An abandoned tank left by Boko Haram, February 20, 2016, seen on the road to Michika, Nigeria – a town formerly occupied by the insurgents. On April 14, 2014, 300 schoolgirls in the Chibok village in Nigeria were kidnapped by the terrorist group, Boko Haram. Two years later, the majority of these girls are still missing. According to the Global Terrorism Index Report 2015, Boko Haram, which operates mainly in Nigeria, has become the most deadly terrorist group in the world. (Photo by Danielle Villasana)

A firefighter carries a woman from her car after it was caught in street flooding as a powerful storm moves across Southern California on February 17, 2017 in Sun Valley, California. After years of severe drought, heavy winter rains have come to the state, and with them, the issuance of flash flood watches in Santa Barbara, Ventura and Los Angeles counties, and the evacuation of hundreds of residents from Duarte, California for fear of flash flooding from areas denuded by a wildfire last year. (Photo by David McNew/Getty Images)

Deers walk past Indonesia's honour guard as they wait for the arrival of Saudi Arabia's King Salman bin Abdul Aziz at the presidential palace in Bogor on March 1, 2017. Cheering crowds welcomed King Salman on March 1 as he began the first visit by a Saudi monarch to Indonesia for almost 50 years, seeking stronger economic ties with the world's most populous Muslim-majority country. (Photo by Adek Berry/AFP Photo)

In this Friday, January 7, 2011 photo, people carry baskets of coal scavenged illegally at an open-cast mine in the village of Bokapahari in the eastern Indian state of Jharkhand where a community of coal scavengers live and work. The world's biggest coal users – China, the United States and India – have boosted coal mining in 2017, in an abrupt departure from last year's record global decline for the heavily polluting fuel and a setback to efforts to rein in climate change emissions. (Photo by Kevin Frayer/AP Photo)

A woman carries her child as she watches Mount Sinabung volcano spewing thick volcanic ash, as seen from Karo on July 21, 2017. Sinabung roared back to life in 2010 for the first time in 400 years, after another period of inactivity it erupted once more in 2013, and has remained highly active since. (Photo by Gatha Ginting/AFP Photo)

A tourist poses next to a tiger before officials start moving tigers from Thailand's controversial Tiger Temple, a popular tourist destination which has come under fire in recent years over the welfare of its big cats in Kanchanaburi province, west of Bangkok, Thailand, May 30, 2016. Wildlife authorities raid a Buddhist temple that has more than 100 tigers, taking away three cats and vowing to confiscate scores more in response to global pressure over wildlife trafficking. (Photo by Chaiwat Subprasom/Reuters)

s*x workers, wearing decorative skull masks, march through the streets in downtown Mexico City, Friday, October 28, 2016. The women march with candles to an altar dedicated to their departed colleagues, many who died violently at the hands of their customers. This annual procession, tied to the Day of the Dead festivities, has taken place for more than 20 years. (Photo by Eduardo Verdugo/AP Photo)

In this February 26, 1962 file photo, Mercury astronaut John Glenn, and his wife, Annie, ride in the back of an open car with Vice-President Johnson during a parade in Glenn's honor in Washington. The Capitol is seen in the background. Glenn, the first American to orbit Earth who later spent 24 years representing Ohio in the Senate, died Thursday, Dec. 8, 2016, at the age of 95. (Photo by AP Photo)