Category Archives: Background

Where and when

Current exhibition:

There are no current exhibition dates. All exhibition photos are also presented on this website.

Previous dates:

1 August – 31 October 2019:
UNESCO Weltnaturerbe Wattenmeer Besucherzentrum Norderney

8 January – 28 April 2019
Osnabrück, Museum am Schölerberg

10 July – 29 August 2018:
Bremen, Haus der Wissenschaft

8 December 2017 – 4 February 2018:
Rostock, Schiffbau- & Schifffahrtsmuseum

11 July – 27 August 2017:
Hamburg, Greenpeace Deutschland

16 May – 8 July 2017:
Oldenburg, Schlaues Haus

23 March – 7 May 2017:
Munich, Deutsches Museum

7 January – 26 February 2017
Tönning, Nationalpark-Zentrum Multimar Wattforum

20 September – 16 November 2016
Kiel, GEOMAR Helmholtz Centre for Ocean Research Kiel

Two forms of calcium carbonate: calcite and aragonite

The shells and skeletons of many marine organisms are made from either calcite or aragonite – two mineral forms of calcium carbonate. Scientists are particularly interested in aragonite, which is produced by many tropical corals, cold-water corals, pteropods and some molluscs. It is more soluble than calcite.

Organisms grow shells and skeletons more easily when carbonate ions in water are abundant – it is supersaturated. Unprotected shells and skeletons dissolve when carbonate ions in water are scarce – it is undersaturated or corrosive.

The saturation state Omega (Ω) describes the level of calcium carbonate saturation in seawater. If the saturation state for aragonite is less than 1 (Ω<1), conditions are corrosive (undersaturated) for aragonite-based shells and skeletons. If the saturation state is above 1 (Ω>1), waters are supersaturated with respect to calcium carbonate and conditions are favourable for shell formation. Coral growth benefits from a saturation state of 3 (Ω≥3).

Computer model projections show that the saturation state will be less than 3 in surface waters around tropical reefs by 2100 if CO2 emissions continue on the current trajectory.

Marine snow

Just like a steady snowfall, tiny organic particles – dead plankton and smaller organisms as well as their fecal products, but also sand, dust and soot – sink from the water surface to the sea floor. Much of this material that sticks together like snowflakes, is already consumed on its way down by microbes, zooplankton and filter feeders. In regions that are not reached by sunlight, marine snow is an important source of food.

Global climate change may disrupt this cycle: If stratification of the seawater increases due to rising temperatures, the marine snow could accumulate in one layer instead of sinking all the way down to poorly-lit depths. And since increasing acidification impairs calcification and less or lighter calcium carbonate are produced, this might also affect the sinking process. For this reason, some groups of organisms might find fewer nutrients than available under current conditions.

The Paleocene-Eocene Thermal Maximum (PETM)

Seen from a geological perspective, phases of ocean acidification are not new. During the Paleocene-Eocene Temperature Maximum (PETM) 55 million years ago, global temperatures rose by about 6 degrees Celsius in less than 10,000 years. The carbon dioxide concentrations in the atmosphere increased as well as the ocean’s acidity. Many calcifying benthic organisms died – but some species living at the surface survived.

The crucial difference: The changes that we are experiencing today are taking place at least ten times faster than during the PETM. Even species that reproduce fast and are thus able to adapt to changing conditions through evolution seem to find it harder to keep pace with the current rate of changes.

The IPCC’s Representative Concentration Pathways

For the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), new development scenarios were created. These “Representative Concentration Pathways” (RCPs) describe anticipated radiative forcings, i.e. the sum of the climate-related disturbances in the atmosphere, in watts per square meter. Model calculations translate the forcing into climatic changes evoked by them and reveal which greenhouse gas emissions they are based on.

Four of these RCPs are taken into account in the Fifth Progress Report: RCP2.6 (relatively low radiative forcing) RCP4.5 (mean radiative forcing) RCP6.0 (high radiative forcing) and RCP8.5 (very high radiative forcing).

The German Climate Computing Centre’s earth system model MPI-ESM helped to investigate how these scenarios affect global temperatures, sea ice melt, the sea level or acidification and carbonate saturation.

