Net-zero emission targets for major emitting countries consistent with the Paris Agreement

Heleen L Van Soest,Michel G J Den Elzen,Detlef P Van Vuuren

doi:10.1038/s41467-021-22294-x

Heleen L Van Soest, Michel G J Den Elzen + Show 1 more

Open Access

https://doi.org/10.1038/s41467-021-22294-x

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Abstract

Over 100 countries have set or are considering net-zero emissions or neutrality targets. However, most of the information on emissions neutrality (such as timing) is provided for the global level. Here, we look at national-level neutrality-years based on globally cost-effective 1.5 °C and 2 °C scenarios from integrated assessment models. These results indicate that domestic net zero greenhouse gas and CO2 emissions in Brazil and the USA are reached a decade earlier than the global average, and in India and Indonesia later than global average. These results depend on choices like the accounting of land-use emissions. The results also show that carbon storage and afforestation capacity, income, share of non-CO2 emissions, and transport sector emissions affect the variance in projected phase-out years across countries. We further compare these results to an alternative approach, using equity-based rules to establish target years. These results can inform policymakers on net-zero targets.

Highlights

Over 100 countries have set or are considering net-zero emissions or neutrality targets
Parties further agreed to “reach global peaking of greenhouse gas emissions as soon as possible [...] and [...] to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century.” (Article 4)[1]. This balance between greenhouse gas (GHG) emission sources and sinks can be defined as GHG emissions neutrality[2]. This is elaborated by Rogelj et al.[3] who define carbon neutrality as the total annual CO2 emissions from all anthropogenic sources being net-zero and GHG emissions neutrality as the sum of all Kyoto GHG emissions being net zero
It further depends on the interpretation of the word balance in Article 4 of the Paris Agreement[7], e.g., whether it corresponds to stable global mean temperature, radiative forcing or emissions, and whether it includes only anthropogenic or all GHG sources and sinks[8]

Summary

Introduction

Over 100 countries have set or are considering net-zero emissions or neutrality targets. We look at national-level neutrality-years based on globally cost-effective 1.5 °C and 2 °C scenarios from integrated assessment models These results indicate that domestic net zero greenhouse gas and CO2 emissions in Brazil and the USA are reached a decade earlier than the global average, and in India and Indonesia later than global average. IAMs have developed to represent individual countries and current climate policies in more detail, IAMs are not the only tools for analyses such as presented here—national energy system models, e.g., can do so too, often with greater granularity These tools are already applied jointly to develop national-level pathways that account for national circumstances but still meet the global goals of the Paris Agreement. The results that we present here should be complemented with an assessment of feasible reductions at the national level, considerations of equity and national model results, among others

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Results

Conclusion