Environmental aspects 374 Studies 91 Analysis 63 Climatic changes 63 Climate change 62 Energy policy 48 Economic aspects 33 Research 31 Usage 31 Environmental policy 29 Methods 28 Laws, regulations and rules 26 Observations 25 Energy 24 Global temperature changes 24 Energy efficiency 22 Greenhouse gases 20 Social aspects 20 Emissions (Pollution) 19 Emissions control 19 Planning 18 Control 17 Energy consumption 17 Political aspects 17 Environmental impact 16 Global warming 16 Economic models 15 Ecosystems 15 Emissions credit trading 15 Air quality management 14