A pro-Russian rebel guards a captured former Ukrainian Army checkpoint outside Vuhlehirsk, Donetsk region, eastern Ukraine, Thursday, February 5, 2015. The rebels have closed in around the town in a strategy they triumphantly refer to as the Debaltseve cauldron. Separatists recently burst through government lines in the rural settlement of Vuhlehirsk. (Photo by Vadim Braydov/AP Photo)

A “nail house”, the last building in the area, sits in the middle of a road under construction in Nanning, Guangxi Zhuang Autonomous Region April 10, 2015. According to local media, the owner of the house didn't reach an agreement with the local authority about compensation of the demolition. (Photo by Reuters/Stringer)

Francisco da Silva Vale, 61, cools off fish with ice produced on solar-powered ice machines at Vila Nova do Amana community in the Sustainable Development Reserve, in Amazonas state, Brazil, September 23, 2015. Three solar-powered machines, are producing about ninety kilos of ice per day, in a region with poor access to electric energy, which used to be produced only with diesel oil, in the Amazon rain forest. (Photo by Bruno Kelly/Reuters)

Men look on from the banks of Rio Doce (Doce River), which was flooded with mud after a dam owned by Vale SA and BHP Billiton Ltd burst, as the river joins the sea on the coast of Espirito Santo in Regencia Village, Brazil, November 22, 2015. (Photo by Ricardo Moraes/Reuters)

Egmont National Park in New Zealand with Mt. Taranaki at its center is seen in a Landsat 8 satellite image taken July 3, 2014 and released by NASA November 14, 2014. The image is from the book “Sanctuary: Exploring the World's Protected Areas from Space”, published by the Institute for Global Environmental Strategies with support from NASA, which was released this week. (Photo by Reuters/NASA/USGS)

Super-cell thunderstorms, whirling tornados and lightning bolts illuminating the sky – these photos capture the terrifying brilliance of American storms. (Photo by Brandon Goforth/Solent News & Photo Agency)

A general view of dried-up rivers in the Pilbara region of Western Australia December 2, 2013. Western Australia's Pilbara region, which is the size of Spain, has the world's largest known deposits of iron ore and supplies nearly 45 percent of global trade in the mineral. (Photo by David Gray/Reuters)