential to assess sustainable pathways for the buildings sector. Here, we explore a set of decarbonization scenarios for the building sector in China considering a range of circular strategies and their interplay with different climate policies. The strategies include lifetime extension of buildings, switch to wood-based construction, reduction of per-capita floorspace, and a combination of all three strategies. We use the building sector model MESSAGEix-Buildings soft linked to the integrated assessment model (IAM) MESSAGEix-GLOBIOM and prospective life cycle assessment (LCA) to assess the effects of these circular strategies on building material and energy demands, and operational and embodied emissions. We find that the three strategies could reduce building material demand up to 60% on mass basis by 2060 compared to a reference scenario with continuation of current policies. This translates into a reduction of embodied and total GHG emissions of 62% and 24%, respectively, significantly contributing to achieving decarbonization targets. Integrating industrial ecology methods in IAMs, as demonstrated in this study, can provide valuable insights to inform national policy decisions on mitigation strategies accounting for both demand and supply sides.

The chances of a global hydrogen economy becoming a reality have increased significantly since the COVID pandemic and the war in Ukraine, and for net zero carbon emissions. However, intercontinental hydrogen transport is still a major issue. This study suggests transporting hydrogen as a gas at atmospheric pressure in balloons using the natural flow of wind to carry the balloon to its destination. We investigate the average wind speeds, atmospheric pressure, and temperature at different altitudes for this purpose. The ideal altitudes to transport hydrogen with balloons are 10 km or lower, and hydrogen pressures in the balloon vary from 0.25 to 1 bar. Transporting hydrogen from North America to Europe at a maximum 4 km altitude would take around 4.8 days on average. Hydrogen balloon transportation cost is estimated at 0.08 USD/kg of hydrogen, which is around 12 times smaller than the cost of transporting liquified hydrogen from the USA to Europe. Due to its reduced energy consumption and capital cost, in some locations, hydrogen balloon transportation might be a viable option for shipping hydrogen compared to liquefied hydrogen and other transport technologies.

The authors are all devoted energy system and sustainability transformation scholars, who collaborate regularly and actively at global and local levels to advance the knowledge space of demand-side solutions and policies. They are members of a growing bottom-up initiative, the Energy Demand Changes Induced by Technological and Social Innovations (EDITS) network (https://iiasa.ac.at/projects/edits), which builds on various research disciplines to facilitate advances in modeling, data compilation, and analysis of the scope and breadth of the potential contributions of demand-side solutions for climate change mitigation, improved wellbeing for all, and sustainability, complementing supply-side solutions for decarbonizing the energy and material systems.

In recent years, discussions surrounding climate change have increasingly emphasized the significance of demand-side solutions. This shift has led to an interdisciplinary and bottom-up approach aimed at supporting global efforts to mitigate climate change. However, conventional modelling tools used to understand the energy demand system and to inform policymaking often fall short in capturing bottom-up dynamics accurately and at the required level of granularity. This is particularly evident in the nuanced and complex aspects of behavioural and social changes and their interactions. This research introduces a novel coupled -agent-based and integrated assessment modelling framework designed to analyse the advantages arising from diversity in renovation decisions, social dynamics, and the evolution of residential building stocks. This study demonstrates that, to effectively formulate realistic policies leading to substantial changes in building energy demand, policymakers require decision-support tools that extend beyond the confines of the rationality principle.

The global shift toward a sustainable and eco-friendly energy landscape necessitates the adoption of long-term, high-capacity energy storage solutions. This research introduces an inventive energy storage concept involving the movement of granular materials from a lower elevation to a higher point within natural terrains such as mountains or excavated mining sites. Electrical energy is employed to charge electric batteries that elevate the granular material, thereby storing potential energy. Subsequently, this material is transported down during the electricity generation phase, and the regenerative braking mechanism converts the gravitational energy to replenish the vehicle's battery. The stored energy within these vehicles is then dispatched during peak demand periods or utilized by the vehicles for other freight transportation purposes. Our findings demonstrate a power cost of 1200 USD/kW, an energy storage expense spanning from 1 to 10 USD/kWh, a levelized cost of storage ranging from 35 to 200 USD/MWh, and a global annual potential of approximately 5.4 PWh. Electric vehicle gravity energy storage showcases its capability to bolster sustainable development by offering seasonal and multi-year energy storage services.

