Greenpeace activists climb the 300 meter high smokestack of the Prunerov II brown coal-fired power station to highlight that Prunerov II is the largest source of carbon dioxide emissions in the Czech Republic. Coal is the most polluting of all fossil fuels and the largest single source of CO2 in the world. Currently, one-third of all carbon dioxide emissions come from burning coal. Quitting the use of coal is essential to a meaningful deal to save the climate.