There are 60 recorded episodes of coral bleaching since 1979. It's claimed, at Wikipedia, that "Above-average sea water temperatures caused by global warming is the leading cause of coral bleaching".
How likely is that? That's a senseless statement because oceans are, at most, a few tenths of a degree warmer now than in the Little Ice Age of the 17th century. The average ocean temperature today is far lower than in the past (by as much as 16C). Why didn't corals all die off 55 million years ago?, when it was up to 16C warmer, on average than today. Or die off a few ten thousand years ago when oceans were about 6C colder than now?
During the deep glaciations, lasting most of the last 2.45 million years of Ice Age, ocean temperatures fell about 6C below today's. In the Paleocene–Eocene Thermal Maximum, around 55 million years ago, a warm period lasted for about 200,000 years when average global temperatures increased by 5–8 °C. When that began, temperatures were 8C warmer than now. So we're looking at peak warming 55 million years ago vs worst of the last glaciation. It shows average ocean temperature differences of 19 to 22 C warmer (at peak Eocene) than during the worst glaciation during the current Ice Age. Would you have me believe that massive temperature swings do not make corals extinct, but tiny swings less than a tenth of a degree do?
Problem with climate scare stories and propaganda is the science is never explained.