Talks at the U.N. climate summit in Warsaw, Poland, are in their final day. A coalition of environmental groups staged a walkout on Thursday in protest of the failure to reach a binding deal limiting emissions. A new study, meanwhile, shows just 90 corporations have been responsible for nearly two-thirds of all greenhouse gas emissions since the Industrial Revolution began in 1854. According to the Climate Accountability Institute, half of all emissions have been produced in the past 25 years. The top corporate polluters are Chevron, ExxonMobil, Saudi Aramco, BP and Gazprom.