Related by context. Frequent words. (Click for all words.) 73 greenhouse gases 72 greenhouse gas emissions 69 greenhouse emissions 69 greenhouse gas 67 carbon dioxide emissions 67 heat trapping gases 67 emissions 64 carbon emissions 60 emission reductions 59 carbon dioxide 59 carbon emission 58 GHG emissions 58 CO2 emissions 58 emission reduction 57 mercury emissions 57 emission 56 reduce carbon emissions 54 Emissions 54 reducing carbon emissions 53 CO2 53 GHG 52 nitrogen oxides 51 air pollution 50 pollution 50 sulfur dioxide 49 polluters 49 Kyoto Protocol 48 pollutants 48 global warming 46 emitters 46 Kyoto 45 burning fossil fuels 44 reduce greenhouse gas 44 carbon 44 climate change 44 fossil fuels 44 pollutant 44 acid rain 42 coal fired 42 polluter 42 reducing greenhouse gas 41 Kyoto protocol 41 soot 41 renewable fuels 41 renewables 40 Environmental Protection Agency 40 fossil fuel 40 particulate matter 40 renewable energy 40 EPA 40 Copenhagen Accord 40 carbon credits 39 smog 39 cleaner burning 39 gases 39 mercury 39 polluting 39 carbon footprint 39 ozone 39 carbon offsets 38 alternative fuels 38 Environmentalists 38 biofuels 38 nuclear arsenals 38 methane 38 Clean Air 37 zero emission 37 renewable 37 carbon footprints 37 phosphorus 37 environmentalists 36 legally binding 36 renewable energies 36 Strategic Arms Reduction Treaty 36 ethanol 36 electric utilities 36 toxic chemicals 36 pollute 36 Climate Change IPCC 35 deforestation 35 biofuel 35 Climate Change 35 carbon capture 35 Renewable energy 35 Pachauri 35 Natural Resources Defense 35 farm subsidies 35 emitter 35 oceans 35 climate 34 trans fats 34 Sierra Club 34 secondhand smoke 34 volatile organic compounds 34 phosphorous 34 tropical forests 34 mpg 34 gas guzzling 34 coal 34 carbon neutral 33 Global warming