Related by context. Frequent words. (Click for all words.) 66 greenhouse gases 64 fossil fuels 60 greenhouse gasses 60 heat trapping gases 57 carbon dioxide 57 fossil fuel 56 carbon dioxide emissions 55 greenhouse emissions 54 Carbon dioxide 54 greenhouse gas emissions 53 GHGs 53 carbon emissions 52 global warming 51 anthropogenic 51 greenhouse gas 50 emissions 50 carbon dioxide CO2 49 CO2 emissions 49 gases 49 nitrogen oxides 49 CO2 48 methane 48 regulate carbon dioxide 48 atmospheric carbon dioxide 48 GHG emissions 47 climate change 47 air pollution 46 pollutants 45 Emissions 45 reduce carbon emissions 45 emission reductions 45 global warming gases 45 sulfur dioxide 45 greenhouse gas GHG emissions 45 pollution 44 mercury pollution 44 pollutant 44 polluters 44 nitrogen oxide 44 Global warming 44 CFCs 44 renewables 44 polluting 44 combustion 44 biofuels 43 environmentally damaging 43 reducing carbon emissions 43 mercury emissions 43 carbon dioxide CO2 emissions 43 sulfur dioxide emissions 43 polluting industries 43 Climate Change IPCC 43 aerosols 42 acid rain 42 coal fired 42 water vapor 42 gasses 42 greenhouse gas emission 42 coal 42 carbon sinks 42 ozone pollution 42 Global Warming 41 renewable 41 deforestation 41 particulate matter 41 carbon emission 41 polluter 41 reducing CO2 emissions 41 reduce greenhouse gas 41 polar regions 41 liquid fuels 41 particulates 40 CO2 emission 40 tailpipe emissions 40 bio fuels 40 emission reduction 40 regulate greenhouse gases 40 ozone layer 40 combating global warming 40 nitrogen oxide emissions 40 renewable energies 40 biomass 40 carbon 39 methylmercury 39 ultraviolet radiation 39 alternative fuels 39 cleaner burning 39 cleaner fuels 39 alternative energies 39 volcanic eruptions 39 ozone 39 syngas 39 hydrogen 39 internal combustion 39 renewable energy 38 combustion engine 38 melting glaciers 38 acidification 38 hydroelectricity 38 soot 38 GHG