The International Institute for Applied Systems Analysis (IIASA), in collaboration with its Japan National Member Organization (NMO), supported by Ministry of the Environment Japan (MOEJ) has initiated a joint research endeavor centered on Cities Transformation. The primary aim of this collaborative effort's inaugural phase is the compilation of a fast-track comprehensive report. This report aims to consolidate the current understanding of urban transformations, identifying critical knowledge gaps therein. It serves to support the scientific community, city stakeholders, and policy-makers in discerning areas warranting greater attention and, crucially, further investigation and study. Particularly, it provides updates on the IPCC 7th Assessment Cycle, with a specific focus on its Special Report on Climate Change and Cities. Commencing with an overview of global urbanization trends, the report delves into the status of informal urban settlement development (Section 2). Subsequently, it comprehensively discusses the physical aspects of climate change, including impacts, vulnerability, adaptation, and mitigation, with a spotlight on air pollution and waste challenges (Section 3). Section 4 shifts focus to systems transformation, examining sectors and cross-cutting perspectives through various case studies. Following this, Section 5 investigates the enabling conditions for city transformations, emphasizing the roles of governance, behavioral and lifestyle changes, innovation and technology, and finance. Expanding further, Section 6 assesses the synergies and trade-offs of mitigation and adaptation strategies, with a particular lens on Sustainable Development Goals (SDGs), health, and well-being. The report concludes by recognizing significant knowledge gaps highlighted through expert insights.

The construction materials used in buildings have large and growing implications for global material flows and emissions. Material Intensity (MI) is a metric that measures the mass of construction materials per unit of a building's floor area. MIs are used to model buildings' materials and assess their resource use and environmental performance, critical to global climate commitments. However, MI data availability and quality are inconsistent, incomparable, and limited, especially for regions in the Global South. To address these challenges, we present the Regional Assessment of buildings' Material Intensities (RASMI), a new dataset and accompanying method of comprehensive and consistent representative MI value ranges that embody the variability inherent in buildings. RASMI consists of 3072 MI ranges for 8 construction materials in 12 building structure and function types across 32 regions covering the entire world. The dataset is reproducible, traceable, and updatable, using synthetic data when required. It can be used for estimating historical and future material flows and emissions, assessing demolition waste and at-risk stocks, and evaluating urban mining potentials.

Energy system and computable general equilibrium (CGE) models play vital roles in climate change mitigation studies. These models have advantages and disadvantages, and attempts have been made to integrate them. This study aimed to describe the method for integrating energy system and CGE models and demonstrate the new model that captures the strengths of both models. The method developed in this study ensured the detailed convergence of the energy system by exchanging the results iteratively. We demonstrated the model integration by adopting the method to MESSAGEix-GLOBIOM and AIM/Hub and estimating a mitigation scenario that limits the temperature rise to below 2 °C under the middle-of-the-road socioeconomic projection in Shared Socioeconomic Pathways. As a result of the integration, the index showing the difference between the two models proposed in this study decreased from 1.0 to 0.066. Therefore, we confirmed that these models estimated consistent scenarios. The diagnostic indicators showed that compared to its counterpart CGE model, the newly-developed model was characterized by a higher contribution of demand-side reductions, a lesser alteration in the primary energy supply composition, and lower abatement costs. Given the convergence and advantages of the integrated framework, the proposed method is useful for further application to mitigation studies.

IPCC reports, to date, have not featured ambitious mitigation scenarios with degrowth in high-income regions. Here, using MESSAGEix-Australia, we create 51 emissions scenarios for Australia with near-term GDP growth going from +3%/year to rapid reductions (−5%/year) to explore how a traditional integrated assessment model (IAM) represents degrowth from an economic starting point, not just energy demand reduction. We find that stagnating GDP per capita reduces the mid-century need for upscaling solar and wind energy by about 40% compared to the SSP2 growth baseline, and limits future material needs for renewables. Still, solar and wind energy in 2030 is more than quadruple that of 2020. Faster reductions in energy demand may entail higher socio-cultural feasibility concerns, depending on the policies involved. Strong reductions in inequality reduce the risk of lowered access to decent living services. We discuss research needs and possible IAM extensions to improve post-growth and degrowth scenario modelling.

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Climate change is an extremely complex challenge characterized by its systemic nature and deep uncertainties. Thus, finding solutions requires a continuing and constructive dialogue between the research community and a wide range of stakeholders from governments, non-governmental organizations, civil society, international organizations, industry, businesses and financial institutions. The ENGAGE project (https://www.engage-climate.org/) is advancing knowledge co-production through an iterative process of stakeholder engagement with two main streams: (i) stakeholder co-design and assessment of global decarbonization pathways and (ii) stakeholder dialogues on national policies and pathways. Both the global and national stakeholder processes are designed to inform multiple project activities, including: conceptualization of feasibility and assessing the feasibility of decarbonization policies and strategies; decarbonization pathway development using integrated assessment models and considering both feasibility and equity; and assessment of the relative importance of climate change impacts vis-Ã -vis potential co-benefits. With the start of the COVID-19 pandemic six months after the beginning of the project, all of the stakeholder engagement activities had to be organized as online events. Between March 2020 and April 2022, 5 online workshops were organized, two at the global level and 3 at the regional/national level. This paper documents how the challenges of effectively engaging stakeholders in a co-design and dialogue process in an online setting have been met through a process of evaluation and learning that led to the introduction of new approaches and tools to support an inclusive exploration and development of low-carbon transition pathways. We show that a combination of interactive visualizations, open channel surveys and moderated breakout groups are particularly useful tools for online stakeholder engagement. The learning that has taken place through the use

