Edited by D. Laffoley and J. M. Baxter
Ocean warming may well turn out to be the greatest hidden challenge of our generation. Whilst some may be awareof the challenges a warming ocean presents to coral reefs, few know about the other consequences this holds for the ocean. Ocean acidification 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 benefits 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 specific 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 difficult for most people to comprehend. A useful analysis undertaken by the Grantham Institute(1) 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 influences 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 significant 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 significant amounts of the extra carbon dioxide we put into the atmosphere, but it has also warmed at an alarming rate in recent decades.
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 acidification 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 confidence 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 ramifications. 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 benefits 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
IUCN’s Global Marine and Polar Programme
Marine Vice Chair
IUCN’s World Commission on Protected Areas
1 Whitmarsh F, Zika J, Cazaja A. 2015. Ocean heat uptake and the global surface temperature record, Grantham Institute, Briefing paper No 14
See the report: