“The Net thrower”. The fisherman are conducting activities on Situgunung Lake. Photo location: Situgunung lake, Sukabumi, West Java, Indonesia. (Photo and caption by Dody Kusuma/National Geographic Photo Contest)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

A man photographs Anila Quayyum Agha's “Intersections” art work on the first day of ArtPrize at the Grand Rapids Art Museum in Grand Rapids, Mich. on Wednesday, September 24, 2014. (Photo by Emily Rose Bennett/AP Photo/The Grand Rapids Press)

Construction workers carry bricks on their heads near the country's parliament building in Naypyitaw November 11, 2014. Yangon lost its status as Myanmar's capital in 2005, after the former military junta carved a new seat of government from a parched wilderness some 380 km (236 miles) to the north and called it Naypyitaw (“Abode of Kings”). (Photo by Damir Sagolj/Reuters)

A Siberian tiger cub is seen at the Hengdaohezi Breeding Center for Felidae on October 26, 2007 in Harbin of Heilongjiang Province, China. Established in 1986, the breeding center is one of the world's largest captive breeding base for Siberian tigers. Distributed throughout northeastern China, far eastern Russia and North Korea, over 400 Siberian tigers exist in the wild, approximately 20 in China. (Photo by China Photos/Getty Images)

Indigenous women from the Kamayura tribe take part in a demonstration of Huka Huka fight at the first World Games for Indigenous Peoples in Palmas, Brazil, October 29, 2015. (Photo by Ueslei Marcelino/Reuters)

Iran's Hanieh Rajabi performs during the women's Daoshu competition at the 13th Wushu World Championships in Jakarta, Indonesia, Monday, November 16, 2015. (Photo by Tatan Syuflana/AP Photo)

A child looks at window cleaners work while dressed in sheep (C) and monkey costumes, denoting animal signs of the Chinese zodiac calendar, during an event marking the upcoming end of the year at a hotel in Tokyo, Japan, December 21, 2015. According to the zodiac calendar, 2015 is the year of the sheep and 2016 is the year of the monkey. (Photo by Thomas Peter/Reuters)