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. The newly published IPCC (2018) special report on Global Warming of 1.5°C (SR15) states “Reaching and sustaining net zero global anthropogenic CO2 emissions and declining net non-CO2 radiative forcing would halt anthropogenic global warming on multi-decadal timescales”.

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. This is highlighted through some general comments about the concept, and the example of some scenarios.

This Technical Note was prepared in the project Climate Recon 2050: Dialogues on Pathways and Policies https://climatedialogue.eu