I am going to opt as i have done my masters in this subject. Albeit Environmental science by Dr. Farooq Ahmad is a good book but i will suggest you guys not to rely on book rather read and collect material from internet, newspapers etc. The topics like history, sustainable development issues, global initiatives, environmental pollution, climate change, environmental governance, assessment and management may be present in any book but will not be well covered and updated. So in my opinion Internet is the best option.