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Climate Change 2014 Synthesis Report

Edited by

The Core Writing Team

Synthesis Report IPCC

Rajendra K. Pachauri

Chairman IPCC

Leo Meyer

Head, Technical Support Unit IPCC

Core Writing Team Rajendra K. Pachauri (Chair), Myles R. Allen (United Kingdom), Vicente R. Barros (Argentina), John Broome (United Kingdom), Wolfgang Cramer (Germany/France), Renate Christ (Austria/WMO), John A. Church (Australia), Leon Clarke (USA), Qin Dahe (China), Purnamita Dasgupta (India), Navroz K. Dubash (India), Ottmar Edenhofer (Germany), Ismail Elgizouli (Sudan), Christopher B. Field (USA), Piers Forster (United Kingdom), Pierre Friedlingstein (United Kingdom/Belgium), Jan Fuglestvedt (Norway), Luis Gomez-Echeverri (Colombia), Stephane Hallegatte (France/World Bank), Gabriele Hegerl (United Kingdom/Germany), Mark Howden (Australia), Kejun Jiang (China), Blanca Jimenez Cisneros (Mexico/UNESCO), Vladimir Kattsov (Russian Federation), Hoesung Lee (Republic of Korea), Katharine J. Mach (USA), Jochem Marotzke (Germany), Michael D. Mastrandrea (USA), Leo Meyer (The Netherlands), Jan Minx (Germany), Yacob Mulugetta (Ethiopia), Karen O’Brien (Norway), Michael Oppenheimer (USA), Joy J. Pereira (Malaysia), Ramón Pichs-Madruga (Cuba), Gian-Kasper Plattner (Switzerland), Hans-Otto Pörtner (Germany), Scott B. Power (Australia), Benjamin Preston (USA), N.H. Ravindranath (India), Andy Reisinger (New Zealand), Keywan Riahi (Austria), Matilde Rusticucci (Argentina), Robert Scholes (South Africa), Kristin Seyboth (USA), Youba Sokona (Mali), Robert Stavins (USA), Thomas F. Stocker (Switzerland), Petra Tschakert (USA), Detlef van Vuuren (The Netherlands), Jean-Pascal van Ypersele (Belgium)

Technical Support Unit for the Synthesis Report Leo Meyer, Sander Brinkman, Line van Kesteren, Noëmie Leprince-Ringuet, Fijke van Boxmeer

Referencing this report IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, I and II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 p.

THE INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE © Intergovernmental Panel on Climate Change, 2015 First published 2015 ISBN 978-92-9169-143-2

This publication is identical to the report that was approved (Summary for Policymakers) and adopted (longer report) at the 40th session of the Intergovernmental Panel on Climate Change (IPCC) on 1 November 2014 in Copenhagen, Denmark, but with the inclusion of copy-edits and errata that have been corrected prior to this publication. These pre-publication errata are available at: http://www.ipcc.ch

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Cover: Design by Laura Biagioni, IPCC Secretariat, WMO Photos:

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Foreword, Preface and Dedication

F or ewor


The Synthesis Report (SYR) distils and integrates the findings of the three Working Group contributions to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), the most comprehensive assessment of climate change undertaken thus far by the IPCC: Climate Change 2013: The Physical Science Basis; Climate Change 2014: Impacts, Adaptation, and Vulnerability; and Climate Change 2014: Mitigation of Climate Change. The SYR also incorporates the findings of two Special Reports on Renewable Energy Sources and Climate Change Mitigation (2011) and on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (2011).

The SYR confirms that human influence on the climate system is clear and growing, with impacts observed across all continents and oceans. Many of the observed changes since the 1950s are unprecedented over decades to millennia. The IPCC is now 95 percent certain that humans are the main cause of current global warming. In addition, the SYR finds that the more human activities disrupt the climate, the greater the risks of severe, pervasive and irreversible impacts for people and ecosystems, and long-lasting changes in all components of the climate system. The SYR highlights that we have the means to limit climate change and its risks, with many solutions that allow for continued economic and human development. However, stabilizing temperature increase to below 2°C relative to pre-industrial levels will require an urgent and fundamental departure from business as usual. Moreover, the longer we wait to take action, the more it will cost and the greater the technological, economic, social and institutional challenges we will face.

These and the other findings of the SYR have undoubtedly and considerably enhanced our understanding of some of the most critical issues in relation to climate change: the role of greenhouse gas emissions; the severity of potential risks and impacts, especially for the least developed countries and vulnerable communities, given their limited ability to cope; and the options available to us and their underlying requirements to ensure that the effects of climate change remain manageable. As such, the SYR calls for the urgent attention of both policymakers and citizens of the world to tackle this challenge.

The timing of the SYR, which was released on 2nd November 2014 in Copenhagen, was crucial. Policymakers met in December 2014 in Lima at the 20th Conference of Parties under the United Nations Framework Convention on Climate Change (UNFCCC) to prepare the groundwork for the 21st Session in 2015 in Paris, when they have been tasked with concluding a new agreement to deal with climate change. It is our hope that the scientific findings of the SYR will be the basis of their motivation to find the way to a global agreement which can keep climate change to a manageable level, as the SYR gives us the knowledge to make informed choices, and enhances our vital understanding of the rationale for action – and the serious implications of inaction. Ignorance can no longer be an excuse for tergiversation.

As an intergovernmental body jointly established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), the Intergovernmental Panel on Climate Change (IPCC) has provided policymakers with the most authoritative and objective scientific and technical assessments in this field. Beginning in 1990, this series of IPCC Assessment Reports, Special Reports, Technical Papers, Methodology Reports and other products have become standard works of reference.