Low-carbon energy transitions taking place worldwide are primarily driven by the integration of renewable energy sources such as wind and solar power. These variable renewable energy (VRE) sources require energy storage options to match energy demand reliably at different time scales. This article suggests using a gravitational-based energy storage method by making use of decommissioned underground mines as storage reservoirs, using a vertical shaft and electric motor/generators for lifting and dumping large volumes of sand. The proposed technology, called Underground Gravity Energy Storage (UGES), can discharge electricity by lowering large volumes of sand into an underground mine through the mine shaft. When there is excess electrical energy in the grid, UGES can store electricity by elevating sand from the mine and depositing it in upper storage sites on top of the mine. Unlike battery energy storage, the energy storage medium of UGES is sand, which means the self-discharge rate of the system is zero, enabling ultra-long energy storage times. Furthermore, the use of sand as storage media alleviates any risk for contaminating underground water resources as opposed to an underground pumped hydro storage alternative. UGES offers weekly to pluriannual energy storage cycles with energy storage investment costs of about 1 to 10 USD/kWh. The technology is estimated to have a global energy storage potential of 7 to 70 TWh and can support sustainable development, mainly by providing seasonal energy storage services.

The chances of a global hydrogen economy becoming a reality have increased significantly since the COVID pandemic and the war in Ukraine, and for net zero carbon emissions. However, intercontinental hydrogen transport is still a major issue. This study suggests transporting hydrogen as a gas at atmospheric pressure in balloons using the natural flow of wind to carry the balloon to its destination. We investigate the average wind speeds, atmospheric pressure, and temperature at different altitudes for this purpose. The ideal altitudes to transport hydrogen with balloons are 10 km or lower, and hydrogen pressures in the balloon vary from 0.25 to 1 bar. Transporting hydrogen from North America to Europe at a maximum 4 km altitude would take around 4.8 days on average. Hydrogen balloon transportation cost is estimated at 0.08 USD/kg of hydrogen, which is around 12 times smaller than the cost of transporting liquified hydrogen from the USA to Europe. Due to its reduced energy consumption and capital cost, in some locations, hydrogen balloon transportation might be a viable option for shipping hydrogen compared to liquefied hydrogen and other transport technologies.

Workshops bringing scientists together with stakeholders from various backgrounds have shown the importance of dialogue for co-designing climate pathways and highlighted the need for physical meetings and capacity building. To find and implement solutions to climate change and other complex problems that society faces, requires constructive dialogue between the research community and a wide range of other stakeholders. Since 2019, the ENGAGE project has developed and used a carefully designed stakeholder engagement process to co-design climate mitigation pathways through open discussions about a range of topics using a combination of surveys, visual tools, and presentations.

As the world faces the risks of dangerous climate change, policymakers, industry and civil society leaders are counting on Integrated Assessment Models (IAMs) to inform and guide strategies to deliver on the objectives of the Paris Agreement (PA) and subsequent agreements. The Exploring National and Global Actions to Reduce Greenhouse Gas Emissions (ENGAGE) project has responded to this challenge by engaging these stakeholders in co-producing a new generation of global and national decarbonization pathways.

Embracing the notion of feasibility, this research shows that the world will probably overshoot 1.5°C, largely owing to low institutional capacity. Energy demand reduction and electrification are two options to turn down the heat, and addressing weak institutions is crucial. In the past, climate scenarios have focused on how to curb warming for the lowest economic cost. But cost is only one factor in the overall feasibility of climate mitigation. New research accounts for other dimensions of feasibility, encompassing technology, natural resources, and the capacity of governments to implement mitigation.

Buildings are key in supporting human activities and well-being by providing shelter and other important services to their users. Buildings are, however, also responsible for major energy use and greenhouse gas (GHG) emissions during their life cycle. Improving the quality of services provided by buildings while reaching low energy demand (LED) levels is crucial for climate and sustainability targets. Building sector models have become essential tools for decision support on strategies to reduce energy demand and GHG emissions. Yet current models have significant limitations in their ability to assess the transformations required for LED. We review building sector models ranging from the subnational to the global scale to identify best practices and critical gaps in representing transformations toward LED futures. We focus on three key dimensions of intervention (socio-behavioral, infrastructural, and technological), three megatrends (digitalization, sharing economy, and circular economy), and decent living standards. This review recommends the model developments needed to better assess LED transformations in buildings and support decision-making toward sustainability targets.

