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March 24, 2025
How can nationally determined contributions help countries reach net zero emissions?
Concepts within NDCs that help policymakers plan for a net-zero energy system
Summary
Energy system modellers use key terms like ‘net zero’, ‘peak emissions’, and ‘interim/mid-point targets’ to analyse NDCs and map out decarbonisation pathways.
Net zero describes a state in which any emissions released into the atmosphere are offset by the removal of carbon from the atmosphere.
Peak emissions describes a moment at which a country’s emissions are expected to be at their highest, before falling again on their path to net zero.
Interim and mid-point targets are ways of tracking the progress of a country towards its emissions reduction targets.
Nationally determined contributions (NDCs) are complex, holistic action plans for emissions reduction and rely on modelling of complex energy systems to derive actionable emissions targets. All modelling is based on assumptions about the future. In this explainer we’re introducing some additional concepts that underpin NDCs such as net zero, peak emissions, and interim emissions targets, which you’ll also encounter in TransitionZero's energy system modelling platform, Scenario Builder.
What is net zero?
Net zero means that emissions are zero in absolute terms: any emissions released are offset by ‘negative emissions’ to achieve a final balance of zero. This is in contrast to absolute zero emissions: a system that releases no emissions at all. The term can be applied to an individual asset, sector, or economy.
What do we mean by ‘negative’ emissions? This can be any pathway, natural or technological, that removes carbon from the atmosphere, such as direct air capture (DAC), carbon capture and storage (CCS), reforestation, and changes in land use.
Plan A, Net-zero journey, explained
Multiple countries have stated longer-term goals of net-zero emissions in addition to their 2030 NDC emissions reduction targets. These countries include the UK which is planning to achieve net zero by 2050, the EU (2050), Japan (2050), Canada (2050), Australia (2050), China (2060) and India (2070).
These targets are at different stages of legal and regulatory binding. For example, the UK has legislated their target whereas the US’s target is not legally binding. They also vary in terms of coverage. While some countries are aiming to achieve net-zero CO2 emissions within their energy systems specifically, others are aiming for net-zero greenhouse gas emissions across the whole economy.
Economy-wide net-zero targets can only be achieved by decarbonisation across all sectors. However, some sectors will decarbonise faster than others due to disparities in the availability and scalability of low-carbon technologies. For example, the power sector can use renewable technologies like battery storage, solar PV and wind power to decarbonise, whereas heavy industry and the transport sector lack viable alternatives to their processes.
The availability of scalable low-carbon technologies in the power sector is reflected by many countries setting net-zero CO2 emissions goals there years before an economy-wide target. For example, Fiji aims to achieve net-zero emissions for its power sector by 2030, 20 years ahead of its economy-wide net-zero target of 2050.
What is peak emissions?
Non-Annex I countries often set peak emissions targets rather than immediate absolute reductions because their economies are still growing, and they need to expand infrastructure, industry, and energy access to support development. This is in alignment with the common but differentiated responsibilities (CBDR) framework, and allows them to continue growing while committing to a future turning point, after which emissions will decline.
For example, China and Argentina have stated in their NDCs that peak emissions will occur by 2030, while Chile is aiming for 2025.
What are interim and mid-point emissions targets?
Interim and mid-point emissions targets both provide a checkpoint, keeping a country on track for its longer-term emissions reduction goals.
The table below shows some example interim emissions targets for 2025, with the reductions considered ‘checkpoints’ on a country’s path towards meeting its NDC target in 2030.
What’s next?
To see how these concepts interact with real-world energy systems models, visit our platform.
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