The Great Barrier Reef in Australia has long been one of the world’s most magnificent natural wonders. But huge sections of the Great Barrier Reef, stretching across hundreds of miles of its most pristine northern sector, were recently found to be dead, killed last year by overheated seawater.
The state of coral reefs is a telling sign of the health of the seas. Their distress and death are yet another marker of the ravages of global climate change.
If most of the world’s coral reefs die, as scientists fear is increasingly likely, some of the richest and most colorful life in the ocean could be lost, along with huge sums from reef tourism. In poorer countries, lives are at stake: hundreds of millions of people get their protein primarily from reef fish, and the loss of that food supply could become a humanitarian crisis.
Corals require warm water to thrive, but they are exquisitely sensitive to extra heat. Just 1 to 1.5 degrees Celsius of excess warming can sometimes kill the tiny creatures.
Globally, the ocean has warmed by about 0.8 degrees Celsius since the late 19th century, by a conservative calculation, and a bit more in the tropics, home to many reefs. An additional kick was supplied by an El Nino weather pattern that peaked in 2016 and temporarily warmed much of the surface of the planet, causing the hottest year in a historical record dating to 1880.
Bleaching indicates that corals are under heat stress, but they do not always die and cooler water can help them recover. However, recent surveys of the Great Barrier Reef documented that extensive patches of reef had in fact died, and would not be likely to recover soon, if at all.
Source article: http://www.taipeitimes.com/News/lang/archives/2017/04/23/2003669227