The Climate Solutions Explorer website maps and presents information about mitigation pathways, avoided climate impacts, vulnerabilities and risks arising from development and climate change. www.climate-solutions-explorer.eu The Mitigation (and Summary) Dashboards present mitigation information, i.e. emissions, energy and carbon sequestration, for over 200 countries and 10 regions. To present data for all countries, Integrated Assessment Model runs from the MESSAGEix-GLOBIOM model have been downscaled by using a methodology described in Sferra et al. 2021 [1]. The algorithm produces a range of pathways consistent with the underlying IAM-results, based on criteria such as historical data, planned capacities, country-available resource in the form of supply cost-curves, quality of governance as well as regional benchmarks based on IAM results. The data is provided from 2020 to 2070, for a limited set of variables used on the website. The scenarios included are: Current Policies: Current Policies scenarios here are based on the implementation of national mitigation targets implemented by country without any further strengthening of action. Expected to lead to 2.7 °C by 2100. The data is from the MESSAGEix-GLOBIOM_1.1 GP_CurPol_T45 scenario. NDCs Delayed Action to 2030: Assumes trajectory based on the implemented NDCs until 2030, and then reduces emissions typically in line with a globally 2°C by 2100. The data is from the MESSAGEix-GLOBIOM_1.1 GP_NDC2030_T45 scenario. Glasgow Pledges: "Glasgow Pledges" scenarios here are based on the pledges made by countries at the 2022 COP26 Glasgow Summit, and represent increased ambition, likely taking the world closer to below 2°C in 2100, but still some distance away from the aspirations of 1.5°C of the Paris Agreement. The data is from the MESSAGEix-GLOBIOM_1.1 GP_Glasgow scenario. Glasgow Pledges+: "Glasgow Pledges+" scenarios drops the NDC pledges and expands mid-century strategy pledges to net-zero for all countries and regi

Developing transformative pathways for industry’s compliance with international climate targets requires model-based insights on how supply- and demand-side measures affect industry, material cycles, global supply chains, socio-economic activities and service provisioning supporting societal wellbeing. Herein, we review the recent literature modelling the industrial system for Low Energy and Materials Demand (LEMD) futures, resulting in lowered environmental pressures without relying on negative emissions. We identify 77 innovative studies drawing on nine distinct industry modelling traditions and critically assess system definitions and scopes, biophysical and thermodynamic consistency, granularity and heterogeneity, and operationalization of demand and service provision. We find large potentials of combined supply- and demand-side measures to reduce current economy-wide material use by -56%, energy use by -40 to -60%, and GHG emissions by -70% to net-zero. We call for strengthening interdisciplinary collaborations between industry modelling traditions and demand-side research, to produce more insightful scenarios and discuss research challenges and recommendations.

Global Integrated Assessment Models (IAMs) used to characterise mitigation pathways have very limited or no formal representation of lifestyles and lifestyle change. We demonstrate a novel approach to endogenously simulating low-carbon lifestyle heterogeneity and lifestyle change through soft-coupling with our new empirically-based LIFE model. Coupling LIFE to global IAMs enables dynamic simulation of distinctive lifestyle change contributions to targeted mitigation strategies. We set out the empirical basis of the LIFE model, the methodological steps for soft-coupling to a global IAM, and show results from a test application to the residential sector using the MESSAGEix-Buildings model. A first key insight is that coupling with the LIFE model introduces heterogeneous behaviour between 'engaged' types, who experience faster and higher reductions in final energy demand compared to 'disengaged' types. When we further simulate a widespread shift in normative values, this gap is closed. A second key insight is that drivers of lifestyle change, act differently across 'Improve' and 'Avoid' dimensions. The 'disengaged' types, characterised by lower incomes, are more highly responsive to energy saving 'Avoid' behaviours. Our approach demonstrates how improved understanding of lifestyle change dynamics and more realistic, empirically-based quantitative simulations in climate mitigation pathways enriches scientific and policy analysis of how to achieve Paris Climate Agreement goals.

This is a pre-release dataset and is subject to change. The Climate Solutions Explorer website maps and presents information about mitigation pathways, avoided climate impacts, vulnerabilities and risks arising from development and climate change. www.climate-solutions-explorer.eu Using the latest data, state-of-the-art models were used to assess the future trends of indicators of development- and climate-induced challenges. Updated gridded global climate and impact model data are based on CMIP6 and CMIP5 projections, using a subset of models from the ISIMIP project that have been consistently downscaled and bias-corrected. The data includes various indicators (~30) relating to extremes of precipitation and temperature (e.g. from Expert Team on Climate Change Detection and Indices), hydrological variables including runoff and discharge, heat stress (from wet bulb temperature) events (multiple statistics and durations), and cooling degree days, as well as further indicators relating to air pollution (PM2.5 from the GAINs model), and crop yields and natural habitat land-use change (biodiversity pressure) from the GLOBIOM model. Indicators were calculated at a spatial resolution of 0.5° (approximately 50km at the equator), and subsequently spatially aggregated to the country level – from which population and land area exposure to the impacts were calculated. This has enabled the country-by-country comparison of national climate impacts and avoided exposure. Impacts were calculated at global mean temperature intervals, i.e. 1.2, 1.5, 2, 2.5, 3, and 3.5 °C, compared to a pre-industrial climate. The dataset includes: Global gridded projections (in netcdf format) of all the climate impact indicators at 0.5° spatial resolution, at global mean temperature intervals of 1.2, 1.5, 2, 2.5, 3, and 3.5 °C Tabular data (Excel .csv) is also provided, aggregating the impact indicators to the country level, for both hazards and exposure (both population and land) Further details on th

