Subject
Air Pollution
6
Climatic changes
Environmental sciences
6
Global warming
6
Natural resources
Pollution
6
Water use
5
Land use
3
Water-supply
3
Earth sciences
2
Geography
2
Landforms
2
Biotic communities
1
Botany
1
Business
1
Business ethics
1
Ecological regions
1
Ecological zones
1
Economics
1
Life sciences
1
Physical geography
1
Plants Evolution
1
Plants Reproduction
1
Power resources
1