Press release

Climate change: Earth warming already leads to significant changes in oceans

[24. March 2014] 

Bremerhaven, 24 March 2014. The current and projected climate change is altering living conditions in the oceans faster than during comparable events in the past 65 million years. This is the conclusion drawn by AWI biologist Prof. Dr. Hans-Otto Pörtner, who will take part in the coordination phase for the second part of the Fifth Assessment Report on climate change in Yokohama, Japan starting tomorrow. The expert from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), jointly headed the work on the chapter “Ocean Systems” together with his American colleague David Karl. It summarises the knowledge regarding the already observed and future consequences of climate change for life in the oceans.

“It’s the first time that the IPCC has devoted so much attention to the topic of oceans. Two entire chapters of the Fifth Assessment Report, Part 2, focus on climate-related changes in the oceans and their consequences. Chapter 6, which we coordinated, examines climate change and possible adaptation options from a global perspective, chapter 30 describes the changes in selected oceanic regions,” says Hans-Otto Pörtner.

He and an international team of authors sifted through the entire research literature on the subject for nearly three and a half years, adds Pörtner. They compared data records, methods and results to one another, reviewed and assessed the cogency of the scientific arguments and forecasts, defined risks and identified uncertainties and gaps in knowledge.

“As a consequence of climate change, three factors have an impact that is altering the living conditions for fish, mammals, algae and other ocean dwellers. The most powerful driving force is currently ocean warming. It is already leading to significant changes. We observe, for instance, that fish species like the Atlantic cod shift their habitat poleward. The second factor, ocean acidification, will increase in significance in the coming decades according to forecasts and have substantial impacts at the global level and in specific ecosystems. The third key development relates to increasing oxygen deficiency. We feel its impacts, for example, in coastal regions where the number of extremely oxygen-deficient zones has risen significantly,” says Hans-Otto Pörtner.

In the 5th IPCC Assessment Report, which will be published in Yokohama at 9 am local time on 31 March 2014, the scientists will specify facts and figures for these changes, make predictions and point out the risks and costs climate change will generate. Beforehand, however, the leading IPCC authors will meet for the coordination phase beginning tomorrow in order to go through their “summary for political decision-makers” line by line together with government representatives. “In the discussion our aim is to achieve a consensus between governments and the scientific community,” states Hans-Otto Pörtner.


Notes for Editors:

Contact persons and interview requests:

During the coordination week from 25 to 29 March 2014 Prof. Dr. Hans-Otto Pörtner will be available for interviews on the general scientific background. As of 30 March, he can also talk about the results of the negotiations and specific subject matter of the report in compliance with the IPCC embargo rules (31 March, 2 am German time; 9 am Japanese time). Please coordinate all interview requests with Sina Löschke in AWI’s Press Office (tel: +49 471 4831-2008; e-mail: The IPCC press conference on publication of the second part of the report takes place in Yokohama on 31 March at 9 am local time. You will find all information and accreditation requirements on the website: (right-hand column).


AWI background material: (Please note: We are still filling these pages with English translations)

You will find comprehensibly prepared background material on the consequences of climate change for the oceans in general as well as for the Arctic Ocean, Southern Ocean and the North Sea in particular in our AWI Fact Sheets at  On request we would be glad to provide you with footage. In this case, too, please refer to Sina Löschke (tel: +49 471 4831-2008; e-mail:


Interview with Helmholtz experts (in German language only)

Two of the leading coordinating authors of the 5th IPCC Assessment Report, Part 2, come from the Helmholtz Association, AWI biologist Hans-Otto Pörtner and agricultural ecologist Dr. Josef Settele from the Helmholtz Centre for Environmental Research (UFZ) in Leipzig. You will find a joint interview with the two scientists here:


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The Alfred Wegener Institute researches in the Arctic, the Antarctic and oceans in the central and high latitudes. It coordinates polar research in Germany and provides important infrastructure such as the research icebreaker Polarstern and stations in the Arctic and Antarctic for the international science community. The Alfred Wegener Institute is one of the 18 research centres belonging to the Helmholtz Association, which is Germany's largest scientific organisation.



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Das Institut

Das Alfred-Wegener-Institut forscht in den Polarregionen und Ozeanen der mittleren und hohen Breiten. Als eines von 19 Forschungszentren der Helmholtz-Gemeinschaft koordiniert es Deutschlands Polarforschung und stellt Schiffe wie den Forschungseisbrecher Polarstern und Stationen für die internationale Wissenschaft zur Verfügung.