A child looks at a polar bear swimming under a water in its enclosure on a hot summer day at Prague Zoo, Czech Republic, July 30, 2015. (Photo by David W. Cerny/Reuters)

A sofa floats in the polluted waters of Jacarepagua Lagoon, during a press tour in Rio de Janeiro, March 9, 2015. A press tour was organised by biologist Mario Moscatelli, to call attention to pollution on the waters of the lagoons which surround the Rio 2016 Olympic Park. (Photo by Ricardo Moraes/Reuters)

An aerial view of open pits of CODELCO's Andina (L) and Anglo American's Los Bronces copper mines with Olivares glaciers in the background (top L) at Los Andes Mountain range, near Santiago city, November 17, 2014. The rock glaciers of the Chilean central zone, a huge source of water for the basins of the capital, are said to be threatened by the environmental impacts of hydroelectric and mining projects, according to environmental activists Greenpeace. (Photo by Ivan Alvarado/Reuters)

“APOPO’s Training Center, situated on Sokoine Univeristy of Agriculture (SUA) in Tanzania, was established in 2000 to accommodate training and testing of mine detection rats in near-to-real conditions”. – APOPO

Photo: MDR (Mine Detection Rat) learn to look for mines. (Photo by APOPO's HeroRATs)

A member of the United States Naval Academy freshman class wears body armor, helmet and carries a rifle through a mud-filled ditch as part of the “Wet and Sandy” challenge during the rigorous Sea Trials May 17, 2011 in Annapolis, MD. Under strict safety supervision, about 900 freshmen, or “Plebes”, faced 14 hours of 32 rigorous physical and mental challenges during the trials, a daylong, action-oriented event modeled after the Marine Corps 54-hour Crucible and the Navy's Battle Stations. (Photo by Chip Somodevilla/Getty Images)

Mike “The Bedfordshire Bull Botteley” (left) takes on Chris “The General” Levy during a Chessboxing bout at the Scala nightclub on March 10, 2012 in London, England. A new hybrid sport combining chess and boxing in alternate 3 minute rounds, the winner is the one who knocks out or checkmates their opponent first. (Photo by Matthew Lloyd/Getty Images)

Purev and Buyantogtokh enjoy the warmth of the fire in the snow in Altai Mountains, Mongolia, September 2016. Navigate the snowy wilds of Mongolia with this nomadic reindeer herding family. Photographer Joel Santos dived 1000km into the depths of Northern Mongolia to visit the Ganbaa family near Khovsgol Lake. (Photo by Joel Santos/Barcroft Images)