Scenarios limiting global warming to 1.5°C describe major transformations in energy supply and everrising energy demand. Here we provide a contrasting perspective by developing a narrative of future change based on observable trends that results in low energy demand. We describe and quantify changes in activity levels and energy intensity in the Global North and South for all major energy services. We project that global final energy demand by 2050 reduces to 245 EJ, around 40% lower than today despite rising population, income and activity. Using an integrated assessment modelling framework, we show how changes in the quantity and type of energy services drive structural change in intermediate and upstream supply sectors (energy and land use). Down-sizing the global energy system dramatically improves the feasibility of low-carbon supply-side transformation. Our scenario meets the 1.5°C climate target as well as many Sustainable Development Goals, without relying on negative emission technologies. * Contingency reserve of 8 EJ is allocated equally to Global North and South respectively. Bunker fuels are reported at the global level only, consistent with current energy balances and emission accounting frameworks. Activity level units vary per end-use service and upstream sector: a billion m 2 of floor space; b trillion passengerkilometres; c billion tonnes of materials; d trillion tonne-kilometres.

Low-carbon investments are necessary for driving the energy system transformation called for by both the Paris Agreement and Sustainable Development Goals. Improving understanding of the scale and nature of these investments under diverging technology and policy futures is therefore of great importance to decision makers. Here, using six global modelling frameworks, we show that the pronounced reallocation of the investment portfolio required to transform the energy system will not be initiated by the current suite of countries' Nationally Determined Contributions. Charting a course toward 'well below 2 °C' instead sees low-carbon investments overtaking fossil investments globally by around 2025 or before and growing significantly thereafter. Pursuing the 1.5 °C target demands a marked up-scaling in low-carbon capital beyond that of a 2 °C-consistent future. Actions consistent with an energy transformation would increase the costs of achieving energy access and food security goals but reduce those for achieving air quality goals.

Scenarios have been supporting assessments of the Intergovernmental Panel on Climate Change (IPCC) for decades. A new scenario database and a suite of visualisation and analysis tools is now made available alongside the IPCC 1.5°C Special Report to improve transparency and re-use of scenario data across research communities. Over the past two years, the IPCC has been preparing a Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways 1 (SR1.5). This process was initiated at the explicit invitation of the 193 governments of the United Nations Framework Convention on Climate Change 2 (UNFCCC) as part of the decisions taken in Paris in 2015. During the first week of October in 2018, the resulting report, at more than 200 pages, was presented for approval by the IPCC plenary in Incheon, South Korea. The report assesses the state of scientific knowledge for a large range of 1.5°C-related issues. Amongst these are the required system transitions and options for strengthening the global response to climate change in the context of the sustainable development goals (SDG), including efforts to eradicate poverty and improving health globally. A new scenario resource When it comes to assessments of long-term transformations across the energy sector, land-use change and agriculture, and social dimensions, integrated assessment models (IAM) are an essential resource in the scientists' toolbox. IAMs allow to quantify storylines of future development and can, for example, be used to analyse impacts of various policies or the availability of specific technologies on energy

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Many countries have implemented national climate policies to accomplish pledged Nationally Determined Contributions and to contribute to the temperature objectives of the Paris Agreement on climate change. In 2023, the global stocktake will assess the combined effort of countries. Here, based on a public policy database and a multi-model scenario analysis, we show that implementation of current policies leaves a median emission gap of 22.4 to 28.2 GtCO 2 eq by 2030 with the optimal pathways to implement the well below 2°C and 1.5°C Paris goals. If Nationally Determined Contributions would be fully implemented, this gap would be reduced by a third. Interestingly, the countries evaluated were found to not achieve their pledged contributions with implemented policies (implementation gap), or to have an ambition gap with optimal pathways towards well below 2°C. This shows that all countries would need to accelerate the implementation of policies for renewable technologies, while efficiency improvements are especially important in emerging countries and fossilfuel-dependent countries.