Human negligence and greed are responsible for the environmental degradation.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/world-environment-day-little-done-much-required
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/statesman-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environmental-health
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environmentalists
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cop-21-paris
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/organic-farming
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/renewable-energy
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environmental-security
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment