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Oceans : Ocean Acidification  


Joined: 2 years ago
Posts: 22
20/08/2018 5:52 pm  

Over the last few decades, it has been demonstrated that ocean carbon dioxide levels have risen because of increased carbon dioxide in the atmosphere. The ocean absorbs CO2 as the concentrations rise in the atmosphere. So what does this mean?

Oceans become more acidic which in turn upsets the ph balance of the organisms that thrive on this marine ecosystem. Humans depend on the ocean for food and survival. To read more on this--

The GCAS Ocean Climate agenda:

The UNEP site on the impacts of ocean acidification on marine biodiversity.




Bronze Registered
Joined: 2 years ago
Posts: 4
14/09/2018 8:00 pm  

It is a very interesting subject.  I am curious how the melting ice caps influence this e.g. they may mask the acidic increase for a period.  I don't have an understanding for the rates of change for each so any input (apologies if I missed it in the links) would be appreciated.

Joined: 2 years ago
Posts: 8
14/09/2018 11:30 pm  

Hey klande, great question! I remember learning about this in school, but I couldn’t for the life of me remember. I ended up looking it up :p turns out that, fresh water from melting ice caps dilutes the concentrations of all the various components of the carbonate system in seawater, as well as the total alkalinity and salinity (both of which affect pH).

For example, a liter of “typical” Arctic seawater (temperature, 5°C; salinity, 35; total alkalinity, 2244 micromoles/kilogram) that is exposed to today’s atmospheric CO2 level of 390 ppm has a total carbon content of 2100 micromoles/kilogram and a pH of 8.04 (total scale, here and below).  Adding a kilogram of freshwater to the kilogram of seawater would dilute the salinity, alkalinity, and carbon content to half of what they were, and the initial pH would increase to 8.21.  However, that seawater is out of equilibrium with the atmosphere (it now has a pCO2 of 151 ppm, while the pCO2 level of the overlying atmosphere is 390 ppm) and so it will absorb CO2 until the seawater pCO2 also equals 390 ppm, at which point the pH will have dropped to 7.83.

I hope this helps better your understanding! 🙂

 Richard A. Feely, Senior Scientist, NOAA Pacific Marine Environmental Laboratory, USA; Joan Kleypas, Scientist III, National Center for Atmospheric Research, USA