The IEA’s medium- to long-term outlook publications – including the World Energy Outlook (WEO) and Energy Technology Perspectives (ETP) – use a scenario approach relying on the Global Energy and Climate (GEC) Model to examine future energy trends. The GEC Model is used to explore various scenarios, each of which is built on a different set of underlying assumptions about how the energy system might evolve over time. By comparing them, readers can assess what drives the various outcomes, and the opportunities and pitfalls that lie along the way. These scenarios are not predictions, and do not contain a single view about what the long-term future might hold. Instead, the scenarios seek to enable readers to compare different possible versions of the future, and the levers and actions that produce them, and to gain insights into the future of global energy.

The World Energy Outlook, Energy Technology Perspectives and their related reports explore different aspects of three scenarios, all of which are fully updated to include the latest energy market and cost data. The Net Zero Emissions by 2050 Scenario (NZE Scenario) is normative, in that it is designed to achieve specific outcomes – an emissions trajectory consistent with keeping the temperature rise in 2100 below 1.5 °C (with at least a 50% probability) with limited overshoot, universal access to modern energy services by 2030 and major improvements in air quality – and shows a pathway to reach them. The Announced Pledges Scenario (APS) and the Stated Policies Scenario (STEPS) are exploratory, in that they define a set of starting conditions, such as policies and targets, and see where they lead based on model representations of energy systems that reflect market dynamics and technological progress.

The scenarios highlight the importance of government policies in determining the future of the global energy system: decisions made by governments are the main differentiating factor explaining the variations in outcomes across our scenarios. However, we also account for other elements and influences, notably the economic and demographic context, technology costs and learning, energy prices and affordability, corporate sustainability commitments, and social and behavioural factors. While the evolving costs of known technologies are modelled in detail, we do not try to anticipate technology breakthroughs (such as nuclear fusion).

The Intergovernmental Panel on Climate Change (IPCC) Working Group III Sixth Assessment Report on climate change mitigation, released in April 2022, assessed a large number of scenarios that led to at least a 50% chance of limiting the temperature rise to 1.5 °C in 2100. As the figure makes clear, the NZE Scenario trajectory is well within the envelope of these scenarios.

To achieve the goal of limiting temperature rise, the Paris Agreement calls for emissions to peak as soon as possible and decline rapidly thereafter, leading to a balance between anthropogenic emissions by sources and removals by sinks (i.e. net zero emissions) by the year 2050. These conditions are all met in the NZE Scenario.

The Paris Agreement is clear that climate change mitigation objectives should be fulfilled in the context of sustainable development and efforts to eradicate poverty. The NZE Scenario explicitly supports these broader development efforts, in particular with respect to energy access and air pollution. In the NZE Scenario, there is no trade-off between achieving climate objectives and delivering on energy access and air pollution goals. Good policy design can exploit synergies between the three parallel objectives of the scenario.

Universal access to modern energy is achieved by 2030 in the NZE Scenario. Strong policy support and international co-operation enable a ramping-up of progress on expanding access programmes to achieve universal access to electricity and clean cooking by 2030, in line with Sustainable Development Goal 7. Achieving universal energy access will transform the lives of hundreds of millions of people and reduce the severe health impacts of indoor air pollution, overwhelmingly caused by smoke from cooking. Achieving universal access to modern energy leads to a net reduction in greenhouse gas emissions, largely thanks to lower methane emissions from the traditional use of biomass.

In the APS, all country targets for access to electricity and clean cooking (see table above) are achieved on time and in full. By 2030 this leads to a 60% and 68% reduction in the share of the population without access to electricity and clean cooking, respectively. However, this would still mean that there are 290 million people without access to electricity and 780 million without access to clean cooking.

Polluted air has caused at least 19 000 excess deaths per day in recent years and comes with significant economic costs. Some are direct costs, such as those due to the provision of healthcare, and some are indirect, such as those incurred because of labour productivity losses or crop damage.

While the STEPS and the APS see rising numbers of people exposed to heavily polluted air during the next decade, the NZE Scenario leads to dramatic reductions as set out in Sustainable Development Goal 3 (target 3.9). By 2050, around 2 billion fewer people breathe heavily polluted air.

The IEA began exploring scenarios to limit CO₂ emissions in 2006, with the ETP Accelerated Technology (ACT) Scenarios that sought to curb emissions growth by bringing emissions back down to 2005 levels by 2050. This analysis continued with the ETP BLUE Map Scenario in 2008, which targeted a 50% reduction in CO₂ emissions by 2050, and later evolved into the 2 °C Scenario (2DS).

Several special reports designed to feed into United Nations Framework Convention on Climate Change (UNFCCC) Conference of the Parties (COP) negotiations have examined the energy implications of climate scenarios in depth. These include:

• The World Energy Outlook 2008, which assessed two scenarios in which the atmospheric concentration of emissions stabilised at 550 parts per million (ppm) and 450 ppm respectively, to inform the design of a post-Kyoto climate framework at COP 15 in Copenhagen in 2009.
• Redrawing the Energy-Climate Map, a World Energy Outlook special report published in 2013, that fed into COP 19 in Warsaw, setting out key measures for the energy sector to stay within the 2.0 °C target and make further reductions.
• The World Energy Outlook 2015 Special Report on Energy and Climate Change, which contributed to preparations for COP 21 in Paris with a detailed assessment of how national climate pledges impact the energy sector.