Research Guides: Climate Change: Reports

The Congressional Research Service (CRS) is a legislative branch agency located within the Library of Congress. Members of the CRS work for Congress providing objective and authoritative research and analysis on any topic of interest or related to Congressional activities. CRS Reports are designed to help members of Congress perform their legislative role.

The Intergovernmental Panel on Climate Change (IPCC) is a body of the United Nations responsible for assessing the science related to climate change. The IPCC was created in 1988 by the World Meteorological Organization (WMO) and the United Nations Program for the Environment (UNEP) in order to provide all governments with scientific information that can be used to develop policies related to climate change. The IPCC does not conduct its own research, but through expert review and analysis it assess the scientific research that exists in the world.

The IPCC is divided into three Working Groups and a Task Force. Working Group I addresses the physical science of climate change. Working Group II is responsible for climate change impacts, adaptation, and vulnerability. Working Group III addresses climate change mitigation. The Task Force on National Greenhouse Gas Inventories develops and refines the methodology for calculating and reporting national greenhouse gas emissions and removals. In March 2018, the IPCC decided to establish a Task Group to improve gender balance and address gender-related issues within the IPCC.

Assessment Report 1: Scientific Assessment of Climate Change
Report of Working Group I outlining how human activities may be changing the climate through greenhouse gas emissions. Issued June 1990.
Assessment Report 1: Impacts Assessment of Climate Change
Report of Working Group II assessing the physical and biological impacts of climate change. Issued July 1990.
Assessment Report 1: The IPC Response Strategies
Report of Working Group III, which identifies and evaluates possible strategies for limiting or adapting to climate change. Issued in October 1990.
Assessment Report 2: The Science of Climate Change
Report of Working Group I, updating information from the first report issued in 1990. Recognized the increase of greenhouse gas concentrations, the change of the earth's climate over the past one hundred years, human influence on climate, and expected continued climate change. Issued February 1995.
Assessment Report 2: Impacts, Adaptations, and Mitigation of Climate Change: Scientific-Technical Analyses
Report of Working Group II focusing on possible responses to climate change and measures that could be taken to limit future emissions. Issued July1995.
Assessment Report 2: Economic and Social Dimensions of Climate Change
Report from Working Group III discussing equity issues, cost and benefit assessments related to climate change, social costs of climate change, estimation of mitigation costs, responses to climate change, and assessment of policy considerations. Issued July 1995.
Assessment Report 2: Synthesis Report
Issued October 1995.
IPCC Second Assessment Full Report
Issued in June 1996. Available in English, Arabic, Chinese, French, Russian, and Spanish.
TAR Climate Change 2001: The Scientific Basis
Third Assessment Report from Working Group I analyzing observations from around the climate system, projecting future climate scenarios, studying if human influence on climate can be identified, and suggesting gaps in information. Issued January 2001.
TAR Climate Change 2001: Impacts, Adaptation, and Vulnerability
Third Assessment Report of Working Group II detailing the vulnerabilities of humans to future climate change including rising sea levels, climate extremes, water and food security, and human health. Also discusses potential responses of wildlife and natural environments and how adaptation may lessen impacts of climate change. Vulnerabilities in different areas of the world are addressed. Issued May 2001.
TAR Climate Change 2001: Mitigation
Third Assessment Report of Working Group III assessing scientific, technical, economic, and social aspects of mitigation of climate change. Issued July 2001.
TAR Climate Change 2001: Synthesis Report
Issued October 2001.
Assessment Report 4 Climate Change 2007: The Physical Science Basis
Report of Working Group I assessing the physical science of climate change including new data sets, analyses, and modeling. Issued June 2007.
Assessment Report 4 Climate Change 2007: Impacts, Adaptation, and Vulnerability
Report of Working Group II assessing future impacts of climate change, detailing changes in climate that have already affected physical and biological systems, evaluating key vulnerabilities, and discussing the trade offs of mitigation and adaptation. Issued July 2007.
Assessment Report 4 Climate Change 2007: Mitigation of Climate Change
Report of Working Group III analyzing the costs and benefits of approaches to mitigating climate change. Issued June 2007.
Assessment Report 4 Climate Change 2007: Synthesis Report
Issued September 2007.
Assessment Report 5 Climate Change 2013: The Physical Science Basis
Report of Working Group I including near-term projections and predictability as well as long-term projections and irreversibility. Issued September 2013.
Assessment Report 5 Climate Change 2014: Impacts, Adaptation, and Vulnerability
Report of Working Group II discussing regional issues as well as global-scale issues. Issued March 2014.
Assessment Report 5 Climate Change 2014: Mitigation of Climate Change
Report of Working Group III highlighting the acceleration of GHG emissions despite increase in mitigation policies. Reviews the 2 degrees Celsius goal as well as the 1.5 degrees Celsius goal of the UNFCCC. Issued April 2014.
Assessment Report 5 Climate Change 2014: Synthesis Report
Issued October 2014.
Assessment Report 6: Climate Change 2021: The Physical Science Basis
Finalized Aug. 6, 2021 by Working Group I.
Assessment Report 6: Climate Change 2022: Impacts, Adaptation and Vulnerability
Issued Feb. 27, 2022 by Working Group II.
Assessment Report 6: Climate Change 2022: Mitigation of Climate Change
Issued Apr. 4, 2022 by Working Group III.
Assessment Report 6: Synthesis Report: Climate Change 2022
September 2022.

