IPCC Sixth Assessment Report

IPCC Sixth Assessment Report
Name	IPCC Sixth Assessment Report
Title	Climate Change 2021: The Physical Science Basis, Climate Change 2022: Impacts, Adaptation and Vulnerability, Climate Change 2022: Mitigation of Climate Change, Climate Change 2023: Synthesis Report
Date	2021–2023
Publisher	Intergovernmental Panel on Climate Change

IPCC Sixth Assessment Report. The Sixth Assessment Report (AR6) is the latest comprehensive evaluation of climate change science from the Intergovernmental Panel on Climate Change, published between 2021 and 2023. It consolidates findings from thousands of scientific studies to inform international climate policy, notably for the Paris Agreement global stocktake. The assessment provides critical updates on the physical science, impacts, and mitigation pathways, representing a consensus of the world's leading climate scientists.

Overview

The AR6 cycle was approved by the IPCC during its 41st Session in Nairobi in 2015, following the completion of the IPCC Fifth Assessment Report. The work was structured around the three established IPCC Working Groups and a dedicated Task Force on National Greenhouse Gas Inventories. Key preparatory meetings and approval plenaries were held in locations including Incheon, Geneva, and Interlaken, with the final synthesis report released ahead of the first Global Stocktake under the United Nations Framework Convention on Climate Change. The assessment integrates advances in climate science since the IPCC Special Report on Global Warming of 1.5 °C and the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate.

Working Groups and Reports

The physical science basis was addressed by Working Group I, whose report "Climate Change 2021: The Physical Science Basis" was finalized and approved in plenary in August 2021. Working Group II assessed impacts, adaptation, and vulnerability, publishing its findings in "Climate Change 2022: Impacts, Adaptation and Vulnerability" following a plenary in February 2022. Concurrently, Working Group III analyzed mitigation of climate change, releasing "Climate Change 2022: Mitigation of Climate Change" after a plenary in April 2022. The Task Force on National Greenhouse Gas Inventories updated its 2019 Refinement to the 2006 IPCC Guidelines. All working group reports underwent extensive review by experts and governments, a process overseen by the IPCC Bureau.

Key Findings

The AR6 concluded that human influence has unequivocally warmed the atmosphere, ocean, and land, with widespread and rapid changes observed. It presented updated climate model projections using Shared Socioeconomic Pathways, narrowing the range of climate sensitivity. The report stated that limiting warming to 1.5°C above pre-industrial levels, as per the Paris Agreement, is barely achievable without immediate and deep reductions in emissions of carbon dioxide, methane, and other greenhouse gases. It detailed increasing risks from sea level rise, extreme weather, and biodiversity loss, with disproportionate impacts on vulnerable regions like Africa, Asia, and Small Island Developing States. The assessment emphasized that adaptation options are limited if warming exceeds 1.5°C.

Synthesis Report

The "Climate Change 2023: Synthesis Report" integrates the core findings from the three working group reports. Approved in Interlaken in March 2023, it provides a high-level summary for policymakers. The synthesis underscores the closing window for securing a livable future, outlining feasible and effective mitigation and adaptation strategies across all sectors and systems. It frames climate action within the context of sustainable development and equity, informing the Global Stocktake process at the 2023 United Nations Climate Change Conference in Dubai.

Reception and Impact

The AR6 has been widely cited by governments, the United Nations, and civil society organizations like the World Resources Institute. Its stark warnings influenced discussions at the 2021 United Nations Climate Change Conference in Glasgow and subsequent Conference of the Parties meetings. The findings have been instrumental in legal contexts, including submissions to the International Court of Justice and cases brought by groups like ClientEarth. Media coverage by outlets such as The Guardian and BBC News highlighted the report's urgent tone. Criticisms, often from groups like the Global Warming Policy Foundation, focused on economic implications, but the scientific consensus represented by the AR6 remains overwhelmingly accepted by bodies like the World Meteorological Organization.

Authors and Process

The report was authored by hundreds of scientists from over 60 countries, nominated by IPCC member governments and observer organizations. The writing teams were coordinated by Working Group co-chairs, including Valérie Masson-Delmotte and Panmao Zhai for Working Group I. The process involved multiple stages of draft composition and review, receiving over 78,000 expert and government comments. The author teams, operating under strict IPCC principles and procedures, assessed thousands of scientific papers, with all conclusions subject to line-by-line approval by member government representatives in plenary sessions. The IPCC Secretariat, based in Geneva, provided logistical and technical support throughout the multi-year assessment.

Category:Intergovernmental Panel on Climate Change reports Category:2021 in the environment Category:2022 in the environment Category:2023 in the environment