Climate modes can be leveraged to forecast coral bleaching months in advance

The increasing frequency of coral bleaching events, fueled by ocean warming, is driving development of management strategies aimed at minimizing impact and maximizing reef recovery. Accurate early bleaching forecasts could provide the lead time critical for effective planning and intervention, yet existing predictors rely on near-term thermal stress detection with limited accuracy. Here we show that 10 of the 11 bleaching events recorded on the southern Caribbean island of Curaçao since 1990 occurred in years when three large-scale Pacific and Atlantic climate modes aligned, compounding the long-term warming trend to drive reef temperatures above bleaching thresholds. Using climate mode indices available months prior to peak bleaching, we develop the Bleaching Event Early Predictor, a mode-based risk assessment tool that provides 5–6 months of lead time for management action. Although developed for Curaçao, this framework is likely adaptable across reef systems, offering a pathway towards seasonal prediction of bleaching risk. Coral bleaching at Curaçao occurs when large-scale climate modes align to compound the effects of ongoing warming; according to a new mode-based risk assessment tool which shows that these alignments can predict bleaching months in advance.