A controversial plan to save corals
bbc.com
bbc.com
Acidification is much worse, because you can't build calcium carbonate without carbonate ions, and acidification lowers the quantity of carbonate ions in the water. There is no natural selection for this, you can't build coral skeleton without the proper building blocks. It just makes all corals grow much more slowly, and thus when negative events happen it takes the reef much longer to recover. If the pH goes down low enough, at some point corals just can't build their structure anymore, which would be the end of the coral reefs as we know them.
And the only way to prevent ocean acidification is to lower the amount of co2 in the atmosphere, which isn't happening and wont happen for a very long time. It is going to be a tough century for the coral reefs.
Not-fun fact: The atmosphere is around 0.04% CO2, yet dissolved CO2 (either as CO2 or carbonic acid) is by far the largest dissolved gas in the ocean because of the reaction which forms carbonic acid. See the graph of atmospheric co2 vs ocean pH [1] to see how large the impact is.
1: http://ocean.si.edu/ocean-photos/ocean-acidification-graph
The best case scenarios are 1) global collapse of civilization or (and the one I am rooting for) 2) fusion power comes online and we use it to remove all of the excess carbon from the oceans and the atmosphere.
Aaaargh! This is not the only cause of coral bleaching! [Edit: removed apparently-distracting sentence.] Blaming climate change for coral death is sort of an "E: other" multiple-choice answer for when we've already eliminated sewage, agricultural pollution, chemical pollution, fishing techniques like cyanide, uncontrolled seaweed (often as a result of overfishing herbivorous fish), sedimentation, etc. Blaming climate change is the favorite maneuver of careless locals eager to blame the rest of the world for their dead reef.
There is coral bleaching on a massive scale that can't be explained by any of the reasons you mentioned.
Here in Fiji, last month we had ocean temperatures so high that thousands of fish died. This is unprecedented in Fiji: https://www.newswire.com.fj/community/fisheries/fish-kills-u...
The same happened in Vanuatu: http://eveningreport.nz/2016/02/09/vanuatu-heat-wave-suspect...
A week after that happened, the same warm seas spawned the second biggest tropical cyclone ever recorded in the entire Southern Hemisphere, killing ~50 people. https://en.wikipedia.org/wiki/Cyclone_Winston
The links I provided were indeed fish deaths because they illustrate how warm the seas have been recently. Coral bleaching occurs at lower temperatures than fish death.
Nature can do incredibly "smart" things, but it also has the benefit of operating on orders of 1,000 / 10,000 / 100,000 / 1,000,000s of years. I'd rather large portions of human population not be dead for most of that time until a new equilibrium is established.
Actually, the latest evidence is that evolution happens in relatively small time frames as conditions change. The problem is you're not guaranteed a handy mutation in that time frame - lots of species have gone extinct for lack of a trait that would have allowed them to survive.