Students stand on the roof of a wooden boat as haze blankets the Musi River while they travel to school in Palembang, on Indonesia's Sumatra island, September 10, 2015. Indonesia is investigating 10 firms over worsening forest fires that have created a blanket of smog over Southeast Asia, threatening them with sanctions if they are found responsible, a government minister said on Tuesday. The thick haze from Indonesia's Sumatra and Kalimantan islands has forced the repeated cancellation of flights in the area and pushed air quality to unhealthy levels in neighbouring Singapore and Malaysia. (Photo by Reuters/Beawiharta)

Students of the "Escola de Papai Noel do Brasil" (Brazil's school of Santa Claus) travel on a ferry through Guanabara bay, during their graduation ceremony in Rio de Janeiro, Brazil, November 10, 2015. The school holds 4 days' lessons in Santa-training, teaching Christmas carols, how to interact with children, and also how to wear the heavy red suit in Rio's typical 104-degree (40 degrees celsius) summer weather that is common around the holidays. (Photo by Pilar Olivares/Reuters)

Artist Heather Dewey-Hagborg's 'Stranger Visions', comprising of 3D printed faces extracted from DNA taken from discarded cigarette butts and chewing gum, is displayed at the Big Bang Data exhibition at Somerset House on December 2, 2015 in London, England. The show highlights the data explosion that's radically transforming our lives. It opens on December 3, 2015 and runs until February 28, 2016 at Somerset House. (Photo by Peter Macdiarmid/Getty Images for Somerset House)

Runners hoist another runner into the air after completing The Color Run All-Star 5K as part of the All-Star Baseball game festivities, Saturday, July 11, 2015, at Sawyer Point Park, in Cincinnati. After more than two years of planning and sprucing up, city organizers say everything's in place for a smooth, safe and fun five days of events that began Friday morning with the opening of Major League Baseball's fan festival. There will be concerts, exhibits, celebrity softball, the Home Run Derby and other activities capped by Tuesday night's game. (Photo by John Minchillo/AP Photo)

A vendor sells fruits and nuts at the Green Bazaar in Almaty January 23, 2015. Kazakhstan is spending billions of dollars of its reserves to keep devaluation of its currency gradual and reduce inflationary risks of the sort thrown up in Russia by the rouble's slide, analysts and former central bank officials say. Kazakhstan, Central Asia's largest economy, is closely tied to Russia through trade and, like other ex-Soviet states, has been feeling the pain of the crisis which has driven the rouble down 50 percent against the dollar since the start of 2014. (Photo by Shamil Zhumatov/Reuters)

In this Saturday, March 21, 2015 photo, a porter rests carrying supplies for the upcoming climbing season, near the Everest Base camp, Nepal. Nepal has cleared more than 300 mountaineers to climb Mount Everest after they had to abandon last year's efforts when an ice avalanche killed 16 guides in the mountain's deadliest disaster, an official said on March 20. The three-month climbing season for Everest, the world's tallest mountain, begins in March. (Photo by Tashi Sherpa/AP Photo)

A Somali police officer arrests a suspected rebel member of the al Qaeda-affiliated al Shabaab among beach goers in Mogadishu. Al Shabaab claimed responsibility for today's pre-dawn attack on a Kenyan university campus near the Somali border. The following gallery examines who is al Shabaab. Here: Somali police officer (R) arrests a suspected rebel member (L) of the Al Qaeda-affiliated al Shabaab among beach goers at the Lido beach north of Somalia's capital Mogadishu March 23, 2012. (Photo by Feisal Omar/Reuters)

An aerial view shows a sinkhole 3.5 km (2 miles) to the east of Solikamsk-2 mine in Perm region, November 20, 2014. Shares in Russia's Uralkali, the world's top potash producer, fell sharply for a second day on Wednesday after a mine accident that could reduce global supplies and push up prices of the crop nutrient worldwide. Uralkali shares have fallen 28 percent since Tuesday when it suspended work at its Solikamsk-2 mine, which accounts for a fifth of the company's output and 3.5 percent of global capacity, following an inflow of water. A sinkhole, stretching 30 by 40 metres (yards), found at an abandoned mine 3.5 km (2 miles) to the east, increased concern about the future of the mine because an inflow of water and the resulting sinkhole in 2006 forced another Uralkali operation to shut permanently. (Photo by Reuters/Press service of Uralkali company)