The highest probability of bleaching occurred 15-20 degrees north and south of the Equator, despite temperature levels there being similar to those at Equatorial sites. The researchers can't sat why this is, but suggest that it could be connected to the high diversity of Equatorial coral species, including types that are less susceptible to temperature change or more accustomed to warmer water.
Also revealed by the survey was that over the past decade coral-bleaching had occurred at temperatures around half a degree Centigrade higher than in the previous decade. This suggested that surviving coral populations were adapting to have a higher thermal threshold.
The results underline the need for better global modelling of the effects of climate change, say the researchers.
Their study is published in Nature Communications .