Shortly before the visit of a UNESCO expert commission to find out about the state of the Great Barrier Reef in Australia, the responsible authority raises the alarm about a new coral bleaching on the world natural heritage site.

Above-average upper-sea temperatures in March put corals under "stress" leading to bleaching and, in worst-case scenarios, even dying, the marine parks agency's chief scientist David Wachenfeld said in his report on the reef's condition on Friday .

The authorities have therefore started to check the condition of the natural wonder from the air.

Till Fähnders

Political correspondent for Southeast Asia.

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So far, about half of the more than 2,300-kilometer-long reef system has been examined, initially in the central part that was particularly affected and in the far north, where the situation was particularly unclear.

"We have discovered extensive but variable bleaching in various regions," said Wachenfeld.

Impacts on the reef ranged from "minor to severe".

Experts fear another mass bleaching, the sixth overall and the fourth in just six years after 2016, 2017 and 2020.

fight against climate change crucial

The status report was published just days before a UNESCO delegation is due to visit Australia to find out about the condition of the reef and the government's efforts to protect it.

The government in Canberra wants to dissuade the UN organization from downgrading the reef as "endangered" because it expects such a classification to have negative effects on tourism, among other things.

Canberra describes the natural wonder as the "best managed" reef in the world.

The government has committed to investing $1 billion in reef protection over the next nine years.

However, environmentalists criticize the government's inadequate climate protection measures, which remain far below what is necessary to keep global warming below the target of 1.5 degrees Celsius.

Experts see global warming as a key factor in the recurring coral bleaching events on the world-famous reef system.

Australia is one of the world's largest per capita emitters of carbon dioxide and a leading coal exporter.

At the climate conference in Glasgow, the government in Canberra committed itself for the first time to achieving climate neutrality by 2050, but has stuck to its existing savings targets for 2030.

With better conditions, the reef could recover

The temperatures around the world's largest coral reef last week were between half a degree and two degrees, in some areas even up to four degrees above the usual March average, said Wachenfeld.

The problem has worsened since the beginning of the month, which is unusual for this time of year when Australia is entering autumn and getting cooler.

In addition, Australia is currently experiencing the effects of the La Niña weather phenomenon, which typically brings cooler temperatures, rain and cloud cover that could prevent coral bleaching.

In the case of bleaching, the corals lose their greenish-brown or variegated coloring when, under stress, they shed the algae with which they normally live in symbiosis.

As a result, the coral lacks nutrients.

Scientist Wachenfeld explained that bleached corals are still alive and could recover if conditions improve.

The worst-hit areas are currently outside of the city of Townsville.

In the tourist areas near Cairns and Port Douglas there is currently no serious damage to the corals.