Ocean and Cryosphere in a Changing Climate
Special report presented September 2019 detailing the shrinking of the cryosphere caused by loss of ice sheets and glaciers, increase in global ocean temperatures and global sea level, and loss of sea life.
Climate Change and Land
A special report issued in August 2019 on climate change, desertification, land degradation, land management, food security, and greenhouse gas fluxes.
Global Warming of 1.5 degrees Celsius
A special report issued by the IPCC relating to the impacts of global warming 1.5 degrees Celsius above pre-industrial levels. Issued October 2018.
Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation
Issued March 2012.
Renewable Energy Sources and Climate Change Mitigation
Analyzes and assesses renewable energy technologies including current and future roles in climate change mitigation. Issued April 2011.
Safeguarding the Ozone Layer and the Global Climate System
Developed in response to the UNFCCC and Montreal Protocol. Issued March 2005.
Carbon Dioxide Capture and Storage
Discusses the costs, economic potential, social issues, regulatory issues, and technological issues related to carbon capture and storage. Issued March 2005.
Methodological and Technological Issues in Technology Transfer
Discusses types of transfer, sectors targeted, the role of participants, promoting cooperation, and capacity building. Issued March 2000.
Land Use, Land Use Change, and Forestry
Discusses the global carbon cycle and how land use and forestry effect carbon stocks and GHG emissions. Issued March 2000.
Emissions Scenarios
Looks at the future and predicts GHG emissions related to possible future actions. Issued March 2000.
Aviation and the Global Atmosphere
Report prepared at the request of the International Civil Aviation Organization (ICAO) and Parties to the Montreal Protocol to understand the effects aviation has had and potential effects it may have on stratospheric ozone depletion and climate change around the globe. Issued March 1999.
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Only the Summary for Policymakers is available at this time.
The Regional Impacts of Climate Change: An Assessment of Vulnerability
Special Report issued by Working Group II in response to a request from the Subsidiary Body for Scientific and Technical Advice (SBSTA) of the UNFCCC. The report addresses the extent to which human activities and the environment are vulnerable to climate change. Assessed the vulnerability of 10 different regions around the globe. Issued March 1997.
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Only the Summary for Policymakers is available at this time.
Climate Change 1994: Radiative Forcing of of Climate Change and An Evaluation of the IPCC IS92 Emission Scenarios
A special report issued prior to the first Conference of the Parties. Issued March 1994.
IPCC Technical Guidelines for Assessing Climate Change Impacts and Adaptations
Prepared by Working Group II to provide guidelines for assessing the impacts of climate change and evaluate appropriate adaptations. Issued March 1994.
Climate Change 1992: The Supplementary Report to the IPCC Scientific Assessment
Update to the 1990 first reports prepared to assist with the ongoing negotiations of the UNFCCC. Issued June 1992.
Climate Change 1992: The Supplementary Report to the IPCC Impacts Assessment
Update to the 1990 first reports prepared to assist with the ongoing negotiations of the UNFCCC. Issued June 1992.
Climate Change: The IPCC 1990 and 1992 Assessments
Prepared to assist with the ongoing negotiations of the UNFCC. Issued April 1992

The U.S. Global Change Research Act of 1990 provides for the U.S. Global Change Research Program to provide a report to Congress and the President no less than every 4 years. Such report is meant to integrate, evaluate, and interpret the findings of the Program; analyze the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, health and welfare, social systems, and biological diversity; and analyze the current trends in global change caused by humans and nature and project trends for the coming 25 to 100 years.

Fourth National climate Assessment: Volume I
Issued under the requirements of the Global Change Research Act of 1990, this report is an authoritative assessment of the science of climate change intended to serve as a foundation for climate risk assessments and responses. Policy recommendations are not included. The focus of the assessment is on the United States. Issued in 2017.
Fourth National Climate Assessment: Volume II
This volume uses the science discussed in Volume I in order to focus on observed and projected risks, impacts, and mitigation options across 10 regions of the United States. Examples of actions being used in different communities is included. Issued in November 2018.
Third National Climate Assessment
Issued in 2014.
Second National Climate Assessment
Issued in 2009.
First National Climate Assessment
Issued in 2000.

The Global Environment Outlook (GEO) is published by the United Nations Environment Programme. The program was first launched in 1995 and brought together scientists, peer reviewers, and other partners to outline the current state of environment, highlight possible future trends, and analyze the effectiveness of policies.

GEO 6
Published in 2019 with the goal of providing information to propel the globe to a sustainable world by 2050.
GEO 5
Published in 2012.
GEO 4
Published in 2007. Focused on sustainable development.
GEO 3
Published in 2002 for the World Summit on Sustainable Development in South Africa.
GEO 2000
Published in 1999.
GEO 1
First report published in 1997.

Arctic Report Card
NOAA has issued the Arctic Report Card annually since 2006. It is a peer-reviewed source of environmental information on the current state of Arctic environmental components relative to available historical records.
Living Planet Report
Report issued by the World Wildlife Fund every 2 years, which discusses trends in global biodiversity and the health of the planet.
Production Gap Report
First issued in 2019, this report tracks the discrepancy between governments' planned fossil fuel production and global production levels that would be consistent with limiting warming by 1.5 or 2 degrees Celsius.
State of the Global Climate 2021
Report from the World Meteorological Organization that summarizes the state of climate indicators in 2021.
United in Science 2022
Report from the World Meteorological Organization in connection with the UN that compiled the latest science related to climate change impacts and responses.