Exploring Real Zero definitions

In many countries the support for “Net Zero” as a political goal is waning. Yet net zero emission targets remain essential in a geophysical sense to slow and ultimately halt future temperature increases.  Future emission pathways that are aligned with the Paris Agreement objectives typically reach net-zero carbon dioxide emissions by the middle of this century. They often go further and reach net-zero or net-negative greenhouse gas emissions later this century. Such scenarios comprise global gross emission reductions and carbon dioxide removals, via nature-based and or technological options. 

This work examines the changing political context around net zero and the need for a refreshed framing.  From a literature review, we have developed a set of principals for generating and evaluating future emission pathways based on their ability to limit the risks from future global warming  and limiting the risks of delivering successful emission mitigation. We discuss the necessity to preserve natural carbon sinks, and the need to consider intergenerational, regional and in-country equity and the perception of fairness.

Rapid phaseout of fossil fuel production and use emerges as a robust characteristic of the least risky Paris-Agreement aligned scenarios. We term these Real Zero scenarios and show that in such scenarios global progress can be accelerated with a greater focus on policy, technology and efficiency innovation to drive near term action.