This dataset contains the parameterization of a no-policy baseline scenario of the global 11-regional MESSAGEix-GLOBIOM integrated assessment model. Regions, time periods, commodities, technologies and relations included in this model are described in a separate repository. The dataset relies on the MESSAGEix modeling framework (Huppmann et al. 2019) and can be imported into MESSAGEix via the read_excel() functionality for which a tutorial is available. After the import the scenario can be solved and modified to create new scenarios. Note that the published scenario as included in the ENGAGE global scenarios dataset has been run with a release candidate of version 3.4.0 of MESSAGEix.

The world is warming, and the demand for cooling is increasing. Developing a future green hydrogen economy will also increase the demand for cooling for hydrogen liquefaction. This increase in cooling demand will happen mainly in tropical and developing countries due to their increase in population, improvements in quality of life, and the export of their renewable potential with liquid hydrogen. To solve this increase in demand for cooling, this paper proposes the use of ammonia airship cooling (AAC). AAC extracts cold from the tropopause (−80 °C) with airships and ammonia refrigeration cycles. The liquid ammonia is then transported back to the surface to provide low temperature cooling services (−33 °C). This cooling service is particularly interesting for lowering the electricity consumption in hydrogen liquefaction plants. If all the technological challenges mentioned in the paper are addressed, it is estimated that the cost of cooling with the technology is 8.25 USD/MWht and that AAC could reduce the electricity demand for hydrogen liquefaction by 30%. AAC is an innovative renewable cooling technology that has the potential to complement other renewable energy sources in a sustainable future.

This dataset contains a set of climate scenario that have been developed for the Network for Greening the Financial System (NGFS). The NGFS is a group of 83 central banks and supervisors and 12 observers committed to sharing best practices, contributing to the development of climate– and environment–related risk management in the financial sector and mobilising mainstream finance to support the transition toward a sustainable economy. The scenarios in this dataset were produced by NGFS Workstream 3 in partnership with an academic consortium from the Potsdam Institute for Climate Impact Research (PIK), International Institute for Applied Systems Analysis (IIASA), University of Maryland (UMD), Climate Analytics (CA), the Eidgenössische Technische Hochschule Zürich (ETH) and the National Institute of Economic and Social Research (NIESR). The Phase 3 bespoke scenarios are generated by state-of-the-art well-established integrated assessment models (IAMs), namely GCAM, MESSAGEix-GLOBIOM and REMIND-MAgPIE. These models allow the estimation of global and regional mitigation costs, the analysis of energy system transition characteristics, the quantification of investments required to transform the energy system, and the identification of synergies and trade-off of sustainable development pathways. Technical documentation is available to help users access the datasets. The documentation describes the models and variables, as well as provides detailed guidance for database users. Scenario presentation materials and the user guide are also available at the NGFS portal.

Transition to low energy and material demand (LEMD) for buildings is key to reach climate change mitigation and sustainability targets but will require unprecedent technological and social transformations. Scenarios addressing LEMD transformations for the global building sector are still largely unexplored. In this study, we assess global residential energy and material demands until 2050 for three alternative sustainable development pathways (SDPs): Economy-driven innovation (EI), driven by technology and energy efficiency; Resilient communities (RC), a post-growth scenario centred around local communities and behavioural change; and Managing the global commons (MC), with strong global institutions and high electrification. We use the bottom-up framework MESSAGEix-Buildings, soft-linked to the integrated assessment model MESSAGEix-GLOBIOM, to model the three SDPs for the global residential sector. We show that the RC scenario entails the highest potential towards reducing energy and material demand driven by behavioural change. The EI and MC scenarios are characterized by relatively higher energy and material demand levels and might require additional efforts on the supply-side to reduce total building-related operational and construction greenhouse gases emissions. This study can support decision making on strategies towards sustainability and zero-energy and emission targets in the buildings sector.

