Burning coal releases enormous amounts of carbon dioxide per unit of energy. The increasing emission of carbon dioxide since the Industrial Revolution is considered as a key factor of global warming. Lignite (brown coal) power stations emit 850-1200 g CO2 per kWh which is more carbon dioxide than (black) coal power plants do with 750-1100 g CO2 per kWh.

We collected some interesting links on this item for you:
www.pce.parliament.nz/media/pdfs/PCE-Lignite.pdf Lignite and climate change: The high cost of low grade coal
Health impacts of lignite-fired power plants