The Delhi Metro is the first rail network in the world to have two projects registered with the UN Framework Convention on Climate Change.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/delhi-metro%E2%80%99s-steps-climate-change-bring-earnings
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/asian-age-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi-metro-rail-corporation-dmrc
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/unfccc
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/carbon-dioxide
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/atmosphere
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicles
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/electricity
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi