Does a change in the ‘global net zero’ language matter?

Non-technical summary Changes in language used in long term climate policy can undermine their credibility and discourage climate action. Previous IPCC reports have promoted an idea of reaching ‘global net zero’ (GNZ) emissions by 2050 in order to limit global warming to 1.5 °C. In the latest IPCC Report, this language has been changed. To understand the impact of this change, we survey COP 26 participants to test their willingness to accept a shift in long term policy goals. We find a low tolerance for a change and, indeed, there is substantial finance, business and political effort behind the idea of reaching GNZ by 2050. This suggests that GNZ by 2050 will remain central to climate action. Technical summary Consistency in language in long term policy goals is central to building a (political) constituency in support of the Paris Agreement. Changes in language can undermine policy credibility, and stall effective mitigation action. Recent changes in IPCC language to describe ‘global net zero’ (GNZ) as being reached in the ‘early or mid 2050s’ (AR6 WG1) could risk undermining the substantial cultural, political and financial momentum that has developed behind the interpretation – first developed by the IPCC SR 1.5 °C Report – that GNZ must be reached by 2050. We survey COP 26 participants to test their willingness to accept a shift in policy goals and find a strong preference for a ‘stable’ long term policy target, widely interpreted as reaching ‘GNZ by 2050’, and a rejection of flexibility in long term policy targets, even as new scientific information becomes available. ‘GNZ by 2050’ is no longer a science based target, but has transitioned to a cultural and political metaphor actively used by stakeholders to guide their climate decision making. This makes ‘GNZ by 2050’ no less valid than the original scientific concept. This may stimulate further ‘political calibration’ or between the policy and modelling communities. Social media summary Sig. momentum is behind global net zero by 2050.Will changes in IPCC mitigation language de-rail global climate action?