A homeless man rests on the side of a street at the old quarter of Yemen's capital Sanaa November 27, 2015. (Photo by Khaled Abdullah/Reuters)

A Taiwanese woman takes a photo of a Christmas tree decoration at a street in Taipei, Taiwan,13 December 2015. (Photo by Ritchie B. Tongo/EPA)

A man rides his loaded tricycle next to three schoolgirls in Shanghai on December 11, 2015. (Photo by Johannes Eisele/AFP Photo)

Actors perform the living Nativity biblical scenes in Postojna cave in Postojna, Slovenia, December 22, 2015. (Photo by Srdjan Zivulovic/Reuters)

In this Tuesday, December 15, 2015 photo, an Afghan man sells traditional sauces and pickles on a street in Kabul, Afghanistan. (Photo by Massoud Hossaini/AP Photo)

An incredible clear-air lightning display from storms to the east of Noonamah, just outside Darwin on April 6, 2015. (Photo by Jacci Ingham/The Guardian)

Children play in front of a brick factory on the outskirts of the northern Myanmar city of Mandalay on December 14, 2015. (Photo by Phyo Hein Kyaw/AFP Photo)

RAF Tornados fly above the Lossiemouth air base on March 18, 2011 in Lossiemouth, Scotland. UK defence forces will help to enforce a no-fly zone over Libya after the UN voted in favour of a resolution that backed 'all necessary measures', except a foreign occupation force, to protect Libyan civilians.