“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 lies in the sea grass at a beach on July 18, 2016 in Qingdao, Shandong Province of China. The enteromorpha prolifera spread on the beaches in Qingdao and were under clearing. (Photo by VCG/VCG via Getty Images)

A woman mourns the loss of her husband, next to a placard which reads “I'm a pusher”, who was shot dead by an unidentified gunman in Manila on July 23, 2016. Philippine President Rodrigo Duterte swept to power in May on a promise to clampdown on drugs, and police have since confirmed killing nearly 200 people in a two-month crime blitz. There has also been a surge in killings by anti-drug vigilantes who leave victims' corpses on city streets wrapped in packaging tape with signs accusing them of being drug dealers. (Photo by Noel Celis/AFP Photo)

A jockey takes part in a traditional cattle race or “Pacu Jawi”, to mark the end of the rice harvest in Tanah Datar, West Sumatra, Indonesia, August 13, 2016 in this photo taken by Antara Foto. (Photo by Hafiz Mubarak A./Reuters/Antara Foto)

A man takes a picture of models as they pose next to Cosmis Racing Wheels products during the 2016 Moscow International Auto Salon in Moscow, Russia, August 26, 2016. (Photo by Sergei Karpukhin/Reuters)

Chinese models with animal-themed body paintings pose during a campaign for animal protection at Sanya Color Zoo in Sanya city, south China's Hainan province, 10 January 2016. The girls wearing strapless bras and short pants only were colored with animal-themed paintings such as zebra, cheetah, tiger and peacock. They paraded throughout the newly-opened Sanya Color Zoo and met visitors to take pictures, causing envies from netizens living in north China who are suffering chills. (Photo by Imaginechina/Splash News)

Germany's Angelique Kerber reacts after popping a bottle of champagne, a day following her win in the final match at the Australian Open tennis tournament, at the Government House in Melbourne, Australia, January 31, 2016. (Photo by Issei Kato/Reuters)