I hope nobody planted any trees. Trees are bad for the environment - or, at least not as good as one might think. At night they release CO2 when they "burn" some of the sugar they create at day, and the process of converting carbon dioxide, water and sunlight to energy is bound to release the same amount of CO2 in addition to methane when the tree dies, seeing as the carbon is bound to the organic material of the tree in order to create new tissue (leaves, wood). As long as there isn't a direct oxygen shortage, if such a thing could actually happen, planting trees for the environment isn't really all that effective. If you want to help, grow cyanobacteria in a petri dish.
Oh, and I didn't even know it was Earth Day. Not really being picked up on by the media where I live, at least.