According to these calculations, the global mean temperature would increase by about 4.8 degrees Celsius compared to pre-industrial conditions by the year 2100 in the scenario RCP8.5. Only the scenario RCP2.6 would keep the average global temperature rise below the 2 degrees Celsius. To achieve this goal, global carbon dioxide emissions would have to remain at current levels until 2020 and decline to about 400 ppm (parts per million) by 2100. The particular sensitivity of tropical coral reefs requires such drastic measures: About fifty per cent of coral reefs can be obtained if the temperature rise would be limited to about 1.2 degrees Celsius.

Animation: Temperature changes in the RCP8.5 scenario:

Ocean acidification could be limited considerably with the medium scenario RCP4.5 and stabilize at a pH of slightly more than 7.9 – which still would be about 0.15 units more acidic than today. RCP2.6 suggests a decrease after 2050. However, the ocean reacts so slowly that 200 additional years would pass until today’s conditions would be restored.

Animation: Ocean acidification in the RCP8.5 scenario:

High-CO2 reefs: Where the future has already arrived

A brown-greenish lunar landscape covers the seafloor in some bays of Papua New Guinea. Poor in species, monotonous and separeted from the divers surroundings by curtains of rising bubbles. Is this what the future of tropical coral reefs looks like?

The volcanic carbon dioxide vents in the South Pacific archipelago provide scientists with a glimpse of the future. The gas causes the water to acidify. But only a few coral species such as the Porites genus are able to maintain their growth and reproduction at lower pH. And only algae and sea grasses can exist at locations of extreme acidities. Fish and other non-sessile creatures seem to avoid these areas.

In addition to ocean acidification, tropical coral reefs are also exposed to rising water temperatures. Therefore, the High-CO2-Reefs of Papua New Guinea make up an excellent natural laboratory for research on impacts of ocean acidification – but many other findings from other experiments and model calculation need to be considered in order to create a comprehensive projection.

In this video portrait, BIOACID scientist Dr. Christiane Hassenrück tells about her expedition to the high-CO2 reefs and her research on microorganisms – tiny bacteria that play a crucial role for these ecosystems.

Research submersible JAGO

Germany’s only manned research submersible is based at GEOMAR since January 2006. But its history goes back much further: In 1988, the oceanographer Hans Fricke, the submersible pilot and technician Jürgen Schauer, biologist Karen Hissmann and the allrounder Lutz Kasang started constructing the underwater vehicle at the former Max Planck Institute for Behavioral Physiology in the Bavarian village Seewiesen. Their goal was to watch the legendary coelacanth in its natural environment.

JAGO’S first dive was celebrated on 17 August 1989 at Lake Starnberg. Soon after, the fresh water swimmer became a saltwater being: On November 2, 1989 JAGO explored the steep lava slopes at the island Grande Comore for the first time. Initially, the legendary “dinofish” did not show up. But the fourth attempt to meet it was successful: Even three coelacanths dwelled in a cave that reached 195 metres into the rock.

Since the impressive experience in the Comoros, JAGO has gone places. It has been in the South Pacific and in Iceland, the Black and the Red Sea, in Bavaria’s lakes and in the Kiel Fjord. In 1997, marine biologists explored cold-water coral reefs off the Norwegian coast with JAGO for the first time. Since then, the fragile reefs have become a second home to the submersible.

Characteristics JAGO:
Length: 3 metres
Width: 2 metres
Height: 2.5 metres
Weight in air: 3000 kilogrammes
Depth: 400 metres
Speed: 1 knot
Crew: 1 pilot, 1 observer

In this video portrait, Janina Büscher, marine biologist at GEOMAR, tells about her JAGO dives to cold-water corals reefs off Norway and her laboratory experiments that help her to better understand how climate change affects these animals.

More about JAGO on the GEOMAR website:

EPOCA – European Project on Ocean Acidification

The European Project on Ocean Acidification (EPOCA) was the first international research effort on ocean acidification. It was launched in May 2008 with the overall goal to further our understanding of the biological, ecological, biogeochemical, and societal implications of ocean acidification. The project comprised more than 160 scientists from 32 institutions in Belgium, France, Germany, Iceland, Italy, The Netherlands, Norway, Sweden, Switzerland, United Kingdom). EPOCA was co-funded by the European Commission for four years as part of the Seventh Framework Programme.

The 2010 mesocosm experiment in Svalbard was conduced under the umbrella of EPOCA in cooperation with BIOACID.

