A sprinkle of limestone could help oceans absorb CO2
14 May 2008, Kate Ravilious, Magazine issue 2656
GRIND it down, pour in a sprinkle here and a dash there, and wait for results.
That's the recipe for helping the oceans to absorb more of our carbon dioxide emissions: add limestone.
It may not only help reduce global warming but could even reinvigorate ailing coral reefs.
When atmospheric CO2 dissolves in the ocean, it reacts with carbonate ions in the surface waters to form bicarbonate ions.
While this helps keep the acidity of the ocean constant, it lowers the concentration of carbonate ions.
This makes the rise in atmospheric CO2 bad news for corals and other organisms which build their exoskeletons by absorbing carbonate ions along with calcium.
Ultimately the oceans could also become less able to absorb atmospheric CO2, as there are fewer carbonate ions around to mop up the CO2.