Burning fossil fuels does not affect only the air. Scientists have been long aware of the fact that the greenhouse gases reach the atmosphere only in a 60% proportion. The rest of it ends up contaminating the oceans. However, there are some conditions that create this kind of exposure. If the waters are cold, they are going to absorb more carbon dioxide than usual and vice-versa. So, as the temperatures of the oceans are getting warmer, the fossil fuels are no longer entering the waters, and they are redirected into the atmosphere where they can accelerate global warming. However, a recent paper found that the ocean oxygen dropped by 2% during the last 50 years.
A recent study was published in the journal Nature. The team of scientists wanted to find out how oceans have absorbed carbon dioxide over time. The waters might get hotter, but they weren’t always like this. Even so, a mysterious phenomenon has caught the attention of the scientists. Even though the temperatures go up, the oceans have increased their capacity of absorption.
The scientists focused on a particular ocean current of major importance. This is about the overturning circulation. Under its influence, the dense, salty waters that float on the surface are sinking to the bottom while their place is taken by colder waters with a smaller amount of salt from bellow. However, the scientists found that this phenomenon is slowing down and they believe the reason is the global warming.
One possible explanation is that the global warming leads to the ice melt in the Arctic. The composition of the new water is similar to that from the bottom of the oceans, which is less salty. Because it comes in large amounts, the freshwater can halt the overturning circulation. On the other hand, its slowdown can be seen as a natural phenomenon.
For their study, the researchers analyzed the patterns of the ocean currents with chemicals that can trace the course of waters. With a slower overturning circulation, the carbon-rich waters from bellow are not making it to the surface. Thus, the carbon dioxide cannot be released into the atmosphere, and it remains under water. This led to ocean oxygen getting thinner by 2% since 1960.
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