Global and Regional Greenhouse Gas Emissions Neutrality

The issue of greenhouse gas neutrality as indicated in the Paris Agreement is increasingly gaining interest among policymakers. However, key questions need to be addressed before the concept could be used. The Paris Agreement is aimed to keeping global warming to well below 2 °C and to pursue efforts to limit it further, to 1.5 °C. These targets, in themselves, do not provide any guidance for policymakers and investors about how to achieve them. As part of a stocktaking process, policymakers are looking into various reduction targets and policy measures that could contribute to achieving the climate targets. The Paris Agreement also states the aim of global greenhouse gas emissions peaking as soon as possible, and of achieving a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century. The second aim is often referred to as the concept of greenhouse gas emissions neutrality, here defined as reducing global emissions of all greenhouse gases to net zero.

This publication discusses some of the relevant questions related to this concept. It includes an overview of the literature and of Integrated Assessment Model (IAM) runs and identifies knowledge gaps. It addresses the following three overarching policy questions:

1. What are the main principles of greenhouse gas emissions neutrality—and what key open questions are related to this concept?
2. What could be the global and regional implications of the emission pathways towards achieving greenhouse gas emissions neutrality?
3. What are the land-use implications of achieving greenhouse gas emissions neutrality?