One of the many consequences of global warming, the fight against which will be discussed at the UN climate conference in Sharm el Sheikh from the beginning of November, is the bleaching of corals that can be observed in many places. Along the coast of host country Egypt is a coral reef that is colorful and still largely intact. According to scientists, in a few years it could remain the world’s only intact coral reef – thanks to a climate memory of its corals.
“We have solid evidence that this coral reef gives humanity hope for conserving a coral ecosystem,” says Mahmud Hanafy, a marine habitats expert at Suez Canal University. Because the corals off Egypt’s coast in the Red Sea are “very tolerant of the warming of the water”.
In the years 2009 to 2018 alone, 14 percent of the world’s coral reefs were destroyed by climate change. The Red Sea reef accounts for five percent of the world’s coral resources. More than global warming, other human threats are troubling him: mass tourism and overfishing.
Corals cover only 0.2 percent of the world’s seabed. Nevertheless, they are home to at least a quarter of marine plant and animal species. More than 500 million people depend on the corals: because they provide fishermen with a living, attract tourists and protect coastal areas from erosion.
The Intergovernmental Panel on Climate Change (IPCC) warns that if global warming continues, there will be no corals at least in the shallower waters by the end of the century. Even if the goal of the Paris climate agreement of 2015 to limit global warming to 1.5 degrees by 2100 compared to the pre-industrial age is met, most of the world’s coral populations are unlikely to survive because of the increasing heat waves in the world’s oceans.
This summer alone, 91 percent of Australia’s Great Barrier Reef was affected by coral bleaching due to one such heat wave. Bleached corals may recover depending on the severity of the damage. However, they do not survive repeated heat waves.
In Egypt, the corals seem to defy this rule. The reason: “A biological memory that developed in the course of evolution,” says Eslam Osman of King Abdullah University in Egypt’s neighboring country Saudi Arabia.
Osman and other researchers discovered that coral larvae entered the Red Sea from the Indian Ocean via the Gulf of Aden at the end of the last ice age 12,000 years ago. They had to pass “very warm waters” that would have acted like a filter. Only coral larvae that survived up to 32 degrees warm water got into the Red Sea.
Coral bleaching from marine heat waves has already occurred in the warmer waters of the Red Sea off the coast of Sudan. Further north off Egypt’s coast, however, the corals could tolerate a “temperature rise of one, two or even three degrees,” says Osman.
Precisely because the corals in the Red Sea are more resistant than elsewhere, they must be protected against other dangers, Hanafy demands. The Egyptian Ministry of the Environment must protect the entire 400 square kilometer coral reef. This would mean limiting both fishing and diving on the reef, and with it pollution of the waters around.
Osman also sees a precious treasure in Egypt’s corals and warns: “The north of the Red Sea must absolutely be preserved as one of the last protection zones for corals because this area could serve as a breeding ground for regeneration projects in the future.”
