Masks that come with T'antawawas bread are displayed in a popular market of La Paz, October 27, 2015. Residents of La Paz city have started to prepare offerings for their dead relatives next Sunday as part of the All Saints' Day celebrations. The offerings include things the deceased liked during their life, such as fruits, food, breads and drinks, according to local media. (Photo by David Mercado/Reuters)

South Asian countries in terms of total contribution of travel and tourism to GDP. #6. Vietnam, Total GDP: USD 202.6 billion (2016). Contribution of Travel and Tourism to GDP: 9.1% . Here: A boat in the Thu Bon River, Hoi An, Vietnam. (Photo by Domingo Leiva/Getty Images)

An adult helps a young girl light a cigarette as a band plays in the background in the village of Vale de Salgueiro, northern Portugal, during the local Kings' Feast Friday, January 5, 2018. The village's Epiphany celebrations, called Kings' Feast, feature a tradition that each year causes an outcry among outsiders: parents encourage their children, some as young as 5, to smoke cigarettes. (Photo by Armando Franca/AP Photo)

Irwan bathes a domesticated crocodile at his house in Bogor, Indonesia on January 22, 2018. Irwan found it as a baby and now it has been living with Irwans family for 20 years. Indonesia is known as a hotbed of exotic pet domestication and trade. People have been known to keep endangered animals such as slow lorises, eagles and pangolins, angering conservationists and animal rights activists. (Photo by Eko Siswono Toyudho/Anadolu Agency/Getty Images)

This Wednesday, August 31, 2016 photo, provided by the Syrian anti-government activist group Aleppo Media Center (AMC), shows Syrian boys dive into a hole filled with water that was caused by a missile attack in the rebel-held neighborhood of Sheikh Saeed in Aleppo province, Syria. (Photo by Aleppo Media Center via AP Photo)

In this October 8, 2017, photo, Emily Lynch reacts to hitting her first clay target during a training session for the Trigger Warning Queer & Trans Gun Club in Victor, N.Y. A gay, lesbian and transgender group concerned that extremists have become more emboldened and dangerous have decided to take up arms. The gun club meets once a month to shoot long guns in a field in upstate New York. (Photo by Adrian Kraus/AP Photo)

A hyena cub got a mouthful from his mum after it appears he got a right telling off. Michael Raddall, a animal enthusiast and wildlife photographer from South Africa, snapped the mum and cub at the Timbavati game reserve in South Africa while on safari at the Umlani Bush camp. (Photo by Michael Raddall/Caters News Agency)

The Greenland ice sheet is a vast body of ice covering 660,235 sq miles, roughly 80% of the surface of Greenland. It is the second largest ice body in the world, after the Antarctic Ice Sheet. Some scientists predict that climate change may be near a "tipping point" where the entire ice sheet will melt in about 2000 years. If the entire 2,850,000 cubic kilometres (683,751 cu mi) of ice were to melt, it would lead to a global sea level rise of 7.2 m (23.6 ft).