Réchauffement climatique : les océans menacés, oubliés de la COP21

Sujets

• Union internationale pour la conservation de la nature
• Océan
• Réchauffement climatique
• COP

Informations

• Publié par: Fil_actu
• Publié le: 07 septembre 2016
• Nombre de lectures: 5
• Langue: English
• Poids de l'ouvrage: 19 Mo

Extrait

Explaining Ocean Warming: Causes, scale, effects and consequences Edited by D. Laffoley and J. M. Baxter

September 2016

IUCN GLOBAL MARINE AND POLAR PROGRAMME

Explaining Ocean Warming: Causes, scale, effects and consequences

Explaining Ocean Warming: Causes, scale, effects and consequences Edited by D. Laffoley and J. M. Baxter

September 2016

The designation of geographical entities in this book, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of IUCN concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries.

The views expressed in this publication do not necessarily reect those of IUCN.

Published by:

Copyright:

Citation:

ISBN:

DOI:

Cover photos:

Layout by:

Available from:

IUCN, Gland, Switzerland

© 2016 International Union for Conservation of Nature and Natural Resources Reproduction of this publication for educational or other non-commercial purposes is authorized without prior written permission from the copyright holder provided the source is fully acknowledged. Reproduction of this publication for resale or other commercial purposes is prohibited without prior written permission of the copyright holder.

Laffoley, D. & Baxter, J. M. (editors). 2016.Explaining ocean warming: Causes, scale, effects and consequences. Full report. Gland, Switzerland: IUCN. 456 pp. Individual chapters within this report should be referenced as: Author(s). 2016. Title of chapter.Laffoley, D., & Baxter, J.M. (editors). 2016. Explaining ocean warming: In: Causes, scale, effects and consequences. Full report. Gland, Switzerland: IUCN. pp. xxx.

978-2-8317-1806-4

http://dx.doi.org/10.2305/IUCN.CH.2016.08.en

Clockwise from top: King penguins (Aptenodytes patagonicus) on Middle Beach (Brothers Point in distance), Macquarie Island, Southern Ocean. (© Robbie Kilpatrick/Australian Antarctic Division, November 2015, Image RS31770,Image Antarctica); a colony of black coral with small crabs moving amongst the branches (image courtesy of Department of BIS, UK); seagrass (Zostera marina)©James; Hurricane Catarina on SNH/Ben March 26th, 2004, off SE Brazil. Image courtesy of NASA.

Unit Graphics, Serbia

IUCN (International Union for Conservation of Nature) Global Marine and Polar Programme (GMPP) Rue Mauverney 28 1196 Gland Switzerland Tel [phone] Fax [phone] [e-mail] www.iucn.org/resources/publications

With grateful thanks to XL Catlin and the Total Foundation for their generous înancial support.

Index

Foreword                                                                                7 Preface                                                                                  8 Executive Summary                                                                       10 Acknowledgements                                                                       12

1 Ocean warming: setting the scene                                                        17 2 Cascading effects - from species to ecosystems to services                                   47 3. The signiIcance of warming seas for species and ecosystems                             55   3.1 Impacts and effects of ocean warming on micro-organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57  3.2 Impacts and effects of ocean warming on plankton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75  3.3 Impacts and effects of ocean warming on seaweeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87  3.4 Impacts and effects of ocean warming on tidal marsh and tidal freshwater forest ecosystems . . . . . . . 105  3.5 Impacts and effects of ocean warming on seagrass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121  3.6 Impacts and effects of ocean warming on mangrove species and ecosystems . . . . . . . . . . . . . . . . . . 135  3.7 Impacts and effects of ocean warming on intertidal rocky habitats . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147  3.8 Impacts and effects of ocean warming on coral reefs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177  3.9 Impacts and effects of ocean warming on deep sea communities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 3.10 Impacts and effects of ocean warming on jellyîsh213. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11 Impacts and effects of ocean warming on marine îshes239. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.12 Imapcts and effects of ocean warming on pelagic tunas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 3.13 Impacts and effects of ocean warming on seabirds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 3.14 Impacts and effects of ocean warming on marine turtles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 3.15 Impacts and effects of ocean warming on marine mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 3.16 Impacts and effects of ocean warming on Arctic ecosystems and species. . . . . . . . . . . . . . . . . . . . . . 321 3.17 Impacts and effects of ocean warming on Antarctic ecosystems and species . . . . . . . . . . . . . . . . . . . 337 4. The signiIcance of warming seas for ocean ‘goods and services’                           357  4.1 Impacts and effects of ocean warming on the weather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359  4.2 Impacts and effects of ocean warming on carbon management including methane hydrates . . . . . . . 373  4.3 Impacts and effects of ocean warming on the protection of coasts by habitat-forming species . . . . . . 389  4.4 Impacts and effects of ocean warming on marine phytoplankton and harmful algal blooms . . . . . . . . . 399  4.5 Impacts and effects of ocean warming on the contributions of îsheries and aquaculture  t. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409o food security  4.6 Impacts and effects of ocean warming on human health (disease) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439 5 Conclusions and recommendations                                                      451

Ocean Warming

5

6

Ocean Warming

Foreword

Our triumphant march through the advancement of the sciences, medicine, technology and sociology has provided humans with an unprecedented level of human betterment and well-being. We live longer and at various levels of comfort and entertainment, and have spread this mode of living - albeit unequally -across the earth. And yet, after several thousand years we have arrived at a critical turning point in our development.

Scientiîc analyses of the global climate system have provided us with the ability to understand the challenges created by rising greenhouse gas levels in the atmosphere, but despite the remarkable level of understanding achieved to date, there is much more work to be done. In particular, while the oceans cover 71% of the Earth’s surface, apart from the impact of rising sea levels on coastal areas caused by ocean warming and expansion and the melting of land-based glaciers, insufîcient attention has been given to the range of problems associated with the warming of the oceans. The present report addresses that gap in our knowledge. It is the most comprehensive review available of the science and implications of ocean warming.

