"Rich" oceans exacerbate climate change

Climate change ensures that the southern ocean draws less carbon dioxide from the atmosphere than one would expect

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The oceans absorb almost a third of the carbon dioxide that blasts humanity into the atmosphere - and the more greenhouse gas pollutes the air, the more it should dissipate in the oceans. It does not do it. At least in the southern ocean, a saturation effect has become noticeable in the last 25 years, as Max Planck researchers report in the journal "Science". After all, climate change - which greenhouse gases at least contribute to - is disrupting the carbon cycle of the oceans.


When a forest or an ocean absorbs more carbon dioxide than it gives off, geochemists speak of a carbon sink. And at least into the oceans, the atmosphere should be the more carbon dioxide the more it contains. This is a matter of chemical equilibrium and can be observed in principle in a Wassersprudler. If the oceans adhered to this principle, they could mitigate climate change. "But climate change ensures that the oceans absorb less carbon dioxide, " explains Martin Heimann, Director at the Max Planck Institute for Biogeochemistry in Jena. "This leaves more carbon dioxide emitted by humans in the atmosphere, which in turn increases climate change."

Checked feedback

This positive feedback has now been measured for the first time by an international team of scientists led by the Max Planck Institute for Biogeochemistry in Jena. Theoretically, scientists have been predicting this effect for some time. Now, researchers from, among others, the University of East Anglia and the British Antarctic Survey have evaluated measurements from 42 stations distributed throughout the Earth.

Some of the measuring stations have registered the concentration of the greenhouse gas in their environment since the beginning of the 1980s. How much the concentrations between the individual stations increase or decrease depends, among other things, on the air flows. But also how much gas the sinks pull out of the air. Conversely, the researchers were able to calculate from their measurements so how much carbon dioxide absorbs the sink of the southern ocean. And how its capacity has changed over the past 25 years. display

Climate change is changing wind systems

Actually, the southern ocean should absorb more greenhouse gas today than at the beginning of the measurements. Finally, the carbon dioxide concentration in the atmosphere has increased significantly. Instead, the picture has stagnated in the last 25 years, as the measurements of the team of scientists prove. The fault is climate change, which is fueling the winds over the southern ocean. These in turn change the ocean currents. Thus, more water reaches the surface, which is already saturated with carbon. Similar phenomena are to be expected elsewhere: "We have to assume that such feedback will increase climate change in other parts of the world, " says Heimann.

(Max Planck Institute for Biogeochemistry, 21.05.2007 - AHE)