When Mariya Galochkina and her team at the Woods Hole Oceanographic Institution analyzed the skeletal remains of massive reef-building corals from Curaçao's shores, they discovered something that could transform how we protect the world's most vulnerable ecosystems: the story of bleaching written in stone, readable months before it happens.
Coral bleaching is escalating across the Caribbean as ocean temperatures continue to climb. When corals become stressed by unusual warmth, they expel the microscopic algae that gives them color and energy, often leading to death across entire reef systems. On Curaçao alone, coral reef tourism and fisheries contribute hundreds of millions of dollars annually to the island's economy, yet the reefs that sustain this livelihood have declined dramatically in recent decades. The crisis is urgent, and the window for action has been vanishingly small—until now.
Researchers at WHOI have developed a groundbreaking early-warning tool called the Bleaching Event Early Predictor, or BEEP, that can forecast coral bleaching five to six months in advance. The breakthrough appears in a new study published in Communications Earth & Environment. By examining CT scans of 44 coral cores collected from Curaçao's reefs, Galochkina and her colleagues reconstructed a 72-year bleaching history spanning 1950 to 2022. They found that significant bleaching on Curaçao began only around 1990, and since then, it has occurred in years when three large-scale climate patterns align in specific ways: Atlantic Multidecadal Variability, El Niño–Southern Oscillation, and North Atlantic Oscillation. When these climate modes combine, they weaken regional winds and reduce cooling from upwelling currents, allowing reef temperatures to climb above bleaching thresholds.
The innovation lies in looking far beyond the usual approach. Existing bleaching forecasts track heat stress in near-real time, but they often miss the mark or arrive too late for managers to respond. BEEP inverts this logic by monitoring large-scale climate patterns months before peak summer heat, giving reef managers crucial time to act. This five-to-six-month advance warning is transformative: managers can move coral fragments from in-situ restoration nurseries to cooler areas of the reef, or relocate them entirely to land-based nurseries if bleaching is forecast.
"Existing bleaching forecasts track heat stress in near-real time, and also rely on generalized thresholds for predicting bleaching risk, which means they often do not provide reef managers and restoration practitioners with enough lead time to prepare and respond effectively, or the predictions are inaccurate," Galochkina explained in the study. "We take a different approach by using large-scale climate patterns that interact to shape regional ocean and atmosphere conditions with a time lag, which lets us identify bleaching risk months in advance."
The research exemplifies how fundamental science can be translated into solutions for real-world challenges. Anne Cohen, senior scientist at WHOI and co-author of the study, credits decades of investment in Earth-system monitoring and satellite data, much of it freely available to researchers. While BEEP currently focuses on Curaçao, the tool could potentially be adapted for coral reefs across the Caribbean and other tropical regions where climate modes similarly influence local ocean conditions. For island communities whose survival depends on reef health, this new predictive power offers something that has been rare in recent years: hope, and a genuine opportunity to act before disaster strikes.