The current energy system contributes to many environmental issues, including climate change, air pollution, biodiversity loss, the release of toxics into the environment and water scarcity. Energy production and consumption is responsible for 72% of annual human-caused greenhouse gas emissions as of 2014. Generation of electricity and heat contributes 31% of human-caused greenhouse gas emissions, use of energy in transport contributes 15%, and use of energy in manufacturing and construction contributes 12%. An additional 5% is released through processes associated with fossil fuel production, and 8% through various other forms of fuel combustion.