Technical Note 6: Modelling net zero emissions

In the last years the aim of "reaching net zero emissions" gained political momentum. The Paris Agreement aims for "a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century" (Article 4 No 1). Also the EU Governance Regulation mentions "net zero greenhouse gas emissions within the Union by 2050" (Regulation (EU) 2018/1999, Article 15, No 2 (a)). These political intentions are backed by the scientific consensus.

Building compliance with the Paris Agreement will require developing policies and measures aiming for this "net zero" goal. It is therefore crucial that long-term scenarios explore the options and set the possible pathways to meet this objective. This is not only about upgrading existing scenarios: modelling "net zero" is a new challenge, raising new issues about the comprehensiveness, geographic perimeter or timescale of the scenarios, as well as calling for considering further technical or societal options.

In the first part of this Technical Note we discuss the definition and implication of net zero emissions. For example, differences between carbon-neutral and climate-neutral or net zero emissions and emission budgets are explained. The second part presents three case studies. First the "Climate Protection Scenario 2050" for Germany, second the "négaWatt 2017-2050" scenario for France and third the Nordic "NETP/IPCC 2014" scenario for the Scandinavian region. The third and last part is a general conclusion from the three scenarios.