| World Wetlands Day | 02-02: February 2 |
| International Polar Bear Day | 02-27: February 27 |
| World Wildlife Day | 03-03: March 3 |
| Solar Appreciation Day | Second Friday of March |
| International Day of Action for Rivers | 03-14: March 14 |
| World Consumer Rights Day | 03-15: March 15 |
| World Sparrow Day | 03-20: March 20 |
| International Day of Forests | 03-21: March 21 |
| World Planting Day | 03-21: March 21 |
| World Wood Day | 03-21: March 21 |
| World Water Day | 03-22: March 22 |
| Earth Day | 04-22: April 22 |
| World Fish Migration Day | April 21, 2018 |
| Day of Remembrance for all Victims of Chemical Warfare | 04-29: April 29 |
| Green Up Day | 05: first Saturday of May in Vermont |
| Greenery Day | 05-04: May 4 in Japan (previously April 29) |
| World Migratory Bird Day | second Saturday in May |
| International Migratory Bird Day | second Saturday in May (in the U.S. and Canada) and second Saturday in October (in Mexico, Central and South America, and the Caribbean) |
| International Recycling Day | May 17th, 2017 |
| Endangered Species Day | 05-19: May 19 |
| International Day for Biological Diversity (World Biodiversity Day) | 05-22: May 22 |
| World Turtle Day | 05-23: May 23 |
| European day of parks (Europarc) | 05-24: May 24 |
| Bike-to-Work Day | 05: third Friday in May |
| World Environment Day | 06-05: June 5 |
| World Oceans Day | 06-08: June 8 |
| Coral Triangle Day | 06-09: June 9 |
| Global Wind Day | 06-15: June 15 |
| World Sea Turtle Day | 06-16: June 16 |
| World Day to Combat Desertification and Drought | 06-17: June 17 |
| World Giraffe Day | 06-21: June 21 |
| World Population Day | 07-11: July 11 |
| International Tiger Day | 07-29: July 29 |
| World Lion Day | 08-10: August 10 |
| World Elephant Day | 08-12: August 12 |
| World Orangutan Day | 08-19: August 19 |
| National Honey Bee Day | 08-22: August 22 |
| Amazon Day | 09-05: September 5 |
| International Day for the Preservation of the Ozone Layer | 09-16: September 16 |
| World Cleanup Day | 09-15: September 15, 2018 |
| World Water Monitoring Day | 09-18: September 18 |
| Zero Emissions Day | 09-21: September 21 |
| Car Free Day | 09-22: September 22 |
| World Rhino Day | 09-22: September 22 |
| Ecological Debt Day (Earth Overshoot Day) | 09-23: September 23 in 2008, but receding |
| World Environmental Health Day | 09-26: September 26 since 2011 (IFEH) |
| World Rivers Day | 09: last Sunday in September |
| World Habitat Day | 10: first Monday in October |
| World Animal Day | 10-04: October 4 |
| Energy Efficiency Day | 10-05: October 5 since 2016 |
| International Day for Natural Disaster Reduction | 10: second Wednesday in October , October 13. |
| Sustainability Day | 10: fourth Wednesday of October |
| International Snow Leopard Day | October 23 |
| International Day of Climate Action | 10-24: October 24 |
| World Vegan Day | 11-01: November 1 |
| International Day for Preventing the Exploitation of the Environment in War and Armed Conflict | 11-06: November 6 |
| America Recycles Day | 11-15: November 15 |
| World Soil Day | 12-05: December 5 |
| International Mountain Day | 12-11: December 11 |
| Ozone Action Day | at certain times during the summer months |
| eDay | variable date |