Coral bleaching – level 3
These aerials of Australia's Great Barrier Reef are evidence the most untouched part of it has the most severe bleaching in its history. The footage, which filmed over 500 coral reefs during six days from Cairns to Papua New Guinea, shows 95% are white and yellow.
Scientists say the bleaching happens in rising water temperatures – the coral, under stress, drives out living algae, causing it to calcify, and part of that is down to the current El Niño climate cycle. They say unless the World Heritage Site gets a break in the weather conditions within weeks, some coral areas are unlikely to survive. But the World Meteorological Organisation says a break in temperatures is unlikely, as this year looks set to be the hottest on record.
The Great Barrier Reef stretches 1,200 miles (1,931 kilometres) along Australia's northeast coast and is the world's largest living ecosystem. Last May, the World Heritage Committee stopped short of placing it on an "in danger" list but this latest find may raise long-term concerns about its future.
Difficult words: aerial (a video taken from the air), bleaching (getting white), footage (a video), singular alga, plural algae (a simple, non-flowering aquatic plant), calcify (to harden with calcium), be down to (because of), stretch (to exist over an area), stop short (to stop suddenly).
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