Global Warming and Its Effect on The Ocean

Prior to this post, I thought that oxygen was just generally found in the Ocean and didn't need any type of support and until this post, I didn't know there were seas that act as the Ocean's lung and they allow oxygen to flow into the deep oceans. One of such Ocean lung is the Labrador Sea which is found between Canada and Greenland, and it is responsible for about half of the oxygen in the deep sea of the Atlantic from the Equator.

This sea allows for oxygen to get to the Atlantic ocean using what is referred to as Density-Driven Circulation and this just simply has to do with the movement of seawater based on density. While the Ocean is made of sea water generally, not all sea water are equal as they differ in density from one another and these causes sea water to have layers depending on their density where the less dense water is at the top while the more dense water stays below.

^Wikimedia

Density of sea water is dependent on two things which are temperature and salinity with the warmer water being less dense compared to the cooler water, and the less salty water is less dense compared to the saltier sea water which is more dense. Following that explanation, we can put together that the colder and saltier water is more dense compared to the warmer and less salty water which is less dense.

To put this into perspective, the Golf Stream which carries water to the Labrador Sea is very salty but because it is warm, it stays just at the surface. At the surface, the water is in contact with the atmosphere and it is able to absorb oxygen. When the warm water reaches the Labrador sea, it begins to cool and begins to sink since it is very dense and this water moves to the bottom of the ocean.

^Flickr

The oxygen that was absorbed is then taken to the deep ocean but as it moves, it reaches a mixing zone where it is moved south towards the equator. This mixing zone is about 2km down and at this point, deep sea organisms use the oxygen. We can see that the Labrador and the process is important for life in the ocean but it looks like climate change is about to cause some detrimental issues.

With climate change, ice have been melting, and the Greenland Ice sheet is not spared. No matter how salty a sea water is, once it freezes, only the fresh water becomes ice while the salt in the sea water stays dissolved in the sea water that remains making the water saltier. With the melting of the Greenland Ice Sheet the ice of fresh water is falling into the sea water thereby reducing the concentration of sea water. Since salt is a component of density in ocean water, it is needed to sink and if it is diluted, the salt content reduces and inking might become a problem as it brings less oxygen to the deep sea since less of the sea water sink.

The changes already began but the extend of the changes is still yet to be known but we can ascertain that if we continue with an rise in global warming, then it might have greater negative consequence on marine life. If we are able to make changes and reduce global warming a lot of things would get restored and heal including the ocean.

^Reference

^{https://cosmosmagazine.com/earth/oceans/lungs-ocean-deep-sea-life/
https://rwu.pressbooks.pub/webboceanography/chapter/9-8-thermohaline-circulation/
https://agupubs.onlinelibrary.wiley.com/doi/pdfdirect/10.1029/2006GL026815
https://eos.org/articles/oxygen-levels-measured-in-a-lung-of-the-deep-ocean
https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2007GC001604
https://royalsocietypublishing.org/doi/full/10.1098/rsta.2016.0321
https://bg.copernicus.org/articles/19/437/2022/
https://www.sciencedaily.com/releases/2017/10/171013113012.htm}