Energy system transitions and low-carbon pathways in Australia, Brazil, Canada, China, EU-28, India, Indonesia, Japan, Republic of Korea, Russia and the United States

Highlights

• We explore national low-carbon emission scenarios for eleven regions of the globe.

• We use country-level technology-rich energy-economy and integrated assessment models.

• These models include detailed representations of the energy, transport and land systems.

• We provide insights on emissions, energy system and economic implications up to 2050.

Abstract

The Paris Agreement invited Parties to develop low-emission development strategies. This study presents national low-emission scenarios to inform such strategies for Australia, Brazil, Canada, China, EU-28, India, Indonesia, Japan, Republic of Korea, Russia and the USA. We use country-level technology-rich energy-economy and integrated assessment models that include detailed representations of the energy, transport and land systems and provide insights on emissions, energy system and economic implications of low-emission pathways until 2050. We show that the low-emission pathways of most economies studied here are consistent with pathways limiting global temperature increase to well-below 2 °C, while emission reductions are achieved through uptake of renewable energy, energy efficiency improvements and electrification of energy services. The role of mitigation options like nuclear, carbon capture and storage (CCS) and advanced biofuels is differentiates across countries, depending on national priorities, specificities and resource endowments. The energy system transformation requires a pronounced reallocation of investments towards low-carbon technologies, but without raising significant affordability issues in most countries. National pathways improve the consistency between country policy plans with global temperature goals and capture structural heterogeneities and broad socio-economic considerations.

Introduction

As part of the Paris conference in 2015, governments agreed to limit global warming to levels “well below 2 °C″ relative to pre-industrial levels [1] and to pursue efforts to limit it to 1.5 °C. This requires staying within the remaining emissions budget of approximately 420–1200 Gt of CO₂ by 2100 [2,3]. In this context, more than 190 countries worldwide submitted their Nationally Determined Contributions (NDCs), outlining voluntary climate actions until 2030 and considering national development goals, including the United Nations Sustainable Development Goals (SDGs) [4]. As the country contributions do not add up to the mitigation effort needed to limit temperature increase to well-below 2 °C or 1.5 °C [4,5], the Paris Agreement (PA) requires Parties to periodically submit a revised, more ambitious NDC and mandates global stocktaking exercises every five years, starting in 2023, to assess progress against the global targets. In addition, countries should “formulate and communicate low GHG emission development strategies” (Article 4.19) considering common but differentiated responsibilities. The national long-term strategies can inform increasingly ambitious carbon abatement targets, while ensuring consistency with SDGs and national priorities. So far only few countries have officially submitted their strategies to the UNFCCC.¹

Low-emission strategies enables the reconciliation of the long-term and global horizon of the climate targets with the short and medium-term nature and national scale of climate policies to inform decision making at national and international levels [6]. A long-term strategy describes how a nation could reduce emissions while enhancing its socio-economic development. These strategies may help countries to develop their medium and long-term emissions trajectories compatible with the Paris objectives ensuring the implementation of their climate targets. Long-term strategies informed by model-derived energy-economy pathways would ensure consistency of national policy and investment decisions with long-term climate targets [7] aiming to avoid disruption and lock-in risks, manage the transition process and increase co-benefits of mitigation while safeguarding their development from climate damages. First climate movers can set the example for increased policy ambition in other countries, resulting in accelerated climate action globally [8], while revealing the key enabling conditions for emission abatement such as technology transfer, low-cost climate finance, and institutional support.

Global modelling approaches commonly using Integrated Assessment Models (IAMs) are extensively used in IPCC Assessment and Special Reports [2,9] and to inform stakeholders on low-emission development strategies as they can provide useful insights on the systemic restructuring required for the low-emission economy. Recent studies using global IAMs have explored the impact of national climate policies [10], technology upscale requirements [11], socio-economic aspects [12], the effort induced by NDCs [13], energy system transformation [14], timing of the mitigation effort [8], and interplay with SDGs [15].

