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

Published online by Cambridge University Press:  19 June 2023

Hannah Parris*
Affiliation:
Climate Change Policy Group, Centre for Atmospheric Sciences, University of Cambridge
Annela Anger-Kraavi
Affiliation:
Climate Change Policy Group, Centre for Atmospheric Sciences, University of Cambridge
Glen P. Peters
Affiliation:
CICERO Center for International Climate Research, Oslo, Norway
*
Author for correspondence: Hannah Parris, E-mail: hrp44@cam.ac.uk or hannahruthparris@gmail.com

Abstract

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?

Information

Type
Research Article
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
Copyright © The Author(s), 2023. Published by Cambridge University Press
Figure 0

Figure 1. Global pathways from 2010.Source: Authors' own analysis. Historical emissions (Friedlingstein et al., 2022) branch into different pathways with cumulative emissions that do not exceed a remaining carbon budget of 500GtCO2, broadly consistent with staying below 1.5 °C of warming (IPCC, 2021 Table SPM.2). The different pathways have the same cumulative emissions, but different pathways towards net zero, leading to different near term reduction rates and different net zero years. There are also pathways that stay within the remaining carbon budget, but never actually cross zero (they have no net zero year). The net zero years occur before 2050, as many scenarios assessed by the IPCC actually exceed 1.5 °C first, before returning later, which can push the net zero year back to later years.

Figure 1

Table 1. Sample of global net zero emissions initiatives

Figure 2

Table 2. Demographic split of respondents (survey)

Figure 3

Table 3. Demographic characteristics of interviewees

Figure 4

Table 4. Source of climate information

Figure 5

Figure 2. (a) Flexible versus stable policy targets (all respondents). (b) Flexible versus stable policy targets (negotiators only). (c) Flexible versus stable policy targets (observers only). (d) Flexible versus stable policy targets (developed country respondents only). In the survey, the answer categories were group according to income levels and emission levels as follows Group 1: China, India, Russia, Brazil, Indonesia, Group 2: Other developing countries, Group 3: US, EU, Canada, UK, Japan, Group 4: Other developed countries. For the sake of brevity in Table 2, Groups 1 and 2 were collated under the heading of ‘developing countries’ and groups 3 and 4 are collated under the heading ‘developed countries’. (e) Flexible versus stable policy targets (developing country respondents only).

Figure 6

Table 5. Descriptive statistics (mean, median, mode, SE, CI)

Figure 7

Table 6. Distribution of responses across the answer scale

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