Chapter 13 IPCC WGI Fifth Assessment Report
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Second Order Draft Chapter 13 IPCC WGI Fifth Assessment Report 1 2 Chapter 13: Sea Level Change 3 4 Coordinating Lead Authors: John A. Church (Australia), Peter U. Clark (USA) 5 6 Lead Authors: Anny Cazenave (France), Jonathan Gregory (UK), Svetlana Jevrejeva (UK), Anders 7 Levermann (Germany), Mark Merrifield (USA), Glenn Milne (Canada), R. Steven Nerem (USA), Patrick 8 Nunn (Australia), Antony Payne (UK), W. Tad Pfeffer (USA), Detlef Stammer (Germany), Alakkat 9 Unnikrishnan (India) 10 11 Contributing Authors: David Bahr (USA), Jason E. Box (USA), David H. Bromwich (USA), Mark Carson 12 (Germany), William Collins (UK), Xavier Fettweis (Belgium), Piers Forster (UK), Alex Gardner (USA), 13 Peter Good (UK), Rune Grand Graversen (Sweden), Ralf Greve (Japan), Stephen Griffies (USA), Edward 14 Hanna (UK), Mark Hemer (Australia), Regine Hock (USA), Simon J. Holgate (UK), John Hunter 15 (Australia), Philippe Huybrechts (Belgium), Gregory Johnson (USA), Ian Joughin (USA), Georg Kaser 16 (Austria), Caroline Katsman (Netherlands), Leonard Konikow (USA), Gerhard Krinner (France), Jan 17 Lanaerts (Netherlands), Ben Marzeion (Austria), Kathleen L. McInnes (Australia), Sebastian Mernild 18 (USA), Didier Monselesan (Australia), Ruth Mottram (Denmark), Tavi Murray (UK), Gunnar Myhre 19 (Norway), J.P. Nicholas (USA), David Pollard (USA),Valentina Radić (Canada), Jamie Rae (UK), Christian 20 Schoof (Canada), Aimée Slangen (Netherlands), Jan H. van Angelen (Netherlands), Willem Jan van de Berg 21 (Netherlands), Michiel van den Broeke (Netherlands), Miren Vizcaíno (Netherlands), Yoshihide Wada 22 (Netherlands), Jianjun Yin (USA), Masakazu Yoshimori (Japan) 23 24 Review Editors: Jean Jouzel (France), Roderik van de Wal (Netherlands), Philip L. Woodworth (UK), 25 Cunde Xiao (China) 26 27 Date of Draft: 5 October 2012 28 29 Notes: TSU Compiled Version 30 31 32 Table of Contents 33 34 Executive Summary..........................................................................................................................................3 35 13.1 Components and Models of Sea Level Change......................................................................................6 36 13.1.1 Introduction and Chapter Overview ...............................................................................................6 37 13.1.2 Fundamental Definitions and Concepts..........................................................................................7 38 13.1.3 Sea Level Change Caused by Contemporary Climate Change ......................................................8 39 13.1.4 Sea Level Change Not Caused by Contemporary Climate Change................................................9 40 13.1.5 Models Used to Interpret Past and Project Future Changes in Sea Level.....................................9 41 13.2 Past Sea Level Change ...........................................................................................................................12 42 13.2.1 The Geological Record .................................................................................................................12 43 13.2.2 The Instrumental Record (~1700–2010).......................................................................................13 44 FAQ 13.1: Why Does Local Sea Level Change Differ from the Global Average? ...................................14 45 13.3 Contributions to Global Mean Sea Level Rise During the Instrumental Period .............................16 46 13.3.1 Thermosteric Contribution............................................................................................................16 47 13.3.2 Glaciers.........................................................................................................................................17 48 13.3.3 Greenland and Antarctic Ice Sheets .............................................................................................17 49 13.3.4 Contributions from Water Storage on Land .................................................................................21 50 13.3.5 Ocean Mass Observations from GRACE (2002–2010) ................................................................22 51 13.3.6 Budget of GMSL Rise....................................................................................................................23 52 Box 13.1: The Global Energy Budget ...........................................................................................................24 53 13.4 Projected Contributions to Global Mean Sea Level............................................................................26 54 13.4.1 Ocean Heat Uptake and Thermosteric Sea Level Rise .................................................................26 55 13.4.2 Glaciers.........................................................................................................................................27 56 13.4.3 Greenland Ice Sheet......................................................................................................................29 57 13.4.4 Antarctic Ice Sheet ........................................................................................................................35 Do Not Cite, Quote or Distribute 13-1 Total pages: 110 Second Order Draft Chapter 13 IPCC WGI Fifth Assessment Report 1 Box 13.2: History of the Marine Ice Sheet Instability Hypothesis .............................................................41 2 FAQ 13.2: Will the Greenland and Antarctic Ice Sheets Contribute to Sea Level Change Over the 3 Rest of the Century?...............................................................................................................................42 4 13.4.5 Anthropogenic Intervention in Water Storage on Land................................................................44 5 13.5 Projections of Global Mean Sea Level Rise .........................................................................................44 6 13.5.1 Projections for the 21st Century ...................................................................................................45 7 13.5.2 Projections Beyond the 21st Century............................................................................................51 8 13.6 Regional Sea Level Changes..................................................................................................................54 9 13.6.1 Regional Sea Level Changes, Climate Modes and Forced Sea Level Response ..........................55 10 13.6.2 CMIP5 GCM Projections/Predictions on Decadal to Centennial Time Scales ...........................55 11 13.6.3 Response to Atmospheric Pressure Changes................................................................................56 12 13.6.4 Response to Freshwater Forcing ..................................................................................................57 13 13.6.5 Net Regional Sea Level Changes ..................................................................................................58 14 13.6.6 Uncertainties and Sensitivity to Ocean/Climate Model Formulations and Parameterizations ...59 15 13.6.7 Summary Assessment ....................................................................................................................60 16 13.7 21st Century Projections of Sea Level Extremes and Waves .............................................................60 17 13.7.1 Changes in Sea Level Extremes ....................................................................................................61 18 13.7.2 Projections of Extreme Sea Levels................................................................................................61 19 13.7.3 Projections of Ocean Waves .........................................................................................................62 20 13.7.4 Summary Assessment ....................................................................................................................64 21 13.8 Synthesis and Key Uncertainties...........................................................................................................64 22 References........................................................................................................................................................66 23 Appendix 13.A: Methods of Sea Level Projections for the 21st Century..................................................83 24 Figures .............................................................................................................................................................85 25 Do Not Cite, Quote or Distribute 13-2 Total pages: 110 Second Order Draft Chapter 13 IPCC WGI Fifth Assessment Report 1 Executive Summary 2 3 Changes in sea level represent an integration of many aspects of climate change, and thus occur over a broad 4 range of temporal and spatial scales. The primary contributors to global averaged sea level change are the 5 expansion/contraction of the ocean as it warms/cools and the transfer of water to/from the ocean/land, 6 particularly from glaciers and ice sheets. The amount of sea level change at any given location depends on 7 global aspects of the climate system as well as on regional and local phenomena. As a result, regional sea 8 level change may differ from the global average. We consider sea level measured with respect to the surface 9 of the solid Earth which itself may be moving (relative sea level), and also sea level relative to the Earth’s 10 centre of mass (geocentric sea level). We also consider changes