The Conference of the Parties, by its decision 1/CP.21, paragraph 21, invited the IPCC to provide in 2018 a special report on impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways. In the same decision, paragraph 17 also specifically refers to the special report. The COP noted that much greater emission reduction efforts will be required than those associated with the intended nationally determined contributions in order to hold the increase in the global average temperature to below 2 ˚C above pre-industrial levels by reducing emissions to 40 gigatonnes or to 1.5 ˚C above pre-industrial levels by reducing to a level to be identified in the special report.

The special report will feed in to the UNFCCC process in different ways including, inter alia, through:

• On-going cooperation between the UNFCCC process and the IPCC.
• The Subsidiary Body for Scientific and Technological Advice (SBSTA): the SBSTA plays an important role as the link between the scientific information provided by expert sources such as the IPCC and the policy-oriented needs of the COP. The SBSTA hosts SBSTA-IPCC Special Events, as needed, to share information and create dialogue around IPCC products and work.
• Nationally-Determined Contributions (NDCs): the report will inform the next round of NDCs on the collective mitigation action needed for maintaining a reasonable chance to limit global warming at 1.5°C, including by providing the estimated aggregate greenhouse gas emission levels in 2025 and 2030 for such mitigation pathways.
• The Talanoa Dialogue (2018): In accordance with the approach to the dialogue, this report will serve as an input. A dedicated space will be provided, both during the preparatory and the political phase, to facilitate the understanding of the implications of the report.
• The Global Stocktake (GST): In accordance with Article 14.1 of the Paris Agreement, the Conference of the Parties serving as the meeting of the Parties to the Paris Agreement (CMA) shall periodically take stock of the implementation of the Agreement to assess the collective progress towards achieving its purpose and long-term goals. It is mandated to do so in the light of, inter alia, the best available science. COP 21 agreed that each GST will be informed by “the latest reports of the IPCC” (decision 1/CP.21, paragraph 99b). COP 21 requested the SBSTA to provide advice on how the assessments of the IPCC can inform the GST. The SBSTA acknowledged that the products of the IPCC assessment cycles will be key inputs to the GST and will provide the best available scientific knowledge that is policy-relevant but not policy-prescriptive, providing an integrated scientific, technical and socioeconomic perspective. It also noted that the forthcoming products of the sixth IPCC assessment cycle will be key inputs to the first global stocktake in 2023.
   It advised that:
  • Lessons can be learned from past experience (referencing in particular, the activities relating to the 2013–2015 review, taking into account successes and shortcomings);
  • Dialogue between IPCC experts and Parties on the findings of the IPCC products, enabling a focused scientific and technical exchange of information in an open and transparent manner, could be utilized;
  • Convening special events, similar to the SBSTA–IPCC special event organized by the SBSTA (held on 18 May 2016), could be of value;
  • Views emerging from the rich exchange of information between the IPCC and Parties at the SBSTA–IPCC special event could be further considered;
  • Inputs from the IPCC should be considered in an effective and balanced manner, as part of the overall input to the global stocktake;
  • The SBSTA–IPCC Joint Working Group could be used to enhance communication and coordination between the SBSTA and the IPCC in the context of the GST.

• For more details, please see the SBSTA 45 report, paragraphs 47-56.

The special report was prepared by all three of the IPCC Working Groups: Working Group I (The Physical Science Basis), Working Group II (Impacts, Adaptation and Vulnerability) and Working Group III (Mitigation of Climate Change) – with support from the Working Group I Technical Support Unit.

List of Authors and Review Editors

• 91 authors from 44 citizenships and 40 countries of residence
• 14 Coordinating Lead Authors (CLAs)
• 60 Lead authors (LAs)
• 17 Review Editors (REs)
• 133 Contributing authors (CAs)
• Over 6,000 cited references
• A total of 42,001 expert and government review comments (First Order Draft 12,895; Second Order Draft 25,476; Final Government Draft: 3,630)

The headline statements from the SPM can be found on the IPCC webpage. They address:

A. Understanding Global Warming of 1.5°C

B. Projected Climate Change, Potential Impacts and Associated Risks

C. Emission Pathways and System Transitions Consistent with 1.5°C Global Warming

D. Strengthening the Global Response in the Context of Sustainable Development and Efforts to Eradicate Poverty