| Clue | Source | Date |
|---|---|---|
| They leave carbon footprints | New York Times | 02 Sep 2017 |
| They leave carbon footprints | ||
| Carbon dioxide and methane | Newsday | 23 Nov 2016 |
| Methane and ozone | Newsday | 27 Aug 2015 |
| Methane and ozone | ||
| "An Inconvenient Truth" topic | ||
| Big topic in "An Inconvenient Truth" | ||
| "An Inconvenient Truth" topic | ||
| Atmospheric worries | ||
| "Hot" political topic | ||
| Global-warming issues | ||
| "An Inconvenient Truth" topic | ||
| Carbon dioxide and methane | ||
| CO2 and methane, to a ecoscientist | ||
| Cause of global warming |