One hundred and fifty year old pictures of corals are rare enough, but these ones had the unmistakable pure white cauliflower look that marks them as totally bleached. But in 1862 the first coal fired power plant was still twenty years away from starting work as a coral destroyer, and carbon dioxide levels were a perfect 286ppm.

This is the spot (below) in the Northern Red Sea just at the end of "The Little Ice Age". Perhaps the seas were too alkaline then, and were yet to reach the perfect pH nirvana they must have struck the year before humans started scuba diving en masse.

We can see why scuba diving was not popular in 1862.

Somehow the great marine-psychics of the world know that corals didn't bleach in the early 1960's even though, or perhaps "because", there was almost no one down there to see it.

From Peter Ridd:

Reef-scientists often claim that coral bleaching is a new phenomenon that only started in the 1970's due to climate change. But a remarkable new paper published by Tomas Cedhagen, of Aarhus University in Denmark has uncovered a very early lithograph showing bleaching in 1862.