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A study earlier this year in the Proceedings of the National Academies of Science said the current extinction period, known as the Holocene extinction event, may be the greatest event in the Earth's history and the first due to human actions. Unlike previous events, however, extinctions are happening over the course of decades rather than centuries. Recent studies suggest that a quarter of the world's species may go extinct by 2050.
The UN warning accompanies an increasingly frequent round of sobering news about ecosystem failures. The latest global coral reef assessment estimates that 19 percent of the world's coral reefs are dead. Their major threats include warming sea-surface temperatures and expanding seawater acidification. Zooxanthellae, the tiny organisms that give coral reefs their vibrant colors, are emigrating from their hosts in massive numbers as oceans heat up, killing themselves and the coral they leave behind - a process known as coral bleaching.
The report, released by the Global Coral Reef Monitoring Network Wednesday at the international climate change negotiations in Poznań, Poland, predicts that many of the remaining reefs may disappear within the next 40 years if current emission trends continue.
"If nothing is done to substantially cut emissions, we could effectively lose coral reefs as we know them, with major coral extinctions," said Clive Wilkinson, the network's coordinator, in a press release.
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http://www.enn.com/wildlife/article/38850