Members of the Coney Island Polar Bear Club warm up before swimming at the beach at Coney Island in New York, December 15, 2013. (Photo by Eric Thayer/Reuters)

Clearing skies await a tripod-toting photographer looking for a spot to capture the early-morning light at Portland Head Light, Thursday, January 17, 2013, in Cape Elizabeth, Maine. (Photo by Robert F. Bukaty/AP Photo)

Labourers who work nearby nap on a road as cars drive past in Chongqing Municipality, July 23, 2013. (Photo by Reuters/Stringer)

Four men dressed as zombies participate in a Zombie Walk procession in the streets of Paris October 12, 2013. (Photo by Benoit Tessier/Reuters)

A young Free Syrian Army fighter holds a rifle in Haresta neighbourhood of Damascus January 16, 2013. (Photo by Goran Tomasevic/Reuters)

An enthusiast dressed as a zombie takes part in the annual Zombie Walk festival in Prague June 1, 2013. (Photo by David W. Cerny/Reuters)

Replica of an old traditional Icelandic house from the 1800 with eruption of Iceland's Eyjafjallajökull volcano, 2013. (Photo by Ingólfur Bjargmundsson/Getty Images)

A boy poses with a butterfly on his face during a photocall to promote the “Sensational Butterflies” exhibition at the Natural History Museum in central London, on March 25, 2013. With around 400 live tropical butterflies and moths living in the temporary facility, visitors will get the chance to see them flying freely as well as looking for emerging butterflies at the hatchery window. Running from March 29 to September 15, 2013, the exhibition is housed in a structure in the museum grounds. (Photo by Leon Neal/AFP Photo)