Labourers walk near trucks loaded with logs, which are trapped on a muddy road, near an unreserved forest in the village of Igbatoro, southwest Nigeria, August 28, 2014. Wood, a form of biomass, is the sole source of energy for hundreds of millions of Africans who lack access to modern sources of power, and logging, both legal and illegal, remains a lucrative business that has contributed to the rapid shrinking of Africa's rainforests and woodlands. (Photo by Akintunde Akinleye/Reuters)

Visitors review their cell phone photos of an installation called “Plexus A1” by artist Gabriel Dawe, one of nine large-scale art installations displayed at the “Wonders” exhibit at the Renwick Art Gallery in Washington, DC, Wednesday, January 13, 2016. Built in the 1860s, the Renwick was the first American building to be designed specifically as an art museum; it recently reopened after a two year renovation. (Photo by Jim Lo Scalzo/EPA)

Aerobatic pilot Sean D. Tucker flies in the two-seat Oracle Extra airplane over downtown Chicago skyline, Wednesday, June 8, 2016. Tucker will perform before the start of of the America's Cup World Series racing on Saturday and Sunday. (Photo by Kiichiro Sato/AP Photo)

An Indian artist gives the finishing touches to a figure of the elephant-headed Hindu god Ganesha at a workshop ahead of the Ganesh Chaturthi festival in New Delhi on September 15, 2015. The idol is meant for the forthcoming festival Ganesha Chaturthi, a ten-day long event which is celebrated all over India. During the Ganpati festival, that is celebrated as the birthday of Lord Ganesha, idols of the Hindu deity are worshipped at hundreds of pandals or makeshift tents before they are immersed into water bodies. This year, the festival starts on 17 September 2015. (Photo by Sajjad Hussain/AFP Photo)

Freshmen in Zhengzhou Institute of Aeronautical Industry Management head bottles of mineral water for upright stand during military training on September 17, 2015 in Zhengzhou, Henan Province of China. More than 6,800 freshmen in the school are required to take part in the military training. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

Indian artist, Ravi Kali (32), dressed as Hindu goddess Kali, participates in a religious procession for the Hindu festival, Ganesh Chaturthi in New Delhi on September 24, 2015. (Photo by Chandan Khanna/AFP Photo)

Members of the Indian Border Security Force (BSF) demonstrate their skills on motor-bikes during the BSF Golden Jubilee Day celebration in New Delhi on December 1, 2015. (Photo by Money Sharma/AFP Photo)

A Malaysian woman walks past an advertisement outside a jewellery store at a shopping mall in Kuala Lumpur on August 25, 2015. Prices of crude oil and most other commodities rebounded in Asia on August 25 but stayed under pressure following a global sell-off sparked by the faltering economy in China, the world's top user of industrial metals and energy. Gold prices remained steady, boosted by prospects of increased demand due to its status as a safe haven in times of turmoil. (Photo by Manan Vatsyayana/AFP Photo)