IPCC Special Report on Global Warming of 1.5 °C

IPCC Special Report on Global Warming of 1.5 °C
Name	IPCC Special Report on Global Warming of 1.5 °C
Author	Intergovernmental Panel on Climate Change
Language	English
Published	2018

IPCC Special Report on Global Warming of 1.5 °C is a 2018 scientific assessment produced by the Intergovernmental Panel on Climate Change that evaluated global pathways, impacts, risks, and responses associated with limiting global warming to 1.5 °C above pre-industrial levels. Commissioned in response to the Paris Agreement and requests from the United Nations Framework Convention on Climate Change and national parties such as the European Union and Small Island Developing States, the report synthesized evidence from climate modelling studies, sectoral literature, and policy analyses. Lead authors and contributing institutions included experts from the National Aeronautics and Space Administration, Met Office, Potsdam Institute for Climate Impact Research, University of Oxford, and Tsinghua University.

Background and Production

The report was prepared by the Intergovernmental Panel on Climate Change under the leadership of a multi-national bureau chaired by scientists with affiliations to institutions such as University of Cambridge, University of Tokyo, Massachusetts Institute of Technology, and Imperial College London. Mandated after the Paris Agreement negotiation process and decisions at the United Nations Framework Convention on Climate Change Conference of the Parties, drafting drew on assessments from the Working Group I, Working Group II, and Working Group III reports and the IPCC Fifth Assessment Report corpus. Review stages incorporated expert reviewers from World Meteorological Organization, United Nations Environment Programme, World Bank, and national academies including the Royal Society and National Academy of Sciences (United States). The summary for policymakers was approved line-by-line at a plenary session attended by delegations from United States, China, India, Brazil, and South Africa.

Key Findings

The assessment concluded that overshoot risks, carbon budget estimates, and adaptation limits significantly differ between 1.5 °C and 2 °C scenarios, drawing on evidence from studies by Intergovernmental Panel on Climate Change authors and modelling groups such as IPSL, HadGEM, GFDL, and CMIP5. It quantified remaining carbon budgets consistent with pathways to 1.5 °C referenced against studies by Global Carbon Project and International Energy Agency. The report highlighted threats to systems evaluated in literature from Food and Agriculture Organization, World Health Organization, and International Union for Conservation of Nature, noting that impacts on coral reefs documented by researchers from James Cook University and Scripps Institution of Oceanography are substantially more severe at 2 °C. The assessment emphasized the role of rapid, far-reaching transitions across energy systems studied by groups at Rocky Mountain Institute and Lawrence Berkeley National Laboratory.

Climate Pathways and Scenarios

Pathways analysed included mitigation and net-zero trajectories developed by modelling teams at International Institute for Applied Systems Analysis, Potsdam Institute for Climate Impact Research, Energy Modelling Forum, and RISE Research. Scenarios relied on integrated assessment models such as MESSAGE, REMIND, AIM/CGE, and GCAM to represent emissions trajectories, carbon dioxide removal studied by Carnegie Institution for Science teams, and afforestation strategies referenced in work by CIFOR. The report distinguished between low overshoot, high overshoot, and immediate-decarbonization pathways, drawing on scenario databases curated by IIASA and IPCC chapter authors.

Impacts and Risks at 1.5 °C vs 2 °C

Comparative analysis drew on regional assessments and case studies implemented by groups including Intergovernmental Oceanographic Commission, UNESCO, World Resources Institute, and universities such as University of Cape Town and University of the Philippines. Projected differences included greater loss of Arctic sea ice observed by National Snow and Ice Data Center, more frequent extreme heat events documented in studies from Columbia University and University of California, Berkeley, and elevated sea level rise risks impacting territories like Maldives and Tuvalu reported by UNESCO and Secretariat of the Pacific Regional Environment Programme. Biodiversity impacts cited work by IPBES, Smithsonian Institution, and Kew Gardens showing disproportionate species loss and ecosystem tipping points at higher warming levels.

Mitigation Strategies and Emissions Pathways

The report evaluated mitigation options across energy, land, and industry sectors with evidence from International Energy Agency, IRENA, BP, Shell, and university research at Stanford University. Strategies included rapid deployment of renewables, efficiency measures, electrification of transport linked to studies by European Environment Agency and California Air Resources Board, and carbon dioxide removal options such as bioenergy with carbon capture and storage researched at NETL and Drax Group. The analysis addressed technology readiness and scalability, referencing public–private initiatives like Mission Innovation and policy instruments discussed in reports by Organisation for Economic Co-operation and Development and World Bank.

Socioeconomic Dimensions and Equity

Socioeconomic pathways examined distributional outcomes using methodologies from Sustainable Development Solutions Network, Oxfam International, and International Labour Organization. Equity considerations referenced commitments under the Paris Agreement and inputs from delegations representing Least Developed Countries, African Union, and Alliance of Small Island States. The report highlighted the role of finance mechanisms involving Green Climate Fund, Global Environment Facility, and multilateral development banks such as the Asian Development Bank and European Investment Bank to support just transitions examined in case studies from Germany, China, and Costa Rica.

Reception, Influence, and Policy Response

Following publication, the assessment influenced policy discussions at Conference of the Parties 24, Conference of the Parties 25, and national strategies in jurisdictions including European Union, United Kingdom, Canada, New Zealand, and Chile. Scientific and civil society actors from Extinction Rebellion, 350.org, and World Wildlife Fund used the findings to advocate for accelerated action, while industry stakeholders including Shell plc and BP plc referenced scenario analyses in corporate strategies. The report informed updates to nationally determined contributions submitted to the United Nations Framework Convention on Climate Change and catalysed legislation such as net-zero targets in parliaments of United Kingdom and European Union member states. Category:Climate change reports