Australia: Great Barrier Reef – Affected by coral whitening

Terry Hughes bears bad news: A coral expert at James Cook University in Australia has been warning of the Great Barrier Reef rising for years. The results of his recent study show that the world’s largest coral reefs, spread over 2,300 kilometers off the northeast coast of Australia, contain more than 3,000 individual reefs and 1,500 species of fish and 400 species of coral.

Thus, only 2 percent of the Great Barrier Reef has not been affected by the five major bleaches since 1998. Since 2016, 80 percent of individual rocks have been whitewashed one, two or even three times. New study It was published in the journal “Current Biology”.

Bleaching is triggered by increased water temperature and thus by climate change. During bleaching, the coexistence of synodarians with a type of algae that energizes the corals and gives them their bright colors is disrupted. Although animals can recover from bleaching, if it lasts too long or happens too often, the corals will often die completely.

Dramatic results

For the current study, researchers studied five ocean heat waves over the past three decades: 1998, 2002, 2016, 2017 and 2020. In doing so, they discovered that the Great Barrier Reef was transformed into a “whitened chessboard”. Rocks, ”like Hughes In an article Wrote in the educational journal “Conversation.”

“Whether we want the Great Barrier Reef to be more active in the coming decades depends on how much we allow global warming,” the researcher says. “The bleaching events we have seen in recent years are the result of 1.2 degrees of global warming from pre-industrial times.” Hughes commented on the findings on Twitter: “It was one of the most dramatic results of my career.”

Sean Connolly, a biologist at the Hughes and Smithsonian Institution, made a direct appeal to government and government leaders attending the UN Climate Summit in Glasgow, Scotland, over the weekend. They must fulfill more ambitious promises and drastically reduce greenhouse gas emissions.

“This is essential for the future of coral reefs and for the hundreds of millions of people who depend on them for their livelihood and food security,” the scientists said. If warming is limited to 1.5 degrees, the rocks are believed to be able to survive.

Heat waves also harden

But another finding of the study is that each year the most dangerous patches remain unpainted for ten years or more. Conversely, if multiple episodes were close, the heat limit for intense whitening increased. Previous events have hardened parts of the Great Barrier Reef. For example, in 2002 and 2017, more heat was required to induce a level of bleaching similar to that measured in 1998 and 2016.

Meanwhile, 98 percent of the Great Barrier Reef’s personal reefs have been whitewashed since 1998. Only one group of rocks in the extreme south of the Great Barrier Reef remains unpolished, in a small area that is constantly cool in five mass bleaches.

Since 1990 the Reef has lost half of its coral reefs

In addition to climate change and heat waves in the oceans, rocks are also subject to other hazards: sediments from coal ports, sewage from agriculture, storms, and turbulent crown starfish have plagued coral reefs for years.

In October 2020, another study by James Cook University found that the number of small, medium and large corals in the Great Barrier Reef had dropped by more than 50 percent since the 1990s. It has already shown that even the enormous size of the rocks is not enough to ensure its survival. A report by the International Union for Conservation of Nature (IUCN) in December clarified the seriousness of the situation and classified the rocks’ potential as “important” for the first time. Nevertheless, in July UNESCO decided that the rocks should be classified as “not endangered”.