The Cancun Agreement had previously established a goal of limiting global temperature to “below 2 ☌” 8, which was interpreted by the scientific community as a 66% probability (or “likely” chance) of maintaining this limit 9.
Whereas the climate outcomes of the IAM pathways were assessed by the SR1.5 author team, the temperature statements of the non-IAM pathways were self-assessed.Īssessing if a given emissions mitigation pathway (here, we use the term scenario synonymously) adheres to the Paris Agreement requires some historical context of the climate negotiation process. The SR1.5 database also included a small selection of non-IAM pathways (including two scenarios from the IEA, and one from Shell). A large number of emission mitigation pathways generated by IAMs have been previously assessed and categorized with respect to their climate outcomes in SR1.5 5, 7. Most IAMs represent different greenhouse gases and aerosol precursors over a long-term horizon (2100), a necessary characteristic for assessing the consistency with the Paris Agreement LTTG. Normative scenarios are explicitly associated with the achievement of a desired end state (in this case, a temperature goal) and have primarily been the subject of investigation by the Integrated Assessment Modeling (IAM) community. Outlooks are short- to medium-term projections or forecasts, whereas exploratory scenarios represent a range of plausible futures. propose a categorization of energy system scenarios in terms of being outlooks, exploratory, or normative 6. The ruling draws on scenarios from the International Energy Agency (IEA) and Shell, in addition to mitigation pathways underlying the Intergovernmental Panel on Climate Change (IPCC) Special Report on 1.5 ☌ (SR1.5) 5. We can observe this influence, for example, in the ruling of the Hague District Court, which directed Royal Dutch Shell (Shell) to reduce (net) emissions by 45% below 2019 levels, by 2030 4. Importantly, such authoritative sources also affect planning and decision making by investors 3 who aim to anticipate climate policies, and their decisions in turn can drive or hold back setting ambitious emissions reduction targets. The foundations on which country targets are based are guided, directly or indirectly, by a variety of sources of information judged to be authoritative, including scientific research institutes 2, international agencies, or private companies. Governments have submitted or are preparing updates of their Nationally Determined Contributions (NDCs) and are encouraged to submit long-term low greenhouse gas development plans (Article 4 of the Agreement 1), aimed at aligning short- and long-term strategies. Since its adoption in 2015, governments, international agencies and private entities have increasingly recognized the implications of the Paris Agreement’s 1.5 ☌ long-term temperature goal (LTTG) for greenhouse gas emissions reduction planning in both the near- and long-term. We investigate root causes for misalignment with these criteria based on the underlying energy system transformation. Of the scenarios assessed, we find that only the IEA Net Zero 2050 scenario is aligned with the criteria for Paris Agreement consistency employed here. An evaluation of peak and end-of-century temperatures is made, with both being relevant to the Paris Agreement goal. We harmonize emissions to a consistent base-year and account for all greenhouse gases and aerosol precursor emissions, ensuring a self-consistent comparison of climate variables. We compare a selection of these scenarios analysed with this methodology to the Integrated Assessment Model scenarios assessed by the Intergovernmental Panel on Climate Change. Here we employ a uniform and transparent methodology to evaluate Paris Agreement compatibility of influential institutional emission scenarios from the grey literature, including those from Shell, BP, and the International Energy Agency.
Scientifically rigorous guidance to policy makers on mitigation options for meeting the Paris Agreement long-term temperature goal requires an evaluation of long-term global-warming implications of greenhouse gas emissions pathways.
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