Last summer, the Caribbean experienced a major bleaching event of its stony corals believed to be a direct result of warming water temperatures. Colonies of Elkhorn corals were some of the worst hit, but all stony corals suffered. In some places, 40% of the corals died. Since this occurs underwater, many people never see or hear about this, but if you want an analogous situation, imagine 40% of the trees in Yellowstone National Forest--especially those that are a hundred years old or more (as many of the dead and dying corals are)--dying in one summer. The people would take note, no?
Researchers have been clamoring over this major bleaching event since it was first discovered last summer, but the mainstream press has said very little about it, due in part to the fact that the Caribbean is a major tourist spot and the island governments don't want toursits to think anything has changed. But not only has it changed, this summer (if current water temperatures are any indication) looks to be just as bad.
You can read about it here.