Londoners walking through Potters Field Park were surprised to see a “money tree” blooming with £9820 in £10 notes, the average amount a working British family has in savings, on July 24, 2014 in London, England. The tree was planted by Sunlife to encourage the nation to start saving at least £10 a month for a brighter future. (Photo by Tristan Fewings/Getty Images for SunLife)

Elvish writing is seen on “Anduril”, a prop sword belonging to Aragorn, hero of “The Lord of the Rings” movie trilogy on July 31, 2014 in London, England. The sword, belonging to actor Sir Christopher Lee and estimated at $150,000-250,000, forms part of Bonhams “There's No Place Like Hollywood” movie memorabilia auction taking place in New York on November 24, 2014. (Photo by Peter Macdiarmid/Getty Images)

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 group of surfers ride the Bore Tide at Turnagain Arm on July 15, 2014 in Anchorage, Alaska. Alaskas most famous Bore Tide, occurs in a spot on the outside of Anchorage in the lower arm of the Cook Inlet, Turnagain Arm, where wave heights can reach 6-10 feet tall, move at 10-15 mph and the water temperature stays around 40 degrees farenheit. This years Supermoon substantially increased the size of the normal wave and made it a destination for surfers. (Photo by Streeter Lecka/Getty Images)

A vendor sells fruits and nuts at the Green Bazaar in Almaty January 23, 2015. Kazakhstan is spending billions of dollars of its reserves to keep devaluation of its currency gradual and reduce inflationary risks of the sort thrown up in Russia by the rouble's slide, analysts and former central bank officials say. Kazakhstan, Central Asia's largest economy, is closely tied to Russia through trade and, like other ex-Soviet states, has been feeling the pain of the crisis which has driven the rouble down 50 percent against the dollar since the start of 2014. (Photo by Shamil Zhumatov/Reuters)

A reveler and a child street vendor pose for a photo during the Banda de Ipanema Carnival parade in Rio de Janeiro, Brazil, Saturday, January 31, 2015. Rio's over-the-top Carnival is the highlight of the year for many local residents. Hundreds of thousands of merrymakers are beginning to take to the streets in open-air “blocos” parties. (Photo by Silvia Izquierdo/AP Photo)

Devotees offer prayer by rolling on the street during the final day of the month-long Swasthani festival of Bhaktapur, near Kathmandu, February 3, 2015. During the festival, devotees recite one chapter of a Hindu tale daily from the 31-chapter sacred Swasthani Brata Katha book, that is dedicated to God Madhavnarayan and Goddess Swasthani, alongside various other gods and goddesses and the miraculous feats performed by them. The devotees also go on pilgrimages to various temples, perform religious rituals, take a holy bath in the rivers and fast for a month, especially among women who believe fasting helps in their family's well-being or in getting them a good husband. (Photo by Navesh Chitrakar/Reuters)

A view of the screen of a ZaZZZ vending machine that contains cannabis flower, hemp-oil energy drinks, and other merchandise at Seattle Caregivers, a medical marijuana dispensary, in Seattle, Washington February 3, 2015. Vending machines selling medical marijuana opened for business in Seattle on Tuesday, in what the company providing them billed as a first-in-the-state innovation that it expects to expand to other cities and states where pot is legal as medicine. (Photo by David Ryder/Reuters)