Australisches Great Barrier Reef bedroht vom Klimawandel
The longest global coral bleaching event on record is underway due to record breaking ocean temperatures driven by climate change and El Niño. Australia’s iconic reefs, particularly the northern part of the Great Barrier Reef (GBR), are experiencing severe bleaching. Climate change – driven mainly by the burning of coal, oil and gas – has caused extreme ocean temperatures, making the bleaching on the GBR this year at least 175 times more likely. Australian scientists have recently revealed the full extent of the coral bleaching that is unfolding on the Great Barrier Reef, off the coast of Queensland. The final results of extensive aerial and underwater surveys reveal that 93% of the reef has been affected. It’s a mixed picture of very severe, moderate and little damage that changes dramatically from north to south along the 2300km length of the Reef.
There was already considerable murmuring that this event, which damages a famous World Heritage site and could deal a blow to a highly valuable tourism industry, did not simply happen by chance. And now, a near real-time analysis by a group of Australian climate and coral reef researchers has affirmed that the extremely warm March sea temperatures in the Coral Sea, which are responsible for the event, were hardly “natural.” At present rates of climate change, this level of bleaching could occur every two years by the 2030s. An estimated 36% of the world’s coral reefs have been affected by major bleaching and nearly all reefs have experienced some thermal stress. Climate change also threatens fish, crustaceans and other species that rely on the reefs as habitat.
The Great Barrier Reef is a multi-billion dollar economic asset. Its value-added economic contribution to the Australian economy was $5.7 billion in 2011-12, supporting 69,000 jobs. About 500 million people worldwide rely on coral reefs for their food and livelihoods, which represent an economic asset worth an astounding $1 trillion. Recovery could be impossible for many of the reefs currently affected by severe bleaching if climate change is not arrested. The future of coral reefs though, which are among the most biologically diverse and economically valuable ecosystems on Earth, depends on how much and how fast we reduce greenhouse gas emissions now and in the coming years and decades.