The White Barrier Reef

A team of Australian researchers completed a series of thorough aerial surveys of Australia's Great Barrier Reef last weekend.Their results confirm the fear: The Royal Reef, which is the largest of the world's reefs and which can also be seen from space, is currently going through the hardest coral bleaching in its history - 93 percent of the reef has already been damaged by the bleaching, at least partially.

Bleaching is caused when temperatures are higher than normal andHigh acidity of the water cause the corals to feel stress. The result is that colorful algae (zooxanthellae), which normally live with them in symbiosis and feed them with various nutrients created in the process of photosynthesis, leave. Her departure causes the coral to gradually turn white.

When the bleaching condition passes, assuming it hasn't been too long, the algae returns and restores the color to the coral, meaning it allows it to recover. If this does not happen within a short period of time, the coral bleaches completely and is unable to survive. In the surveys conducted by the team under the surface of the water, it became clear that in some parts of the reef about 50 percent of the corals affected by the bleaching had already died.

Significant reef bleaching events have occurred in the past, and not even that long ago: it happened in 1998 and 2010, but then large parts of the reef managed to recover from the bleaching and recover.

Unfortunately for the Great Barrier Reef, the world is currently in the midst of a longer-than-usual El Niño (The Boy, in Spanish). This is the name of a climatic phenomenon during which the temperature of the Pacific Ocean water rises west of Ecuador and Peru, which affects the water temperature in Australia as well. This phenomenon occurs once every few years and lasts about a month, but occasionally it is longer - and according to scientists, this is another result of global warming.

El Nino causes an abnormal warming of the water at the equator, and threatens reefs not only in Australia but around the world. The high temperatures do not allow the water to reach the heat that the reef can bear, and as a result many of the corals do not manage to return to themselves and their color in time and do not survive.

The Australian researchers say that the least affected areas are in the south of the reef, where rains fell during last March that helped cool the water. In the center of the reef the situation is not alarming, but the really bad news is the condition of the northern part - in this area 80 percent of the corals are in advanced bleaching, and the researchers are pessimistic about their ability to recover at this stage. Even in the smaller coral reefs on the west coast of Australia, 80 percent of the coral is in the process of bleaching.

What will be on the reef?

The Great Barrier Reef stretches for 2,300 km, and is home to thousands of protected species, some of which are local. Currently, only 7 percent of its area is not affected by bleaching, and the spectacular area until recently is becoming more and more like a coral graveyard. It is not clear how many of the creatures living there will manage to survive .

It is not just about the loss of species and magnificent habitats - tourism in the Great Barrier Reef employs about 70 thousand people, and brings in Australia about 20 billion NIS per year (5 million US dollars).

The researchers expect that in the coming months, as the water cools, parts of the damaged area will be able to recover to some extent. But as Terry Hughes, the leading researcher, put it: "The area will never return to the way it was, certainly not in my lifetime."