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Jana Willim: „Seagrass meadows are the coral reefs of the Baltic Sea“.

Seagrass meadows are true all-rounders: They create a three-dimensional habitat for many marine organisms, offering both shelter and food. They improve water quality and store carbon dioxide (CO₂) long-term in the sediment, in their roots and rhizomes. Additionally, they protect coastlines by slowing down waves and stabilizing sandy seabeds with their roots.

Like coral reefs, seagrass meadows are vital ecosystems and habitats in the ocean and are therefore essential for marine biodiversity. However, they are also sensitive to external influences such as excess nutrients, increasing human use of coastal areas, and ongoing warming. The result: in many regions, seagrass populations are declining. This makes it all the more important to protect and restore these meadows. NGOs and citizens are contributing by replanting seagrass in coastal areas of the Baltic Sea.

At ºÚÁÏÊÓƵ Helmholtz Centre for Ocean Research Kiel, scientists are studying how seagrass can be restored, how climate-resilient seagrass can be cultivated, and how much CO₂ is stored in Baltic Sea seagrass meadows.

Jana Willim is a doctoral researcher in the Marine Evolutionary Ecology research unit at ºÚÁÏÊÓƵ Helmholtz Centre for Ocean Research. Her research focuses particularly on restoration measures and the adaptation processes of seagrass to environmental stressors.

Florian Schütte: „The ocean absorbs over 90 per cent of the excess heat“.

Since the beginning of industrialisation, mankind has had a massive impact on the Earth's natural heat balance by burning fossil fuels. Since then, the ocean has absorbed more than 90 per cent of the additional heat released. This means that the oceans act as a buffer, without which the earth would already be much warmer today.

However, this extreme warming of the oceans also has many negative consequences: The higher temperatures of the water surface, can lead to increased evaporation - and thus regionally to more precipitation. In tropical regions, the warmer sea surface also favours the development and intensification of tropical cyclones.

In addition, the warming and increased stratification of the upper water layers reduces the mixing of the water. This has an impact on the supply of oxygen and nutrients to living organisms - and therefore on the marine ecosystem. Last but not least, ocean warming contributes to the melting of ice, particularly in the Antarctic and Greenland. This in turn accelerates sea level rise. By the end of the century, an average rise of 50 to 100 centimetres can be expected. Even if we were to stop emitting greenhouse gases now, sea levels would continue to rise for several centuries, as the climate system reacts slowly to such changes.

Florian Schütte is Junior Professor of Physical Oceanography at the ºÚÁÏÊÓƵ Helmholtz Centre for Ocean Research Kiel. His research interests include the physical observation of oceanic eddies, which can be found throughout the world's oceans.

Morelia Urlaub: "We monitor volcanic slopes under water".

Just like on land, underwater slopes can also begin to slide. However, the scale of submarine landslides often far exceeds those on land. Around one quarter of all tsunamis are triggered by underwater landslides. The causes of such submarine slope failures are still poorly understood, and the dynamic processes on the seafloor remain insufficiently explored. This is mainly because the traces of landslides lie hidden under several hundred or even thousands of meters of water – and the layer that initially gives way is usually destroyed in the process.

Comprehensive mapping of the seafloor using autonomous underwater vehicles (AUVs) and targeted long-term monitoring aim to close these knowledge gaps. For example, acoustic seafloor positioning networks are being deployed. These consist of several autonomous transponders that communicate with each other. By measuring the travel time of acoustic signals, the distance between the devices can be determined with centimeter accuracy. If the signal travel time changes (for example, due to a slope failure), the relative movements between devices can be calculated.

The goal of this research is to develop an early warning system on the seafloor to collect real-time data on earthquakes, ground movements, and volcanic activity. This would enable reliable monitoring of submarine volcanoes.

Morelia Urlaub is a junior professor of Marine Geomechanics at ºÚÁÏÊÓƵ Helmholtz Centre for Ocean Research and Kiel University. Her research focuses on submarine natural hazards, particularly those caused by slope instabilities and underwater landslides. She investigates these processes through long-term seafloor observations and numerical modeling.

Amavi Silva: „The ocean is our planet's biggest carbon storage“.

The ocean is our ally in the fight against climate change. Since the beginning of industrialization, the ocean has absorbed around a quarter of the carbon dioxide (CO₂) released by human activities. This natural buffering effect has significantly slowed global warming. But CO₂ uptake comes at a high cost: the ocean water is becoming more acidic.

CO₂ enters the ocean at the surface, where it dissolves from the air into the seawater. Whether and how much CO₂ is absorbed depends primarily on the difference in what’s called the CO₂ partial pressure between the atmosphere and the surface ocean. Put simply, this is the pressure generated by the CO2 dissolved in the surface water and the CO2 in the atmosphere. The natural gas exchange between ocean and atmosphere always works to balance out this pressure difference.

At ºÚÁÏÊÓƵ, researchers are exploring ways to increase the ocean’s ability to absorb CO₂ in the future – in order to help meet international climate goals and offset unavoidable emissions. The top priority on the path to climate neutrality is and remains the avoidance of emissions.

Amavi Silva is a marine biogeochemist (postdoc) at ºÚÁÏÊÓƵ Helmholtz Centre for Ocean Research Kiel. Her research aims to understand the dynamics of the sea surface microlayer – the ocean’s ‘skin’ that controls the air-sea exchange of CO₂.