Sixth Assessment Report

Sixth Assessment Report
Title	Sixth Assessment Report
Author	Intergovernmental Panel on Climate Change
Country	Multinational
Language	English
Subject	Climate change
Publisher	Intergovernmental Panel on Climate Change
Pub date	2021–2023

Sixth Assessment Report The Sixth Assessment Report is a comprehensive scientific assessment produced by the Intergovernmental Panel on Climate Change between 2021 and 2023 that synthesizes research from the United Nations Framework Convention on Climate Change, World Meteorological Organization, European Commission, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, and numerous national academies including the Royal Society and the US National Academy of Sciences. It builds on previous assessments such as the Fifth Assessment Report and incorporates evidence from studies published in journals like Nature, Science, and Proceedings of the National Academy of Sciences to inform international processes including the Paris Agreement, United Nations Climate Change Conference, and national climate strategies.

Overview

The report, coordinated by the Intergovernmental Panel on Climate Change, involved authors from institutions like University of Oxford, Massachusetts Institute of Technology, Tsinghua University, University of Tokyo, and Australian National University and was overseen by working groups linked to bodies including the World Health Organization, Food and Agriculture Organization, and International Energy Agency. It integrates observational datasets from sources such as HadCRUT, NOAA National Centers for Environmental Information, Copernicus Programme, and Global Carbon Project and projects future scenarios used by stakeholders including the European Union, G20, United States, China, and India.

Structure and Content

The assessment is organized into three Working Group reports and a Synthesis Report, with contributions from convening lead authors affiliated with Columbia University, Imperial College London, University of California, Berkeley, Peking University, and McGill University. Working Group I focuses on physical science foundations drawing on paleoclimate reconstructions such as the Greenland ice cores and Antarctic ice cores and satellite records from Landsat and Sentinel. Working Group II addresses impacts, adaptation, and vulnerability with case studies involving the Amazon Rainforest, Great Barrier Reef, Sahara Desert, and island states like Tuvalu and Maldives. Working Group III examines mitigation pathways and includes scenarios from Shared Socioeconomic Pathways, integrated assessment models used by International Energy Agency and Organisation for Economic Co-operation and Development, and mitigation technologies linked to institutions like International Renewable Energy Agency and companies in the Global Wind Energy Council.

Key Findings

The report concluded that recent changes in the climate system are widespread, rapid, and intensifying, supported by evidence from instrumental records compiled by Met Office Hadley Centre, NOAA, and Japan Meteorological Agency and by attribution studies involving teams from Harvard University, University of Cambridge, and ETH Zurich. It finds human influence from activities in sectors such as fossil fuel extraction in regions including Persian Gulf, Appalachian Basin, and Siberia has unequivocally warmed the atmosphere, oceans, and cryosphere, accelerating sea level rise affecting coastlines from Bangladesh to Netherlands and island nations like Kiribati. The assessment quantifies risks to food systems in river basins such as the Mekong River, Nile River, and Amazon River and projects increased extreme events documented in case studies on the California wildfires, European heatwaves, and Australian bushfires. Mitigation pathways compatible with limiting warming to 1.5 °C or 2 °C rely on rapid deployment of low-carbon technologies exemplified by projects at Iberdrola, Siemens Gamesa, and Ørsted and policy mechanisms debated at United Nations General Assembly and G20 Summit.

Impacts and Policy Responses

Policy responses informed by the report have influenced nationally determined contributions submitted to the Paris Agreement and investment strategies by multilateral banks such as the World Bank and Asian Development Bank and by private actors including BlackRock and Goldman Sachs. Adaptation measures cited involve urban planning in cities like New York City, Mumbai, and Lagos; coastal defenses in Venice and Rotterdam; and agricultural shifts in regions such as Punjab (India), California Central Valley, and Andalusia. International diplomatic activities reacting to the report occurred at meetings of the Conference of the Parties and in forums including the G7 Summit and BRICS Summit where mitigation finance, loss and damage, and technology transfer were negotiated.

Reception and Criticism

The report received endorsements from scientific bodies including the American Geophysical Union, European Geosciences Union, and Royal Society of Canada, and spurred commentary in media outlets such as The New York Times, The Guardian, and Le Monde. Critics from political actors in parliaments such as the United States Senate and the House of Commons and industry groups like National Mining Association and U.S. Chamber of Commerce raised disputes over socioeconomic assumptions in integrated assessment models developed by teams at IIASA and Potsdam Institute for Climate Impact Research. Scholarly critiques focused on uncertainties in regional projections affecting stakeholders in places like Sahel and Himalayas and on treatment of carbon dioxide removal technologies debated by researchers at Carnegie Institution for Science and Rocky Mountain Institute.

History and Development Process

The assessment cycle was initiated by the Intergovernmental Panel on Climate Change following approval at plenary sessions attended by delegates from United Nations, World Meteorological Organization, and member states including United Kingdom, United States, China, Russia, Brazil, and South Africa. The development process involved scoping led by experts from IPBES, International Maritime Organization, and World Bank and multiple rounds of expert and government review with participation from institutions such as National Science Foundation, European Research Council, and Academia Sinica. Lead authorship and review incorporated contributions from academics affiliated with Yale University, University of Nairobi, Universidad Nacional Autónoma de México, and University of Cape Town culminating in approval sessions in venues including Geneva and Bonn.

Category:Climate reports