In this two photo combination picture, the Eiffel Tower with its usual lighting at left, and after the lighting was switched off at right, at the occasion of the Earth Hour, in Paris, France, Saturday March 28, 2015. This Saturday, 28 March 8:30 p.m. local time, individuals, businesses, cities and landmarks around the world are switching off their lights for one hour to focus attention on climate change. (Photo by Remy de la Mauviniere/AP Photo)

Military vehicles surround a wreckage of a trolleybus, in Volgograd, Russia, Monday, December 30, 2013. A bomb blast tore through a trolleybus in the city of Volgograd on Monday morning, killing at least 10 people a day after a suicide bombing that killed at least 17 at the city's main railway station. Volgograd is about 650 kilometers (400 miles) northeast of Sochi, where the Olympics are to be held. (Photo by Denis Tyrin/AP Photo)

Pro-Russian activists attack policemen guarding the burned trade union building in the southern Ukrainian city of Odessa on May 3, 2014. More than 30 people were killed in a “criminal” blaze in Ukraine's southern city of Odessa, as violence spread across the country during the bloodiest day since Kiev's Western-backed government took power. Ukraine's interior ministry said at least 31 people had died in the fire Friday, with local media reporting that pro-Russian militants were believed to have been in the burning building at the time. (Photo by Anatolii Stepanov/AFP Photo)

In this Thursday, May 8, 2014 photo, guests look down from the Tilt!, a new tourist attraction that provides guests a unique view of the downtown area from the 94th floor of the John Hancock Building, after it was unveiled in Chicago. People hold onto handrails as the glass and steel facade tilts forward 30 degrees. (Photo by Ashlee Rezin/AP Photo/Sun-Times Media)

United States Coast Guard Academy Cadets Second Class Aurimas Juodka, left, and Sheila Bertrand get in the face of “swab” Kevin Lennox as Bravo Company finishes at the barber shop and mailroom during R-Day, the reporting-in day that marks the beginning of the 7-week “Swab Summer” for the class of 2018 Monday, June 30, 2014, in New London, Conn. About 250 prospective cadets, Swabs, start the program designed to indoctrinate them to the military life of the academy and at the end will be accepted into the corps of cadets. (Photo by Sean D. Elliot/AP Photo/The Day)

Hot air balloons fly over Igualada during an early flight as part of the European Balloon Festival on July 10, 2014 in Igualada, Spain. The early morning flight of over 30 balloons was shorter than expected due to windy weather. This flight is organised as a curtain raiser for the four-day European Balloon Festival. Now is the 18th year of the most important hot air Balloon event in Spain and one of the biggest in Europe. (Photo by David Ramos/Getty Images)

This July 2014 image provided by the Bureau of Land Management shows the interior of the Natural Trap Cave in north-central Wyoming. The cave holds the remains of tens of thousands of animals, including many now-extinct species, from the late Pleistocene period tens of thousands of years ago. Scientists have resumed digging for the first time in more than 30 years. (Photo by AP Photo/Bureau of Land Management)

In a photo taken on August 30, 2014 a man brushes his dog as he waits to take part in a competition at a dog show in Seoul. Some 2000 dogs took part in the three-day show organised by the Korea Kennel Federation which was celebrating its 58th anniversary. Dog ownership in South Korea is a growing industry widely reported to have passed 10 million in 2013, with private expenditure on pet supplies increasing some 14 percent per year since 2000, according to a report by the Nonghyup Economic Research Institute. (Photo by Ed Jones/AFP Photo)