Gaurav Ganti

and 6 more

Addressing questions of equitable contributions to emission reductions is important to facilitate ambitious global action on climate change within the ambit of the Paris Agreement. Several large developing regions with low historical contributions to global warming have a strong moral claim to a large proportion of the remaining carbon budget. However, this claim needs to be assessed in a context where the remaining carbon budget consistent with the Long-Term Temperature Goal (LTTG) of the Paris Agreement is rapidly diminishing. Here we assess the potential tension between the moral claim to the remaining carbon space by large developing regions with low per capita emissions, and the collective obligation to achieve the goals of the Paris Agreement. Based on scenarios underlying the IPCC’s 6th Assessment Report, we construct a suite of scenarios that combine the following elements: (i) two quantifications of a moral claim to the remaining carbon space by South Asia, and Africa, (ii) a “highest possible emission reduction” effort by developed regions, and (iii) a corresponding range for other developing regions. We find that even the best effort by developed regions cannot compensate for a unilateral claim to the remaining carbon space by South Asia and Africa. This would put the LTTG firmly out of reach unless other developing regions cede their moral claim to emissions space and, like developed regions, pursue highest possible emission reductions. Furthermore, regions such as Latin America would need to provide large-scale negative emissions with potential risks and negative side effects. Our findings raise important questions of perspectives on equity in the context of the Paris Agreement including on the critical importance of climate finance. A failure to provide adequate levels of financial support to compensate large developing regions to emit less than their moral claim will put the Paris Agreement at risk.
Since its adoption, the Paris Agreement sets and defines the global climate ambition. The overall scope of this ambition is expressed in its long-term temperature goal in Article 2 as well as the ‘net zero’ mitigation goal in Article 4. To provide guidance to climate policy, the scientific community has explored the characteristics of greenhouse gas (GHG) emission reduction pathways that can meet the Paris Agreement goals. However, when categorizing and presenting such pathways including in reports of the Intergovernmental Panel on Climate Change (IPCC), the focus has been put on the temperature outcome and not on the emission reduction criteria set out in Article 4.1. Here we propose a pathway classification approach that aims to comprehensively reflect all climate criteria set out in the Paris Agreement. We show how such an approach allows for an internally consistent interpretation of the Paris Agreement in terms of emission reduction pathways. For pathways that simultaneously are very likely to hold warming to below 2°C, pursue efforts to limit warming to 1.5°C and achieve the provisions outlined in Article 4.1, we report 2030 global Kyoto-GHG emissions of between 20-26 Gt CO2eq (interquartile range), net zero CO2 emissions around 2050 and net zero GHG emissions around 2060. We further illustrate how prevalent pathway classifications focusing, for example, on the temperature outcome in 2100 result in additional criteria being applied that are not rooted in the Paris Agreement. We outline the consequences of such approaches including for the deployment of carbon dioxide removal (CDR) in such pathways. We find that across pathways classified as ‘no or low overshoot’ pathways in previous IPCC reports, such non-Paris related, additional criteria for end-of-century outcomes may lead to about 20% higher CDR deployment compared to purely achieving the Paris Agreement objectives in mitigation pathways.