Global models can investigate potential pathways for reaching global climate targets, but this approach has limitations to support the national policy instruments outlined in the PA [16]. Most global models (with limited exceptions like [10]) adopt simplified representations of the complex energy-land-climate-economy systems and do not adequately represent specific national circumstances, policy measures and objectives [17]; for example [14], showed that most IAMs do not sufficiently capture the evolution of the Japanese electricity sector following the nuclear accident and do not easily capture intersectoral dynamics, synergies and trade-offs among mitigation options [18]. The aggregate regional representations combined with the simplified techno-economic and social assumptions may fail to represent national emission reduction plans, potentials, limitations and sector-specific policy measures [19].

Country-scale assessment of ambitious climate objectives has also been conducted for many countries across Europe [20,21], North America [22], Asia [23,24], and Latin America [18,25]. In multi-country studies, national teams investigate local low-emission strategies [26,27]. However, most national-scale studies do not adequately capture the international context, as boundary constraints are not commonly developed based on the global transition context, for example carbon budgets, global fossil fuel prices and technological assumptions [20]. Recently [6], proposed a new design framework for low-emission country-scale pathways based on designing country-driven narratives in an iterative nature that are then converted into quantitative scenarios using analytical tools (e.g. national models), which report their results for a set of indicators. However, the approach does not guarantee compatibility of national pathways with the global carbon budget required to achieve the PA goals, while the sectoral benchmarks that guide the development of low-emission pathways were chosen arbitrarily and do not sufficiently reflect differences and heterogeneities among countries [28]. In addition, the lack of comprehensive modelling at the national and global level implies that the study does not capture the complex dynamics of the interlinked energy-economy-environmental system including sectoral transformations, system integration and behavioural change.

Bottom-up national-scale approaches and global IAMs can provide complementary insights on the potentials and implications of low-emission strategies, enabling the representation of both country policy priorities and circumstances and international climate targets. New methodological approaches are required to rigorously analyse the national and international impacts of low-emission targets and combine the key strengths of country and global-scale modelling approaches [13,29]. This study attempts to fill this research gap and develops a hybrid approach aiming to combine key strengths of global IAMs and comprehensive national-scale models to develop a robust methodological framework facilitating the formulation and design of policy-relevant national low-emission development strategies fully considering country-level priorities, such as sustainable development, energy security, and job creation. To this end, a series of state-of-the-art national-scale models for eleven economies is utilised, thus enhancing the credibility and realism of model-based assessments by considering national-level specificities, heterogeneities, plans and policy measures. We explore the impacts of long-term low-emission scenarios on emission trajectories, energy system transformation, uptake of clean technologies and investment requirements in eleven major emitting economies in a cross-country context, while the consistency of country-level low-emission strategies with the Paris goals is assessed using the results of leading global IAMs² that formed the backbone of analysis in recent IPCC reports. Using rigorous state-of-the-art country-level modelling tools with enhanced representation of national policies and priorities and the complex interlinkages between energy demand, supply, prices, land uses and the economy, we improve the bottom-up national scale mitigation assessments.

The study provides insights related to the design and formation of country low-emission strategies compatible with national circumstances, policy priorities and country-specific development objectives, assess the compatibility of the collective ambition towards the PA mitigation goals and explore the systemic transformation and investment requirements of these strategies. In this way, it fosters continued interactions and scientific dialogue between country and global teams with the development of national low-carbon strategies that are compatible with the PA goals and considers both global climate targets and national priorities and circumstances (i.e. employment, energy security). The study provides new insights on low-emission transition pathways in eleven economies, as updated information and recent policy developments are integrated for major emitters (Brazil, EU, Japan, China, India, Russia, USA), while the analysis expands to countries that are not commonly represented in IAMs (Australia, Canada, Korea, Indonesia). The assessment of local mitigation barriers and potentials may inform and improve country representations in leading IAMs.

We move beyond [13] by (i) expanding the time horizon of the study to 2050 to explore long-term low-emission national pathways, (ii) adding more countries to the analysis, (iii) assessing the consistency of national low-emission strategies with the global PA goals, and (iv) exploring a common set of sectoral transformation indicators and investment requirements across countries. To enhance the transparency of mitigation pathways, all model-based scenarios are included in an online, easily accessible database³ while data processing routines are used for information exchange.