The Coral Reef
Climate change causes "coral bleaching". Coral reefs are very cognizant to changing temperatures. If the temperature in the water is too high for a long period of time, zooxanthellae ( the stuff they depend on for food ) starts to leave their tissue. When this happens the coral turns white because the zooxanthellae is also what gives them their color.
This graph shows the rise in CO2 and the decrease in the pH level in the ocean. Majority of the carbon dioxide in the air dissolves into the ocean. So as the level of carbon dioxide in the air increases, more of it dissolves into the ocean, causing the pH level to decrease, making the ocean become acidic. Because off all this acid, the corals cannot absorb the calcium carborate that they need to maintain their skeletons.
Climate change also causes physiological stress to the reefs. In the summer a disease called the "white band disease" starts to spread. This disease starts at the base of the colony and works its up way up to the tips, tearing off tissue of the coral skeleton. this disease is known to cause huge changes to placement and structure of the reefs.
This picture shows what the black-band disease looks like. This particular disease starts to spread during cold winters. This disease is different from the white-band because it "consumes" the surface of the colony leaving bare skeleton. The bacteria in this disease is what gives it the black color.