Global warming has targeted the coral reefs in Australia once again within a span of five years. The Great Barrier Reef GBR is in the grip of a third mass coral bleaching event. The last such outbreak happened in 2016 and 2017 and it destroyed nearly half of the shallow water corals. The GBR is the world’s biggest reef system and it is in danger. Prof Terry Hughes of James Cook University is an expert in coral reef studies and he carried out a detailed study on the subject. He conducted an aerial survey over hundreds of individual reefs and told a section of the media, “We know this is a mass bleaching event and it’s a severe one.” He went on to add that the current level of bleaching is more severe than in 1998 and 2002.

How it compares with the bleaching of 2016 and 2017 is yet to be established.

The Guardian says the professor, working with those associated with looking after the Great Barrier Reef, conducted the survey using a spotter plane. He flew it at a low altitude to assess the extent and severity of bleaching. It is a result of global warming because of greenhouse gases and is considered a major threat to the ecosystems of coral reefs. Incidentally, not all bleached corals die. The bleaching occurs when they remain in warm waters for a long time. Recovery is possible when temperatures drop, else they perish.

Bleaching of coral reefs more in shallow waters

The UN’s Intergovernmental Panel on Climate Change predicts loss of majority of tropical coral reefs even if the global heating was restricted to 1.5C. If the temperature was maintained at 1.2C the reefs would be “at very high risk.” In this context, it is worthwhile to note that the world has already warmed about 1C since the industrial revolution.

Hence, rise in global temperatures would harm the coral reefs.

The Guardian quotes Hughes who says the effect of coral bleaching on popular tourist spots between Cairns and the Whitsunday Islands was not much.

The nature of bleaching there was mild and they could recover in due course of time. However, some juvenile corals had bleached in the central part of the reef. A report by the authorities observes that the reef’s outlook needs to be improved. The Great Barrier Reef is a UNESCO World Heritage site and the back-to-back mass bleaching events could come in for scrutiny.

Global warming threatens Australian coral reefs

According to NBC News, the Great Barrier Reef in Australia is a Travel destination. It faces another round of widespread coral bleaching event. Scientists assign this to rise in global temperatures coupled with corresponding warmer oceans. These are threats to the fragile corals. The current bleaching is the third such event in the past five years.

It has the experts worried. They say heat-induced bleaching is natural but climate change has increased the frequency of occurrences and the corals are denied time to recover and grow back. Prof Terry Hughes says, "The gap between one event and the next is shrinking, not just for the Great Barrier Reef, but reefs throughout the tropics.” He adds that recovery takes time. It takes around a decade for even the fastest-growing corals and could take much longer for the slow-growing ones.

Coral reefs are a part of the ocean ecosystem

The Great Barrier Reef is a designated World Heritage Site. It is also an integral part of the ocean ecosystem. NBC News says the GBR covers a vast area that stretches for almost 1,500 miles off the coast of Queensland.

It is habitat of a wide variety of marine life like fish, turtles, mollusks etcetera. Coral bleaching is a result of abnormal conditions of the water. One of these is the fluctuation in ocean temperatures, another is when ocean water turns more acidic. Such environmental stress makes the corals lose their attractive colors and become ghostly white.