EPOCA website:

Blog about the 2010 mesocosm experiment in Svalbard / EPOCA Arctic Campaign 2010:

BIOACID – Biological Impacts of Ocean Acidification

Exploring Ocean Change

As one of the largest national research programmes on ocean acidification, BIOACID has contributed to quantifying the effects of ocean acidification on marine organisms and their habitats, unravelling the mechanisms underlying the observed responses, assessing the potential for evolutionary adaptation, and determining how these responses are modulated by other environmental drivers.
In its third phase that started on October 1, 2015, BIOACID aimed to synthesize the information gained on ocean acidification impacts in an integrated assessment of sensitivities and uncertainties in order to identify the potential thresholds associated with ocean acidification, evaluated possible socio-economic consequences, identified management options and communicated its knowledge towards a wide audience, ranging from the scientific community, stakeholders and decision makers to the general public.

The Federal Ministry of Education and Research (BMBF) supported the project that was coordinated by GEOMAR Helmholtz Centre for Ocean Research Kiel.

READ MORE: A changing ocean


The KOSMOS mesocosms

In the field, the KOSMOS mesocosms look like tiny floating pavilions. Just the upper one and a half metres of the floatation frames stick out of the water, shining in bright orange between the waves, and their transparent umbrella hood sparkles in the sun.

When the photographer Nick Cobbing visited the mesocosm experiment in Spitsbergen in 2010, he said: If you would develop research equipment that looks good and helps to convey the subject of ocean acidification – they looked pretty much the same as the KOSMOS mesocosms.

But of course, a research question prompted the development of the mesocosms: After laboratory studies had revealed first findings on the effects of ocean acidification on individual species, researchers wanted to assess to what extent they could be translated to communities in their natural environment. It became necessary to isolate part of the marine ecosystem, keep as many conditions in today’s state, but elevate the acidification to values predicted for the future. A giant test tube was needed!

In the early 2000s the KOSMOS system was developed in Kiel. The abbreviation stands for Kiel off-shore Mesocosms for Future Ocean Simulations.

The nine experimental units consist of six seven and a half metres high floatation tubes, between which a cylindrical bag with a diameter of two and a length of up to 25 meters hangs. A research vessel takes the KOSMOS system to its respective operation site. When the equipment is deployed, the bags are still folded like an accordion. As soon as they are lowered, each bag encloses a water column and all planktonic organisms living in it. At the bottom, a kind of large funnel is attached: the sediment trap, which collects all material that sinks down inside the mesocosm.

The “spider” makes the future happen inside the mesocosms: Seawater saturated with carbon dioxide is pumped through the spiny, one and a half metres wide instrument’s 80 thin plastic tubes into the mesocosms until they reach the desired concentration. And then, the sample routine can begin…

In this video portrait, Prof. Ulf Riebesell, marine biologist at GEOMAR and BIOACID coordinator, tells how the KOSMOS mesocosms were developed and why he enjoys the mesocosm experiments.

The pH

The pH indicates how acidic or basic (alkaline) a liquid is. It depends on the concentration of hydrogen ions in an aqueous solution. If the number of hydrogen ions decreases, the pH increases. If the number of hydrogen ions increases, the pH decreases.

Pure water has a pH of 7. Lower values are described as acidic, and higher ones as basic. Since the pH is based on a logarithmic scale, a change from pH 8 to pH 7 corresponds to a tenfold increase in acidity. If the pH of a liquid changes from 7 to 6, there are ten times as many additional hydrogen ions as in a change from pH 8 to pH 7.

Since the beginning of the Industrial Revolution, the average pH of the global ocean surface has already fallen from 8.2 to 8.1, corresponding to an increase in acidity of about 26 per cent. Values of 7.8 to 7.9 are expected by 2100, representing a doubling of acidity compared to the time before the industrial revolution.

It is unlikely that the open-ocean surface layer will ever become truly acidic (drop below pH 7.0), because seawater is buffered by dissolved salts. That’s why scientists emphasize it “acidifies” or becomes “more acidic”, but not “acidic”. The term “ocean acidification” refers to a pH shift towards the acidic end of the pH scale – similar to the way we would describe an increase in air temperature from -20 degrees Celsius to 0 degrees Celsius: The air is still cold, but we say “it is “warming.”