Oxygen makes the world a better place! So plant some bushes and trees, or dig a pond and let there be algae. (Yipee!) I suppose its best to do this in a poor ecosystem like a lawn or a desert. July 1 2012
Stop mowing your lawn, or persuade someone to stop mowing theirs, then plant with fruit trees/bushes (lawns are poor ecosystems, lawnmowing creates continous pollution and energy use) April 26 2012