The globe is witnessing a significant energy transformation with an increasing proportion of variable energy sources like wind and solar on the grid. Energy storage solutions are required to enable a seamless integration of these renewable energy sources. This paper presents a novel isothermal compressed air energy storage (CAES) consisting of two floating storage vessels in the deep ocean that operates by balancing the pressure of the upper and lower tanks with the oceanic pressure. The methodology consists of estimating the proposed system's energy storage potential and operational parametrization. Results show that the maximum compression ratio between the two storage vessels is four, which significantly increases the system's efficiency and lowers compression costs. Compressed air seesaw energy storage is a cheap alternative for storing compressed air because it does not require large, pressurized tanks or sand cavers. It is expected to cost between 10 and 50 USD/kWh for electric energy storage and between 800 and 1500 USD/kW for the installed power capacity. Seesaw is an interesting alternative to pumped hydro and hydrogen for long-term energy storage cycles in islands and coastal regions close to the deep sea.

Low-carbon energy transitions taking place worldwide are primarily driven by the integration of renewable energy sources such as wind and solar power. These variable renewable energy (VRE) sources require energy storage options to match energy demand reliably at different time scales. This article suggests using a gravitational-based energy storage method by making use of decommissioned underground mines as storage reservoirs, using a vertical shaft and electric motor/generators for lifting and dumping large volumes of sand. The proposed technology, called Underground Gravity Energy Storage (UGES), can discharge electricity by lowering large volumes of sand into an underground mine through the mine shaft. When there is excess electrical energy in the grid, UGES can store electricity by elevating sand from the mine and depositing it in upper storage sites on top of the mine. Unlike battery energy storage, the energy storage medium of UGES is sand, which means the self-discharge rate of the system is zero, enabling ultra-long energy storage times. Furthermore, the use of sand as storage media alleviates any risk for contaminating underground water resources as opposed to an underground pumped hydro storage alternative. UGES offers weekly to pluriannual energy storage cycles with energy storage investment costs of about 1 to 10 USD/kWh. The technology is estimated to have a global energy storage potential of 7 to 70 TWh and can support sustainable development, mainly by providing seasonal energy storage services.

Long-term global scenarios have underpinned research and assessment of global environmental change for the past decades. The climate change research community has developed a scenario framework combining alternative futures of climate and society to facilitate integrated research and assessment to inform policy. The framework uses the Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs), which together describe alternative visions of how society and climate may change over the coming decades, providing a framework for combining these pathways in integrated studies. Tracking the use of this framework in the literature allows for assessment of how it is being used, whether it is achieving its original goals, and what improvements to the framework would benefit future research. Researchers with the International Committee on New Integrated Climate Change Assessment Scenarios (ICONICS) tracked such literature, assessed analyzed results, and published the SSP Literature Database v1, which covered the articles from 2014 to 2019. The SSP Literature Database v2 contains citations, abstracts, and analyses of 1,134 articles published from 2020 to 2021 that used the SSPs. The articles were obtained from searches of Google Scholar, EBSCO, GeoRef, JSTOR, PAIS, ProQuest, Web of Science, and University of Helsinki’s library catalog. The articles include peer-reviewed publications (journal papers, book chapters) and other literature (working papers, reports, etc.). The database was generated by manual examination of the articles that made substantial use of the SSPs. Each article was then analyzed and coded according to different key tags, including categories of SSP application, the study type of publications, SSPs used in publications, and the societal and climate modeling combinations used. Some progress and specific changes have been made in v2 in light of the advances in the research community, such as the developments of the Coupled Model Inte

As urban areas are increasingly exposed to high temperatures, lack of access to residential thermal comfort is a challenge with dramatic consequences for human health and well-being. Air-conditioning (AC) can provide relief against heat stress, but a massive AC uptake could entail stark energy demand growth and mitigation challenges. Slums pose additional risks due to poor building quality, failing to provide adequate shelter from severe climatic conditions. Thus, it is unclear how many people in the Global South will still lack access to basic cooling under different future climate and socioeconomic developments. We assess the impact of different shared socioeconomic pathways (SSPs) and climate futures on the extent of population lacking access to cooling where needed—the cooling gap—and energy requirements for basic comfort for a set of 22 megacities in the Global South. We find that different SSPs greatly influence the extent of future cooling gaps, generally larger in SSP3 due low income levels, and consequent limited access to AC and durable housing. Megacities in Sub-Saharan Africa and South Asia have the largest share of population affected, ranging from 33% (SSP1) to 86% (SSP3) by mid-century. Energy requirements to provide basic cooling for all are higher in SSP1 for most megacities, driven by urbanization, and can increase by 7 to 23% moving from 2.0 to 3.0 °C temperature rise levels. Strategies combining improved building design and efficient cooling systems can improve adaptation to heat stress in cities while reducing energy and emission requirements to reach climate and sustainability goals.

