| Agriculture | 35 | 34 |
| Air quality | 16 | 6 |
| Aquaculture | 17 | 8 |
| Atmospheric science | 16 | 13 |
| Biodegradable | 23 | 29 |
| Biodiversity | 22 | 18 |
| Biofuels | 13 | 3 |
| Biomass | 17 | 12 |
| Carbon trading | 10 | 4 |
| Clean energy | 21 | 19 |
| Climate adaption | 13 | 13 |
| Climate change | 12 | 14 |
| Climate justice | 12 | 12 |
| Climatology | 18 | 12 |
| Coastal research | 21 | 17 |
| Conservation | 25 | 19 |
| Disaster risk management | 12 | 8 |
| Earth science | 36 | 39 |
| Eco-hacking | 17 | 27 |
| Eco-tourism | 26 | 25 |
| Ecology | 15 | 27 |
| Energy | 24 | 25 |
| Energy efficiency | 25 | 24 |
| Energy engineering | 30 | 29 |
| Energy trading | 29 | 26 |
| Environment | 27 | 30 |
| Environmental health and safety (EHS) | 26 | 15 |
| Environmental impact | 29 | 22 |
| Environmental protection | 25 | 20 |
| Environmental remediation | 27 | 25 |
| Environmental science | 22 | 26 |
| Fisheries | 12 | 3 |
| Forestry | 22 | 7 |
| Geothermal | 9 | 2 |
| Glacier research | 14 | 7 |
| Green advocacy | 5 | 4 |
| Green communities | 12 | 8 |
| Green construction | 17 | 20 |
| Green economy | 23 | 27 |
| Green education | 24 | 9 |
| Green legal issues | 14 | 12 |
| Green policy | 7 | 13 |
| Green recreation | 13 | 16 |
| Green research | 21 | 17 |
| Green socioeconomic development | 17 | 18 |
| Green solutions | 32 | 10 |
| Health and safety | 20 | 22 |
| Hydrology | 9 | 8 |
| Infrastructure | 25 | 4 |
| Land use planning | 23 | 28 |
| Landscape architecture | 12 | 22 |
| Leadership in energy and environmental design (LEED) | 21 | 21 |
| Natural pesticides | 16 | 22 |
| Naturalist | 17 | 22 |
| Pollution prevention | 17 | 18 |
| Public health | 23 | 27 |
| Recycling | 10 | 22 |
| Regulation enforcement | 15 | 17 |
| Renewable | 15 | 5 |
| Renewable energy | 19 | 29 |
| Solar | 15 | 6 |
| Solid waste management, treatment, and reduction | 13 | 14 |
| Sustainability | 20 | 13 |
| Sustainable communities | 18 | 16 |
| Transportation | 25 | 15 |
| Urban and regional planning | 11 | 17 |
| Waste reduction | 18 | 10 |
| Wastewater management, treatment, and reduction | 27 | 4 |
| Water resources | 25 | 33 |
| Weatherization | 13 | 3 |
| Wildlife | 15 | 8 |
| Wind | 9 | 3 |
