Coral Bleaching in Space and Time

Abstract

Widespread coral bleaching and subsequent mortality have been clearly linked to elevated sea surface temperatures. As ocean temperatures continue to increase in relation to the bleaching thresholds of corals, it has been predicted that the frequency and severity of coral bleaching will increase. This chapter analyses a comprehensive database of coral bleaching records to describe spatial and temporal patterns of bleaching since 1979. Severe global-scale bleaching events have occurred on three occasions (1998, 2010, and 2014--2017), while additional possible events in 1987 and 1983 were also identified. All of these events were associated with a severe El Niño event. Although there has been an increase in the number of bleaching reports per year since 1983, the number of confirmed severe global events is currently too small to confirm or refute the hypothesis that the frequency of these events is increasing. However, there is growing evidence that low-level bleaching has increased to the point where most regions and ocean basins are reporting some coral bleaching every year. The available data cannot, at this stage, confirm the notion that the severity of bleaching events at a global scale is increasing.