Santa, a dog abandoned two days before Christmas, is looked after by Charlene Gunner at Battersea Dogs and Cats Home on December 27, 2012 in London, England. The home was founded 150 years ago and has rescued, reunited and rehomed over three million dogs and cats. The average stay for a dog is just 28 days although some stay much longer. Around 550 dogs and 200 cats are provided refuge by Battersea at any given time. (Photo by Peter Macdiarmid)

This image provided by NASA shows parts of Europe and Africa very easily recognizable in this night time image shot by one of the Expedition 25 crew members aboard the International Space Station flying 220 miles above Earth on Thursday October 28, 2010. The view “looks” northward over Sicily and the “boot” of Italy, with the Mediterranean Sea representing most of the visible water in the view and the Adriatic Sea to the right of center. Tunisia is partially visible at left. Part of a docked Russian spacecraft and other components of the ISS are in the foreground. (Photo by AP Photo/NASA)

Lightning from a tornadic thunderstorm passing over Clearwater, Kansas strikes at an open field May 19, 2013. A massive storm front swept north through the central United States on Sunday, hammering the region with fist-sized hail, blinding rain and tornadoes, including a half-mile wide twister that struck near Oklahoma City. News reports said at least one person had died. (Photo by Gene Blevins/Reuters)

A woman waits to hear about her sister, a teacher, following a shooting at the Sandy Hook Elementary School in Newtown, Connecticut. A man killed his mother at their home and then opened fire inside the elementary school where she taught, massacring 26 people, including 20 children, as youngsters cowered in fear to the sound of gunshots reverberating through the building and screams echoing over the intercom. (Photo by Jessica Hill/Associated Press)

A Waura Indian woman watches the activities of this year's “quarup”, a ritual held over several days to honour in death a person of great importance to them, in Xingu National Park, Mato Grosso State, August 24, 2013. This year the Waura tribe is honouring their late cacique (chief) Atamai, who died in 2012 and helped created the Xingu Park, and his important contribution in facilitating communication between white Brazilians and Indians. (Photo by Ueslei Marcelino/Reuters)

A Pakistani feeds his goat wearing the words “Eid Mubarak” or “Eid Greeting”, to be slaughtered on the Muslim holiday of Eid al-Adha, or “Feast of Sacrifice”, in Islamabad, Pakistan on Tuesday, October 15, 2013. Muslims all over the world are celebrating Eid al-Adha by sacrificing sheep, goats, cows and camels, to commemorate the Prophet Abraham's readiness to sacrifice his son, Ismail, on God's command. (Photo by Anjum Naveed/AP Photo)

A child parades on a float during the Bun Festival on May 25, 2015 in Hong Kong, Hong Kong. One of Hong Kong's most colourful cultural celebration event, Cheung Chau Bun Festival, will be staged on 25 May 2015 (Monday) till 26 May 2015 midnight (Tuesday). This festival has over 100 years of history. Every year, thousands of people descend upon the tiny island for The Piu Sik (Floating Colours) Parade, Lucky Bun (Ping On Bun) and The Bun Scrambling Competition, the ancient custom during the festival. (Photo by Lam Yik Fei/Getty Images)

“Environmental Migrants: The Last Illusion” by photographer Alessandro Grassani, documents the life of people in Kenya, Mongolia and Bangladesh who migrate to escape environmental stresses to the city of their own countries in hopes for a better life. Here: Asia, Mongolia, March 27, 2011. A view of Ulaan Baator over the shoulder of a slumbering drunk. Alcoholism is a huge problem in the city, home to almost half of Mongolia's people. The capital's population has doubled in the past two years. High levels of unemployment and poverty await herders who abandon rural areas and arrive in the city, illiterate and untrained in any skills necessary for urban jobs. (Photo by Alessandro Grassani)