The effects of climate change are alarming: coral reefs worldwide are suffering from massive bleaching. Experts warn of a global catastrophe.
Frankfurt – Global warming and its effects can no longer be overlooked. They manifest themselves in the form of record temperatures during the winter months, floods and fires in countries such as Australia and Greece. The oceans, which are suffering from the consequences of climate change, are particularly affected. Although these effects are not always obvious, experts have been warning about them for some time. Now a recent report from the US National Oceanic and Atmospheric Administration (NOAA) suggests that we are on the path to a global catastrophe.
Coral bleaching is progressing much faster than expected
The conditions in the world's oceans are of great concern to researchers, particularly massive coral bleaching. According to US researchers, we are experiencing a phase of intense coral bleaching for the second time in a decade.
NOAA's Derek Manzello reports: "Significant coral bleaching was documented in both the Northern and Southern Hemispheres of every major ocean basin from February 2023 to April 2024." More than half of all colorful coral areas in the oceans have been affected by bleaching and have turned “into a ghost landscape.” This situation was originally only predicted by marine researchers for the year 2030.
“More common and more serious”: Rising water temperatures responsible for coral bleaching
Coral bleaching is a direct result of rising water temperatures, which cause corals to reject the algae that live within them. However, these algae are the corals' main food source, leading to a loss of color and ultimately a threat to the survival of these cnidarians.
NOAA bases its findings on satellite measurements and so-called heat stress levels recorded since 1985. The current global coral bleaching event is the fourth since records began and the second in ten years. Experts had already warned about this phenomenon in 1998, 2010 and 2016. Coral reefs in the Indian Ocean, the Pacific and the Atlantic are particularly affected. Affected regions include the well-known Great Barrier Reef in Australia, the Seychelles and larger areas of the South Pacific, such as the corals off the Fiji Islands. As global warming continues, “coral bleaching events are becoming more frequent and severe,” Manzello said.
Too little recovery time for corals – “tipping point exceeded”
However, coral bleaching is not necessarily a death sentence for the corals. They can recover after bleaching, provided water temperatures fall and other stressors such as overfishing and marine pollution are reduced. However, due to the increasing frequency of bleaching, the corals do not have enough time to recover.
Marine researchers who have already warned of warming in the Baltic Sea have found that recovery could take seven to 15 years. “A realistic assumption is that we have passed a tipping point for coral reefs,” says a researcher from Kenya. According to him, the corals are in a “downward spiral that cannot be stopped” if CO₂ emissions are not drastically reduced.
Coral reefs have many important functions - projects have been launched to save them
Corals are not only important for tourism, they also play an important role in fish biodiversity. They provide protection and food for other marine animals such as fish, crabs and sea urchins. A coral die-off can therefore have an impact on fish stocks worldwide. In addition, coral reefs protect coastal areas by slowing down strong currents in the sea that can lead to storm surges.
There are already projects to save corals, for example in Florida. Measures were taken there and “significant progress” was made after the extreme heat wave in 2023. The coral reefs were moved to deeper, cooler waters and parasols were used to protect the corals from bleaching. The researchers are calling for global measures for coral restoration in the face of climate change.