Chinese Artist Ai Weiwei holds some seeds from his Unilever Installation “Sunflower Seeds” at The Tate Modern on October 11, 2010 in London, England. The sculptural installation comprises 100 million handmade porcelain replica sunflower seeds. (Photo by Peter Macdiarmid/Getty Images)

People at a Czech Stop look at a cloud of smoke rising from the explosion in West, Texas, April 17, 2013. (Photo by Andy Bartee via Dallas Morning News/MCT)

An ice covered entrance door to the international gene bank Svalbard Global Seed Vault (SGSV) near Longyearbyen on Spitsbergen, Norway, October 20, 2015. Two consignments of crop seeds will be deposited next year in a “doomsday vault” built in an Arctic mountainside to safeguard global supplies. The vault, which opened on the Svalbard archipelago in 2008, is designed to protect crop seeds, such as beans, rice and wheat against the worst cataclysms of nuclear war or disease. (Photo by Anna Filipova/Reuters)

A picture made available on 08 July 2015 showsa lightning strikes during a heavy storm over Poznan in the night of 07 July 2015. Severe storms passed last night over Poland causing lots of damages to buildings, trees, electricity and railway tractions. (Photo by Lukasz Ogrodowczyk/EPA)

An East German civilian (L) shows an East German customs officer the contents of his Trabant (auto) at checkpoint Potsdamer Platz in East Berlin in this November 24, 1989 file picture, as East Germany enforcing stringent customs controls to avoid smuggling. (Photo by Reuters)

Lightning streaks across the sky as lava flows from a volcano in Eyjafjallajokul April 17, 2010. (Photo by Lucas Jackson/Reuters)

Lightning strikes during a storm over the Ionian Sea in Calabria, Italy on June 27, 2016. (Photo by Alfonso Di Vincenzo/Pacific Press/Rex Features)

A horse-drawn cart passing through a section cut out of the base of a giant sequoia tree in the Mariposa groves of Yosemite Park, California. (Photo by Carleton E Watkins/Getty Images). 1870