The Great Barrier Reef should be put on a list of World Heritage Sites that are "in danger", says UNESCO. UNESCO's World Heritage Committee recommended the listing, recognizing the destruction of the world's largest coral reef. The committee is also urging Australia to take "accelerated action" on global warming. But the Australian government said it would "strongly oppose" the recommendation and argued the reefs are best managed. Spanning nearly 345,000 square kilometers, the reef is home to more than 1,500 species of fish . It also contributes $4.8 billion annually to Australia's economy, according to the Great Barrier Reef Foundation. But the reef has suffered from three devastating mass bleaching events since 2015 and this is caused by above-average ocean temperatures as the burning of fossil fuels heats up the planet.The Australian government is said to have invested $3 billion in reef protection but the UNESCO report says despite efforts by the Australian government, key targets on improving water quality in the reef had not been met. The inclusion will be voted on at the committee's meeting in China next month. Listing a site as "in danger" can help address threats but can also affect the tourism sector of the country harshly.