For the scientists. How is Climate change exactly bleachin the corals?
I know that climate change is dumping 30 million tons of co2 in the oceans everyday, but how is that increasing the acidity of ocean water, bleaching the corals? I though you needed hydrogen ions to increase the acidity and co2 molecules have no H ions.
dissolved in water CO2 undergoes a reaction
CO2 + H2O –> H2CO3 –> H+ + HCO3-
forming carbonic acid as well as bicarbonate
Carbon dioxide dissolved in water forms carbonic acid, H2CO3. The hydrogen atoms in carbonic acid are somewhat weakly bound, and can disassociate themselves to become free hydrogen radicals, H+. When this happens, there is no hydroxyl radical (OH-) to pair with, hence the overall level of H+ rises and the acidity rises.
It’s not acidity, it’s the temperature. I remembered that from Nature on PBS. Here it is from Wikipedia:
Coral bleaching refers to the loss of color of corals due to stress-induced expulsion of symbiotic unicellular algae. The corals that form the structure of the great reef ecosystems of tropical seas depend on a symbiotic relationship with photosynthesizing unicellular algae called zooxanthellae that live within their tissues. Zooxanthellae give coral its particular coloration, depending on the clade living within the coral. Under stress, corals may expel their zooxantheallae, which leads to a lighter or completely white appearance, hence the term "bleached".
when that 30 million pounds of CO2 goes into the ocean, it chemically reacts with H2O, forming carbonic acid, H2CO3. The hydrogen in H2CO3 can break off resulting in HCO3- and H+. that H+ increases the acidity