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)

In this January 8, 2015 photo, a monk Kenmyo Muta bows at the condominium construction site and the gate of Sengakuji temple in Tokyo. The “47 ronin” samurai who inspired the long-loved saga of loyalty and honor eulogized in films, books and plays are fighting a new kind of battle in urban Japan. An apartment complex is going up next to the curved tile-roofed Sengakuji temple where the three-century-old graves of the ronin, or masterless samurai, lie. The banner reads: “We only hope to protect landscape of Sengakuji temple”. (Photo by Eugene Hoshiko/AP Photo)

The Museum of Feelings doesn't really have “exhibits" in the conventional sense; rather, visitors move from one themed alcove to another, five in total, each with its own distinctive aroma. The “Optimistic Room," bathed in vivid pink and purple light, is little more than a lightshow, with patrons using small reflective panels to bounce light around the room. Here: People interact in the “optimistic” room at the Museum of Feelings, a pop-up installation in New York, December 15, 2015. (Photo by Stephanie Keith/Reuters)

A supporter of the presidential candidate for the Honduran Opposition Alliance Against the Dictatorship for the past election, Salvador Nasralla, lies on the street in front of police officers during a demonstration against the contested re-election of President Juan Orlando Hernandez, in Tegucigalpa, Honduras on January 21, 2018. (Photo by Orlando Sierra/AFP Photo)

Runner-up. “The City of London, looking towards the Royal Exchange and the Bank of England. The ever-changing London skyline provides many excellent opportunities for cityscape photography, none more exciting than the ebb and flow of traffic at night”. (Photo by Mark Caldon/The Guardian)

German shoemaker Georg Wessels (R) presents shoes to Win Zaw Oo, who according to his medical team, at 2.3 metres (7.5 ft), is Myanmar's tallest man, in Yangon March 26, 2014. (Photo by Reuters/Minzayar)

Journalists report during a media tour near the volcano on the island of La Palma in the Canaries, Spain, Wednesday, September 22, 2021. A volcano on a small Spanish island in the Atlantic Ocean erupted on Sunday, forcing the evacuation of thousands of people. Experts say the volcanic eruption and its aftermath on a Spanish island could last for up to 84 days. The Canary Island Volcanology Institute said Wednesday it based its calculation on the length of previous eruptions on the archipelago. (Photo by Emilio Morenatti/AP Photo)

“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)