A reef shell lies on a beach as the sun sets on Lady Elliot Island located north-east of the town of Bundaberg in Queensland, Australia, June 10, 2015. UNESCO World Heritage delegates recently snorkelled on Australia’s Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was “poor”. (Photo by David Gray/Reuters)

Young girls take ballet lessons at the New Dreams dance studio in the Luz neighborhood known to locals as Cracolandia (Crackland) in Sao Paulo, Brazil, August 14, 2015. For the young girls learning to jump and plie, the dance studio provides a way forward and out of the difficult environment they have grown up in. Brazil is one of the world's highest consuming countries of crack cocaine, and Cracolandia, or “Crack Land”, located in the outskirts of Sao Paulo, is one of the most intense and brutal hubs. (Photo by Nacho Doce/Reuters)

A journalist operate a harness with multiple recording devices capable of recording and live streaming outside the Great Hall of the People where the opening session of the Chinese People's Political Consultative Conference (CPPCC) was held in Beijing, China, Friday, March 3, 2017. Thousands of delegates have gathered at the Chinese capital for the opening of the annual session of the Chinese People's Political Consultative Conference, which advises the rubberstamp parliament, whose annual session begins Sunday. (Photo by Ng Han Guan/AP Photo)

The possible surface of TRAPPIST-1f, one of seven newly discovered planets in the TRAPPIST-1 system that scientists using the Spitzer Space Telescope and ground based telescopes have discovered. (Photo by Reuters/NASA/JPL-Caltech)

A baby elephant eats in a swamp in Amboseli national park, Kenya, March 19, 2017. (Photo by Goran Tomasevic/Reuters)

A Pakistani labourer carries bricks on his back at a construction site at a residential area in Islamabad on March 29, 2017. (Photo by Aamir Qureshi/AFP Photo)

The Doppler on Wheels (DOW) vehicle scans a supercell thunderstorm during a tornado research mission, May 8, 2017 in Elbert County near Agate, Colorado. Doppler on Wheels (DOW) is a mobile doppler radar mounted on a truck that brings instruments directly into storms, allowing scientists to scan storms and tornadoes and make 3-D maps of wind and debris. (Photo by Drew Angerer/Getty Images)

Actress Laetitia Casta attends the “The Meyerowitz Stories” screening during the 70th annual Cannes Film Festival at Palais des Festivals on May 21, 2017 in Cannes, France. (Photo by Stephane Mahe/Reuters)