A situation that marine researchers had only expected to occur in 2030 has now already occurred: a large proportion of the world's coral reefs are suffering from climate change and are threatened with extinction.
Washington – Record temperatures in the winter months, floods and fires in countries like Australia and Greece: the effects of climate change can already be felt in many areas of life. The world's oceans are particularly suffering from global warming. Even if these consequences are not necessarily visible, experts have been warning about them for a long time. Now a new report from the US ocean agency NOAA (National Oceanic and Atmospheric Administration) warns of a global catastrophe.
Massive coral bleaching: Researchers concerned about conditions in the world's oceans
According to US researchers, we are already in a phase of massive coral bleaching for the second time in ten years. “Significant coral bleaching was documented in both the Northern and Southern Hemispheres of every major ocean basin from February 2023 to April 2024,” said Derek Manzello of NOAA. More than 54 percent of all otherwise colorful coral areas in the oceans have been affected by bleaching caused by global warming and have been transformed “into a ghost landscape”. Marine researchers actually only predicted this point for 2030. As the water temperature rises, the corals shed the algae that live within them. However, these are the primary source of food for corals, which leads to a loss of color and consequently endangers the lives of the cnidarians.
For these findings, NOAA evaluated satellite measurements and so-called heat stress levels from 1985 to the present. The current global coral bleaching event is the fourth since records began and the second in ten years. Experts previously warned in 1998, 2010 and 2016. The current phase particularly affects coral reefs in the Indian Ocean, the Pacific and the Atlantic. The list of affected regions is long: Examples include the well-known Great Barrier Reef in Australia, but also the Seychelles or 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 in the study.
Hope for coral reef recovery? According to marine researchers, the tipping point may have been passed
But coral bleaching does not mean a death sentence for the animals, the report also says. Because corals can recover after bleaching. To do this, water temperatures must fall and other stress factors for corals such as overfishing and ocean pollution must be reduced. However, due to further bleaching, the corals do not have enough time to recover. In previous bleaching events, marine researchers who had already warned of warming in the Baltic Sea found that recovery could take around seven to 15 years. “A realistic assumption is that we have passed a tipping point for coral reefs,” says a researcher from Kenya. The corals are in a “downward spiral that cannot be stopped” if CO₂ emissions are not drastically reduced.
Biodiversity, coastal protection, tourism: This is why corals should be protected from climate change
Corals are not only an important source of income for regional tourism for divers and snorkelers. They also have an impact on fish biodiversity, the researchers write. In them, other marine animals such as fish, crabs and sea urchins not only find protection, but also a source of food. Coral death can therefore have an impact on fish stocks worldwide. In addition, coral reefs have a protective function for coastal areas, as they slow down powerful currents in the sea that can, for example, result in storm surges. German coasts are also changing drastically due to climate change.
There are projects to save corals in Florida, for example. Measures have already been taken there and “significant progress” made after the extreme heat wave in 2023. For example, the coral reefs were relocated to deeper, cooler waters. Umbrellas for the reefs are also said to have helped protect coral reefs from bleaching. The researchers call for global action to advance coral restoration in the face of climate change.
(nbe)