The trade impacts of the COVID-19 pandemic and the Russian invasion of Ukraine have raised questions about the role of trade and climate policies in energy security and global emissions. This study updates a widely used integrated assessment model (IAM), MESSAGEix-GLOBIOM, to represent complex trade networks to explicitly draw energy flows from their origins to their destination. It then examines the effects of (1) energy trade tariff policies, such as import tariffs, as a proxy to represent an unfriendly trade environment and (2) a global carbon emissions tax on the global energy trade network. Results indicate that trade tariff policies have marginal effects on the trade network, i.e., the size of trade and importing-exporting regions do not change significantly. While high import tariffs significantly reduce emissions due to reduced fossil fuel imports in the importing region, this effect does not translate to significant emission reductions globally, as trade policies only impact downstream of the energy supply chain. However, a carbon emission tax dramatically alters the trade network, by (1) reducing its size by up to 50% and (2) forming trade linkages that allow for a more complex and diverse network of suppliers. This diversity under the emissions tax scenario improves the energy security of major energy-importing regions. Moreover, under an emission tax scenario, a friendly trade environment reduces the energy system costs globally. However, trade friction, such as sanctions or high import tariffs, will increase the energy supply cost significantly, especially for energy-importing regions such as Europe, East and South Asia.

We propose a mapping from NACE codes of economic activities, into Climate Policy Relevant Sectors (CPRS) and into the variables of the process-based Integrated Assessment Models (IAM) used by the Network for Greening the Financial System (NGFS) to provide its climate scenarios. We discuss the classification of CPRS at the disaggregation level provided by CPRS Granular, which distinguishes across energy technologies (e.g. within transport, motor vehicles powered by combustion vs electric engines). Then, we describe the mapping of NACE 4-digit – CPRS Granular – IAM variables used in the scenarios of the NGFS. CPRS enable users to group the large number of NACE codes into few categories of climate transition risk. At this point, it is possible to identify for each NACE economic activity the most relevant IAM variable to use in the NGFS scenarios. This procedure enables the use of climate scenarios (e.g. NGFS) for climate-related financial disclosure and climate stress testing. The goal of this note, and of the proposed mapping is to support practitioners, financial supervisors, investors and academics in climate transition risk disclosure and climate transition risk assessment, providing a science-based, transparent and operational tool.

Household solid waste (HSW) is the largest municipal solid waste (MSW) produced in Harare. This type of waste is poorly managed, driven by various factors. To inform future studies towards designing more informed solutions to HSW management in the city, this literature study was formulated. The review aims to uncover the causes of poor HSW management in the city. The systematic review methodology using NVIVO was used to develop the review. The results showed that the most reported causes of poor HSW management and waste management system inefficiencies in Harare are increase in population and population density, poor formal solid waste disposal, increase in waste volumes, informal waste disposal, low waste collection frequency and efficiency, municipal incapacitation, among others. Future studies can utilize these results to estimate the complexity of this phenomenon and thus propose appropriate solutions.

To reach the mitigation goals of the Paris Agreement, many countries will have to phase out their coal power plants prematurely, i.e., before the end of their normal lifetimes, which will lead quite possibly to significant stranded assets. This could present a major challenge, particularly for many of the rapidly developing countries whose electricity demand is growing and which are currently expanding their coal fleets. Recent research shows that countries with aging power plants and decreasing coal consumption are more inclined to phase out coal, but little is known about where, why, and how coal power plants are being prematurely retired. In the context of the hybrid Paris Agreement, attention is increasingly shifting to domestic mitigation capacities and, alongside this—given the vested interests involved in different sectors—to state capacity to implement the transformations required to achieve deep decarbonization. In this article, we aim to study those capacities in the context of coal phaseout. We use a recent and comprehensive global dataset on coal power plants and employ a mixed-methods research design to (a) identify general emerging patterns with respect to premature coal fleet retirement, and (b) derive stylized types of political strategies to prematurely retire coal power plants. We find state capacity to be a robust predictor of general and premature coal retirement, and we identify three main strategies that countries have used to date to prematurely retire coal: (a) rein-in using top-down regulatory enforcement of environmental, climate, or other regulations that affect the operating licenses of coal plants; (b) buy-out or provision of compensation to companies and regions to appease vested interests; and (c) crowd out where accelerating market and price dynamics in the power sector crowd out coal. We propose that future research should explore more systematically the kinds of strategy that might be most promising in the regions and countries need