The SYR was made possible thanks to the voluntary work, dedication and commitment of thousands of experts and scientists from around the globe, representing a range of views and disciplines. We would like to express our deep gratitude to all the members of the Core Writing Team of the SYR, members of the Extended Writing Team, and the Review Editors, all of whom enthusiastically took on the huge challenge of producing an outstanding SYR on top of the other tasks they had already committed to during the AR5 cycle. We would also like to thank the staff of the Technical Support Unit of the SYR and the IPCC Secretariat for their dedication in organizing the production of this IPCC report.

We also wish to acknowledge and thank the governments of the IPCC member countries for their support of scientists in developing this report, and for their contributions to the IPCC Trust Fund to provide the essentials for participation of experts from developing countries and countries with economies in transition. We would like to express our appreciation to the government of Wallonia (Belgium) for hosting the Scoping Meeting of the SYR, to the governments of Norway, the Netherlands, Germany and Malaysia for hosting drafting sessions of the SYR, and to the government of Denmark for hosting the 40th Session of the IPCC where the SYR was approved. The generous financial support from the governments of Norway and the Netherlands, from the Korea Energy Economics Institute, and the in-kind support by the Netherlands Environmental Assessment Agency and The Energy and Resources Institute, New Delhi (India), enabled the smooth operation of the Technical Support Unit of the SYR. This is gratefully acknowledged.

We would particularly like to express our thanks to Dr Rajendra K. Pachauri, Chairman of the IPCC, for his leadership and constant guidance throughout the production of this report.

Michel Jarraud Secretary General World Meteorological Organization

Achim Steiner Executive Director United Nations Environmental Programme vii

Pr eface


The Synthesis Report (SYR), constituting the final product of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), is published under the title Climate Change 2014. This report distils, synthesizes and integrates the key findings of the three Working Group contributions – The Physical Science Basis, Impacts, Adaptation, and Vulnerability and Mitigation of Climate Change – to the AR5 in a concise document for the benefit of decision makers in the government, the private sector as well as the public at large. The SYR also draws on the findings of the two Special Reports brought out in 2011 dealing with Renewable Energy Sources and Climate Change Mitigation, and Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. The SYR, therefore, is a compre- hensive up-to-date compilation of assessments dealing with climate change, based on the most recent scientific, technical and socio-economic literature in the field.

Scope of the Report

This document is the result of coordinated and carefully connected cross Working Group efforts to ensure coherent and comprehensive information on various aspects related to climate change. This SYR includes a consistent evaluation and assessment of uncertainties and risks; integrated costing and economic analysis; regional aspects; changes, impacts and responses related to water and earth systems, the carbon cycle including ocean acidification, cryosphere and sea level rise; as well as treatment of mitigation and adaptation options within the framework of sustainable development. Through the entire length of the SYR, information is also provided relevant to Article 2, the ultimate objective of the United Nations Framework Convention on Climate Change (UNFCCC).

Other aspects of climate change covered in this report include direct impacts of climate change on natural systems as well as both direct and indirect impacts on human systems, such as human health, food security and security of societal conditions. By embedding climate change risk and issues of adaptation and mitigation within the framework of sustainable development, the SYR also highlights the fact that nearly all systems on this planet would be affected by the impacts of a changing climate, and that it is not possible to draw boundaries around climate change, its associated risks and impacts on the one hand and on the other, development which meets the needs of the present generation without compromising the ability of future generations to meet their own needs. The Report, therefore, also focuses on connections between these aspects and provides information on how climate change overlaps with and mainstreams into other developmental issues.


The Report comprises a Summary for Policymakers (SPM) and a longer report from which the SPM is derived, as well as annexes. Even though the SPM follows a structure and sequence similar to that in the longer report, some specific issues covered under more than one topic of the longer report are summarized in one particular section of the SPM. Each paragraph of the SPM contains references to the respective text in the longer report. In turn, the latter contains extensive references to relevant chapters of the underlying Working Group Reports or the two Special Reports mentioned above. The SYR is essentially self-contained, and its SPM includes the most policy relevant material drawn from the longer report and the entire AR5.

All the three contributions to the AR5 including each Summary for Policymakers, each Technical Summary, frequently asked questions as well as the Synthesis Report in all official UN languages are available online on the IPCC website and in electronic offline versions. In these electronic versions, references in the SYR to relevant parts of the underlying material are provided as hyperlinks, thereby enabling the reader to easily find further scientific, technical and socio-economic information. A user guide, glossary of terms used and listing of acronyms, authors, Review Editors and Expert Reviewers are provided in the annexes to this report.

To facilitate access to the findings of the SYR for a wide readership and to enhance their usability for stakeholders, each section of the SPM carries highlighted headline statements. Taken together, these 21 headline statements provide an overarching summary in simple and completely non-technical language for easy assimilation by readers from different walks of life. These headline statements have been crafted by the authors of the Report, and approved by the member governments of the IPCC.

The longer report is structured around four topic headings as mandated by the Panel:

Observed changes and their causes (Topic 1) integrates new information from the three Working Groups on observed changes in the climate system, including changes in the atmosphere, oceans, cryosphere and sea level; recent and past drivers and human influences affecting emission drivers; observed impacts, including changes in extreme weather and climate events; and attribution of climate changes and impacts.

Future climate changes, risks and impacts (Topic 2) presents informa- tion about future climate change, risks and impacts. It integrates information about key drivers of future climate, the relationship between cumulative emissions and temperature change, and projected changes in the climate system in the 21st century and beyond. It assesses future risks and impacts caused by a changing climate and the interaction of climate-related and other hazards. It provides information about longterm changes including sea-level rise and ocean acidification, and the risk of irreversible and abrupt changes.

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