Extending Near‐Term Emissions Scenarios to Assess Warming Implications of Paris Agreement NDCs. Issue 9 (17th September 2018)

• Record Type: Journal Article
• Authors: Gütschow, Johannes; Jeffery, Mairi Louise; Schaeffer, Michiel; Hare, Bill
• Is Part Of: Earth's future. Volume 6:Issue 9(2018)
• Page Start: 1242
• Page End: 1259
• Publication Date: 2018-09-17
• Subjects: climate change -- Paris Agreement; Environmental sciences -- Periodicals; Environmental sciences; Periodicals; 550
• DOI: 10.1002/2017EF000781
• Languages: English
• ISSNs: 2328-4277

Abstract

Abstract : In the Paris Agreement countries have agreed to act together to hold global warming well below 2°C over preindustrial levels and to pursue efforts to limit warming to 1.5°C. To assess if the world is on track to meet this long‐term temperature goal, countries' pledged emissions reductions (Nationally Determined Contributions, NDCs) need to be analyzed for their implied warming. Several research groups and nongovernmental organizations have estimated this warming and arrived at very different results but have invariably concluded that the current pledges are inadequate to hold warming below 2°C, let alone 1.5°C. In this paper we analyze different methods to estimate 2100 global mean temperature rise implied by countries' NDCs, which often only specify commitments until 2030. We present different methods to extend near‐term emissions pathways that have been developed by the authors or used by different research groups and nongovernmental organizations to estimate 21st century warming consequences of Paris Agreement commitments. The abilities of these methods to project both low and high warming scenarios in line with the scenario literature is assessed. We find that the simpler methods are not suitable for temperature projections while more complex methods can produce results consistent with the energy and economic scenario literature. We further find that some methods can have a strong high or low temperature bias depending on parameter choices. The choice of methods to evaluate the consistency of aggregated NDC commitments is very important for reviewing progress toward the Paris Agreement's long‐term temperature goal. Key Points: Several methods to project 2100 temperature rise from countries' climate commitments are introduced and analyzed Simple methods can neither reproduce the scenario literature nor assess if emissions reduction pledges are 2°C consistent Scenario database‐based methods can reproduce literature ranges and be suitable for the assessment of Paris Agreement commitments