The ‘other’ CO2 problem

163-6306_IMGMost of us are aware of the rising levels of anthropogenic carbon dioxide in the atmosphere and its impact on climate change but what about the potential loss of our oxygen supply? Far fewer of us are aware of what is sometimes referred to as the ‘other’ carbon dioxide problem, which is the acidification of the oceans. Carbon dioxide dissolves in the surface of the ocean when the concentration in the water is lower than in the atmosphere. Joanne Hopkins of the National Oceanography Centre in Liverpool describes this as the reverse of bubbles escaping when you open a fizzy drink, because the concentration of carbon dioxide in the air is less than in the drink. Carbon dioxide is also taken up in the ocean by tiny marine plants, known as phytoplankton, which convert it into organic matter and oxygen. Tiny marine animals, known as zooplankton, eat the phytoplankton and in turn are eaten and so on. Phytoplankton are important not just because they are the bottom of the food chain but also because they produce about half the oxygen that we breathe. The problem is that dissolved carbon dioxide is shifting the pH balance of the oceans which is beginning to cause demineralisation of microorganisms the ocean. At a recent Royal Society Regional Meeting in Bristol, Professor Daniela Schmidt described this as analogous to osteoporosis, a ‘brittle’ bone disease suffered by humans. Many years ago, my research group worked with a pathologist, Dr Dennis Cotton to examine whether it was possible that osteoporosis sufferers could break their leg and fall over rather than fall over and break their leg. In other words, could osteoporosis change the material properties of bone so dramatically that the structural integrity was insufficient for everyday activities such as getting out of bed or walking upstairs? Our answers at the time were inconclusive, at least in the generic case. Professor Schmidt is working with another team of engineers to examine the structural integrity of microorganisms in the oceans and the impact of demineralisation. The concern is that they could become structurally unstable and die and this could lead to a major reduction in our oxygen supply.

Ok, there is a lot of uncertainty about the series of interactions described above, about the magnitude of the effects and about the ability of ecosystems to adapt to the new conditions. However, the potential consequences are so catastrophic that we should not ignore them. Urgent action is needed to reduce our production of carbon dioxide, and since our governments appear incapable of action we have to take individual responsibilty as advocated by Kofi Annan and reported in my post entitled ‘New Year Resolution’ on December 31st, 2014.

By the way, look out for the announcement of the $2M Wendy Schmidt Ocean Health XPrize on July 20th to one of five teams of scientists for the best sensor for making real-time measurements of ocean acidity.


Bell R, The removal of a service we can’t do without’, The Observer, 25.01.15.

Schmidt D, Some don’t like it hot, Geology, 42(9):831-832, 2014.

Brodie et al, The future of the northeast Atlantic benthic flora in a high CO2 world, Ecology and Evolution, 4(13):2787-2798, 2014.

Cotton DWK, Whitehead CL, Vyas S, Cooper C & Patterson EA, Are hip fractures caused by falling and breaking or breaking and falling? Photoelastic stress analysis, Forensic Science Int. 65: 105-112, 1994.


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