Holy days provide us with a beyond-the-everyday opportunity to reflect in celebration or in solemnity upon the season. Earth Day is the first holy day which transcends all faiths and traditions, and so you may wish to anchor your environmental calendar in the spring.
Advent and Ecology Liturgy
https://www.arcworld.org/faiths.asp?pageID=78
Canfei Nesharim: Holy Days
https://canfeinesharim.org/learning/make_difference.php
Celebrating and Caring for God’s Creation
https://www.pcusa.org/peacemaking/worship/earthday09.pdf
Coalition on the Environment and Jewish Life: Celebrate
https://www.coejl.org/celebrate/
Earth Day Liturgy from the NCC
https://www.beliefnet.com/Faiths/Christianity/2001/04/Earth-Day-Liturgy-From-The-National-Council-Of-Churches.aspx
Earth Ministry: The Liturgical Year
https://www.earthministry.org/resources/worship-aids/liturgical-year
Season of Creation
https://www.earthministry.org/resources/worship-aids/liturgical-year
The Shalom Center: Celebrations
https://www.shalomctr.org/taxonomy_menu/1/126
Sukkot: Season of Gathering and Giving
https://urj.org/_kd/Items/actions.cfm?action=Show&item_id=4446&destination=ShowItem