Managing household solid waste (HSW) has gone beyond what the Harare local government can handle. Inadequate knowledge of the interactions existing between issues that affect the efficient running of waste management systems is one of the major hindrances in waste management planning in developing countries like Zimbabwe. The complexity of the waste management system for a given municipal area needs to be identified and understood to generate appropriate and efficient waste management strategies. Network analysis (NA) is a methodology extensively used in research to help reveal a comprehensive picture of the relationships and factors related to a particular phenomenon. The methodology reduces the intricacy of large systems such as waste management to smaller and more understandable structures. In this study, NA, which was done mainly using the R software environment, showed a result of 1.5% for network density, thus signifying that for Harare, waste management strategies need to be ‘seeded’ in various parts of the system. The Pareto principle and the 3Rs (Reduce, Reuse, Recycle) concept were applied to suggest the issues to prioritize and generate strategies that could potentially affect significant change to the city’s waste management system. The key issues identified, in their order of importance, are an increase in uncollected waste, low waste collection efficiency, increase in illegal waste dumping, the deteriorating country’s economy, reduced municipal financial capacity, reduced municipal workforce capacity, inadequate or unreliable waste data, increase in waste volume, increase in the number of street vendors, no waste planning and monitoring unit, no engineered landfills in the city, increase in waste collection pressure, low waste collection frequency, increase in the unemployment rate, reduced municipal technical capacity, few waste collection vehicles, limited vehicles maintenance, distinct socio-economic classes, high vehicles breakdown, and increase in

The Paris Agreement, adopted in 2015, paved the way for a new hybrid global climate governance architecture with both bottom-up and top-down elements. While governments can choose individual climate goals and actions, a global stocktake and a ratcheting-up mechanism have been put in place with the overall aim to ensure that collective efforts will prevent increasing adverse impacts of climate change. Integrated assessment models show that current combined climate commitments and policies of national governments fall short of keeping global warming to 1.5 °C or 2 °C above preindustrial levels. Although major greenhouse gas emitters, such as China, the European Union, India, the United States under the Biden administration, and several other countries, have made new pledges to take more ambitious climate action, it is highly uncertain where global climate policy is heading. Scenarios in line with long-term temperature targets typically assume a simplistic and hardly realistic level of harmonization of climate policies across countries. Against this backdrop, this article develops four archetypes for the further evolution of the global climate governance architecture and matches them with existing sets of scenarios developed by integrated assessment models. By these means, the article identifies knowledge gaps in the current scenario literature and discusses possible research avenues to explore the pre-conditions for successful coordination of national policies towards achieving the long-term target stipulated in the Paris Agreement.

A rapid global energy transition, including the ramping up of electricity generation from renewables, is needed to limit global warming to 2 °C or 1.5 °C. However, renewable resource endowments vary widely between regions, and renewable electricity is currently mainly used locally. Here we use a global integrated assessment model to explore the implications of renewable electricity trade via a set of planned direct-current-type ultra-high-voltage (UHVDC) transmission lines for global energy transition and climate change. We find that renewable electricity trade across large world regions via the underlying UHVDC interconnection can boost renewable electricity production and reduce 2020–2100 cumulative CO2 emissions from the power sector up to 9.8%. Financial investments in the UHVDC lines are offset in the long term by reduced investments in other electricity-generation options, including nuclear and storage. Finally, we find that renewable electricity trade can substantially reduce air pollutant emissions in importing regions.

This dataset contains a set of climate scenario that have been developed for the Network for Greening the Financial System (NGFS). The NGFS is a group of 83 central banks and supervisors and 12 observers committed to sharing best practices, contributing to the development of climate– and environment–related risk management in the financial sector and mobilising mainstream finance to support the transition toward a sustainable economy. The scenarios in this dataset were produced by NGFS Workstream 3 in partnership with an academic consortium from the Potsdam Institute for Climate Impact Research (PIK), International Institute for Applied Systems Analysis (IIASA), University of Maryland (UMD), Climate Analytics (CA), the Eidgenössische Technische Hochschule Zürich (ETH) and the National Institute of Economic and Social Research (NIESR). The Phase 3 bespoke scenarios are generated by state-of-the-art well-established integrated assessment models (IAMs), namely GCAM, MESSAGEix-GLOBIOM and REMIND-MAgPIE. These models allow the estimation of global and regional mitigation costs, the analysis of energy system transition characteristics, the quantification of investments required to transform the energy system, and the identification of synergies and trade-off of sustainable development pathways. Technical documentation is available to help users access the datasets. The documentation describes the models and variables, as well as provides detailed guidance for database users. Scenario presentation materials and the user guide are also available at the NGFS portal.

The world is undergoing a transition to a more sustainable energy sector dominated by renewable energy sources. This paper proposes an innovative solution that consists of catching water from streams at high altitudes to fill storage containers and transport them down a mountain, converting the potential energy of water into electricity with the regenerative braking systems of electric trucks and storing it in the truck's battery. The energy stored in the electric truck can be sold to the grid or used by the truck to transport other goods. Results show that the levelized cost of the electricity truck hydropower is 30–100 USD/MWh, which is cheap when compared with conventional hydropower 50–200 USD/MWh. The electricity generation world potential for the technology is estimated to be 1.2 PWh per year, which is equivalent to around 4% of the global energy consumption in 2019. Apart from being a low cost and impact electricity generation technology, electric truck hydropower can operate in combination with solar and wind resources and provide energy storage services to the grid.