This report is well-timed, coming in the aftermath of the ground-breaking agreement achieved at COP21 in Paris on ° 12.12.15. The nations of the world decided to limit global warming to less than 2 C above the pre-industrial average temperature. It is hoped that the challenges to the beneîts we receive from the ocean ecosystems as set out here will lead to a renewed interest amongst the political and social communities in the state of our oceans. To manage the risks will require both urgent actions and a quest for deeper scientiîc understanding. We will need this to protect the Earth’s ecosystems through sustainable living.

Sir David King UK Foreign Secretary’s Special Representative on Climate Change

OceanWarmiing

7

Preface

Ocean warming may well turn out to be the greatest hidden challenge of our generation. Whilst some may be aware of the challenges a warming ocean presents to coral reefs, few know about the other consequences this holds for the ocean. Ocean acidiîcation emerged as a new story around 2004, with problems already being encountered due to changes in ocean chemistry, and yet add ocean warming and there is a far bigger story to tell. In this report, we assess the scale of the challenge and explore this issue from a range of different perspectives – oceanography, ecosystems and species. We also look at the impacts ocean warming might have on the every-day beneîts we derive from the ocean – its ‘goods and services’.

This is a very timely report. We know the ocean is warming. Until very recently, the debate on climate change has focused on speciîc themes such as land surface temperatures, melting ice caps in Greenland and Polar Regions, and shrinking glaciers in mountain ranges. It has only occasionally mentioned the ocean. When the ocean was included, the issues discussed generally related to dramatic changes to coral reefs, as we have seen in 2016 when water temperature rises turning beautifully-coloured reefs a ghostly white from bleaching.

The arguments of sceptics have focused on an apparent pause in warming and yet as this report is being produced we are faced with the 14th consecutive month of record-breaking global temperatures on land. In the ocean, 2015 was recently analysed to have been the warmest year within the 136-year records of extended reconstructed sea surface temperature and the fourth such record-breaking year since 2005. The scale of ocean warming is truly staggering with the numbers so large that it is difîcult for most people to comprehend. A useful analysis undertaken 1 by the Grantham Institute in 2015 concluded that if the same amount of heat that has gone into the top 2000m of the ocean between 1955-2010 had gone into the lower 10km of the atmosphere, then the Earth would have seen a warming of 36°C. By factoring in the ocean, as this report shows, the perspective is fundamentally altered. What is perhaps more surprising, is that it is only in recent years that science on these cumulative ocean warming impacts has emerged and the story started to be revealed and heard.

The story that unfolds in the following pages should matter to everyone. Whether ocean warming impacts a particular group of organisms, alters the structures of ecosystems such as coral reefs, changes the very essence of environmental conditions, or indeed inuences weather, it impacts on everyone to some degree as we are an ocean planet. It has profound implications not just for ecosystems but also for the signiîcant number of coastal communities and valuable economies that depend on a healthy ocean. Up to now, the ocean has shielded us from the worst impacts of climate change. The costs is that its chemistry has been altered as it absorbed signiîcant amounts of the extra carbon dioxide we put into the atmosphere, but it has also warmed at an alarming rate in recent decades.

1 Whitmarsh F, Zika J, Cazaja A. 2015. Ocean heat uptake and the global surface temperature record, Grantham Institute, Brieîng paper No 14.

8

Ocean Warming

This report represents the most comprehensive review to date on ocean warming. To build up the report, leading scientists from around the world were invited to join with colleagues to contribute individual chapters. Each has been subject to peer review and tells in the scientist’s own words the scale and nature of changes being driven by ocean warming, often in association with other stressors, such as ocean acidiîcation and deoxygenation. It contains many recommendations from the scientists on capability gaps and research issues that need to be resolved if we are to tackle the impacts of ocean warming with greater conîdence in the future. The focus of the report is on gathering facts and knowledge and communicating this to show what is now happening in and to the ocean. There is purposefully much less focus on political ramiîcations. We hope that this report will help stimulate further debate and action on such issues.

We hope that the timing of this report after COP21 in Paris in late 2015 will keep up awareness that, despite greater recognition now being given to the ocean in climate discussions, the scale, intensity and nature of changes continue to grow. This report builds on the IPCC’s 2013 assessment, promotes their messages, and adds in new information published since then – over 25% of the peer reviewed papers quoted here have been published since 2014 - as well as highlighting lesser-known consequences of ocean warming on species, ecosystems and services for greater awareness and scrutiny in the future. Since the process was started to compile this report, IPCC has agreed to prepare a special report on climate change and oceans and the cryosphere. The papers in this report will, we hope, help that process and shape further thinking on the scale and consequences of climate change in our seas. Alongside this report, a second volume is in production, which will use the knowledge on ocean warming to revaluate the risks to society from the growing changes we see in the ocean.

Above all though, this report is the story of ocean warming and its consequences for all of us. It outlines cautionary tales about changes that are now underway in the ocean, often hidden and unseen, but nevertheless of great consequence. A warming ocean is one where changes to ecosystems, chemistry and processes are generating risks to the beneîts we and many other species receive and depend on during our lives: changes that are not theory, but now a reality supported by hard facts. For this reason, the relationship we have with the ocean matters more than ever and we hope this report will be instrumental in inspiring greater and urgent action to care for it.

Carl Gustaf Lundin Director IUCN’s Global Marine and Polar Programme

OceanWarmiing

Dan Laffoley Marine Vice Chair IUCN’s World Commission on Protected Areas

9