Coral reefs will completely disappear in 30-40 years

Australian professor Peter Sale from the United Nations Institute for Water, Environment and Health published a book, “Our Dying Planet,” in which he predicted a very unsightly future for us and our descendants.

In addition to the usual things - climate change for the worse, ocean acidification, depletion of fish stocks, environmental pollution and the spread of "dead zones" in coastal waters - the author believes that by the end of the century (perhaps in 30-40 years) coral reefs will completely disappear. This will be the first ecosystem destroyed by man, the scientist emphasizes. People have already been born who will live in a world devoid of corals.

"We are creating a situation where the organisms that build coral reefs will either disappear or become extremely rare," the expert writes. "Because of this, they will not be able to build the structure we call a reef. And we have been working to destroy them for many years."

Coral reefs are a vital link in biodiversity. They are home to every fourth marine species, although they occupy only 0.1% of the area of the World Ocean. In terms of the number of species per unit area, they are even more diverse than tropical forests.

Recent studies have also shown that if corals die, medicine will lose many useful substances. For example, a new method of treating leukemia based on a sponge that lives in reefs was announced a few months ago. Compounds that can serve as a powerful sunscreen have also been found in corals.

And the economic value! Firstly, fish. Secondly, tourism. About 850 million people live within 100 km of reefs, and about 275 million of them depend on reefs for food and livelihood. Reefs also protect low-lying islands and coastal areas from extreme weather conditions by absorbing waves.

Carbon emissions from human activities are the main cause of the expected decline. First, the greenhouse effect increases ocean surface temperatures (they have risen by 0.67˚C in the last century). This causes the photosynthetic algae that provide energy to the corals to disappear, causing them to bleach and then die within weeks.

Second, water oxidation occurs. About a third of the carbon dioxide we put into the atmosphere is absorbed by the ocean surface. As it has recently become clear, this process makes it more difficult for reef organisms to extract the compounds needed to build carbon skeletons from the water.

Mr Sale, however, forgets to make an important caveat about the remarkable resilience of corals (if our data on previous mass extinctions is to be believed). “There have been periods of reefs and periods of no reefs, despite the fact that reef-building creatures have been around for hundreds of millions of years,” says Mark Spalding of the University of Cambridge in the UK. “When the climate allows, they build their fantastic structures; when it doesn’t, they bide their time as unremarkable invertebrates.”

It’s worth noting that reef loss has usually preceded mass extinctions. The author ominously calls them the ecological equivalent of a canary in a coal mine. Around 20% of coral reefs have died in recent decades. Mass bleaching is a relatively new phenomenon: scientists have been monitoring corals since the 1950s, but it wasn’t until 1983 that this was noticed. “In 1998, I witnessed literally 80-90% of the coral reefs in the Seychelles die in a matter of weeks,” Mr. Spalding recalls with horror. That episode alone led to the disappearance of 16% of the planet’s corals.

Mr Sale notes that subsequent mass coral die-offs in 2005 and 2010 were not as dramatic simply because there was so little coral left.

These dramatic episodes coincide with unusual weather conditions (such as El Niño), meaning they can be the result of natural causes, but due to climate change they are now occurring more frequently and with more serious consequences. In short, the fight against global warming is an urgent matter. Under no circumstances should the concentration of carbon dioxide in the atmosphere be allowed to exceed 450 parts per million. Today, this figure is around 390 parts per million, and many experts believe that the “500” mark will be surpassed quite soon.

Local efforts can also help. Alex Rogers of the University of Oxford in the UK says: “We know for sure that if we stop overfishing and pollution, corals will have a much better chance of recovering. But that won’t save them – it will just buy us a little time if climate change continues at its current rate.”

While not all scientists agree with the timeframes the book suggests, the crisis is clear. “When you talk about ecosystem collapse within a human generation, that’s just a figure of speech,” says Mr. Rogers. “But the idea is right: People don’t understand how fast things are changing.”

[ 1 ], [ 2 ]