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 | 25-09-2023

How is the sea?



Excerpts from the float originals podcast with Nikolaus Gelpke. He and his team have been publishing the magazine mare for 23 years. Hardly anyone else knows the culture, history and condition of the oceans as well as he does. In an interview with float originals, he gives a fantastic summary of how our ocean is doing.

Why do we treat the sea so badly?

“The sea doesn’t show itself that much. The sea always seems clean, friendly and in good condition. When you walk through the forest, you see: a tree has been felled or the tree is sick, has bark beetle problems or something like that. When it comes to the sea, you actually only see this when there is really serious littering – on the coast, for example. Otherwise you can't tell how the sea is doing. (...) The sea always puts on a good face when dealing with evil – and we are not used to that. Usually we see destroyed houses, polluted landscapes, dead trees. That's what we're aiming for and what we're trained for. And if we don’t see that, we automatically think: It’s fine.”


Which two factors within climate change have a major impact on the ocean?

“It’s acidification and warming. Acidification is very complex (…) which is why it is not often presented in the media, unlike plastic waste or oil pollution. You can show it very quickly, take photos, everyone understands it. Everyone knows that garbage and sticky birds don't belong in the sea. This is all easy to understand.
But when I start talking about PH values and carbon cycles, a lot of people stop listening. (…) To put it simply, the oceans absorb around 30 % of the CO2 that we produce – much more than the virgin forests or meadows absorb. 30 % is taken from the seas and deposited there. If you permanently introduce acidic material into a medium, it will eventually become acidic itself, i. e. the PH value of the sea changes and when you change a PH value you influence the creatures that live in the sea. We all know it from scrubbing the bathroom: we use vinegar to remove the limescale, i.e. Acid dissolves lime. If you look at it very simply, you can say that a reduction in the PH value causes lime to dissolve. Now a lot of life in the seas happens because of lime: coral reefs have lime skeletons, shells, many organisms that live on the bottom but also single-celled algae, e. g. Coccolithophorids. They are not as popular as whales and polar bears but they are much more important for the ecosystem. Coccolithophores are nanoplankton that can only be seen under a very good microscope, and they have a calcium carbonate shell. And if this calcareous shell dissolves or the reproduction rates of coccolithophores decrease, then the fundamentals of the food chain are changed. One of the most important foundations of the food chain begins with the coccolithophores, i. e. the very small phytoplankton species. These are plants that turn CO2 and light into biomass, the basis of life in the sea. And coccolithophores are ultimately responsible for the formation of clouds at sea. By changing the PH value, we actually change a lot because the lime of many organisms dissolves and that changes the ecosystem because the organisms that then die are followed by others that then go into this biological niche. The system is changing.

The second is warming, which is a bit easier to understand. A very well-known example is the Great Barrier Reef, the largest contiguous reef in the world, which is now – be careful – 50 % dead. (...) Coral bleaching due to increased temperatures. Corals have a symbiotic relationship with small zooxanthellae, which live as symbiotic partners in the corals and the coral animals are dependent on these zooxanthellae. These are also small algae that carry out photosynthesis. And they produce a poison that the coral perceives as negative and then repels the zooxanthellae and kills itself. This means the corals are really dying due to warming. Probably not salvageable. That is an influence.
Another influence is the melting of glaciers. (...) I often travel in the Arctic. You can also see how the glaciers are retreating in Greenland and Spitsbergen. If you then see how much the largest ice sheet in the world – namely the Greenland ice sheet – is melting, you can imagine, for example how the sea there becomes sweeter – that's fresh water that melts away. If now e.g. the Gulf Stream warms up even more and sweetens the Arctic at the same time – warm, sweet water is light, but the Gulf Stream drive is a pump of heavy, cold salt water, which flows down into the depths in the Arctic, north of the Barents Sea – the Engine gets stopped or weaker. The Gulf Stream may dry up or will probably weaken significantly – the modeling already shows that. But if the Gulf Stream stops flowing, you can imagine what it will look like here: As we not only have the palm trees in southern Ireland thanks to the Gulf Stream, but also warm winters compared to the same altitude over in Canada (...).
Another example: The ice cover in the Arctic is becoming so thin that more light comes through the ice in the spring and light comes earlier. Algae live on the underside of the pack ice that floats on the sea. And these algae are, among other things, the basic food for copepods, which are the very small crabs (krill), and they start to bloom earlier than before, i. e. spring flowering begins earlier. But the copepods have not yet adapted to this, i. e. the small larvae have not yet hatched. So the spring blossom is here and the small copepods are not there yet and cannot eat, i. e. the food chain is actually interrupted there too. There are fewer copepods, which is the basic diet for whales. It is already clear that many whales are starving because there is not enough food from the copepods.”

There are many small consequences in this biological organization that add up to a massive deterioration of the largest ecosystem in the world.


Why are the cods leaving the Baltic Sea?

“Because it’s already too hot for them. What people don't realize is that this delicate marine ecosystem has evolved over millions of years. And that even a very small change in temperature means that the organisms can no longer cope: if the cod now escapes from the Baltic Sea, for example, then that is because it is reacting to the small increase in temperature. And that's the same with the PH value. If you change all these factors a little bit, it has a big impact. The Baltic Sea is the sea with the fewest species in the world because it is the youngest. Because we have only had the Baltic Sea as a brackish water system since the last ice age. Before it was fresh water, then it was salt water – depending on how the Scandinavian plate rises and falls. But the brackish water system is the youngest marine ecological system in the world. And because it is so young, the organisms had less time to adapt to this brackish water system – for example, in Kiel 16 per mille salinity, compared to 32 per mille in the Atlantic or 36 per mille in the Mediterranean. (…) We already have pike in Finland – it’s already fresh water there. And the organisms had so little time to adapt to this system that there are so few species in the Baltic Sea. The sea with the fewest species in the world because 10,000 years weren't enough for it to develop. And we go and change these facts worldwide in no time and are surprised that it has consequences."

How do you look to the future?

“I always asked Elisabeth Mann Borgese: “When we talked about politics, what are you actually fighting for when you know how terrible the world is and that it is a fight against windmills?” Where do you get the strength from? And she said: If you keep saying that many times, I won't have the strength, but we have to keep going, even if we might feel like it doesn't make any sense, we have to keep fighting. (…) We have no choice but to commit ourselves now to making things better – even if we might think: “Oh, it might be too late. No, we have to move on. You have to move on radically. (…) And we have the options."