The devastation persists. The longest-running coral bleaching event in history, which has impacted reefs across the globe, will continue into 2017, according to a troubling forecast from the US National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch.

The alert isn’t as severe as in recent years after average sea surface temperatures have cooled following a significant El Niño phase.

But after years of stress from record ocean temperatures, the latest wave of warm water hits reefs that are vulnerable to further, potentially irreversible damage.

Already, Australia’s Great Barrier Reef is witnessing terrible bleaching and worse could still come during the antipodean summer.

The previous two years pushed reefs in nearly every tropical island group in the world to the brink and notoriously brought marine scientists to tears as they inspected the key ecosystems in Australia. inevent has shocked many coral reef scientists, with lots of locations being bleached two years in a row.

The episode began in late 2014 when El Nino fueled waters spilled out of the Pacific and spread around the world—heating up already warm ocean temperatures to record highs.

The warm water stresses a symbiotic relationship between coral polyps and the colorful algae for which they are known.

What is for certain is that the impact of the bleaching on small island economies, which rely heavily on vibrant reefs to support marine life and fisheries as well as for tourism.

Once a reef structure is lost, it may never recover, at least not in our lifetimes.