In fact, I'd go so far as to suggest that the total elimination of lawns could actually lead to environmental disaster. A mere 625 square feet of lawn provides enough oxygen for one person for an entire day, and a large lawn could help more than 100 people breathe easier. On a block of eight average homes, front lawns have the same cooling effect as 70 tons of air conditioning. Turf grasses absorb gaseous pollutants such as carbon dioxide and sulfur dioxide, and trap an estimated 12 tons of dirt and dust that would be released each year into the atmosphere. A buffer zone of grass around buildings helps retard the spread of fires.
Lawns also prevent soil erosion, reduce runoff and filters contaminants from rainwater.
Lawns help keep our lakes and streams clean by filtering and purifying rainwater, and they do the job better than plants such as groundcovers or wildflowers. But expending a lot of resources to maintain such a good thing is counterproductive. Use a mulching mower, which saves time and also provides a significant amount of food for the lawn. Use compost as a means of feeding the lawn naturally. Don't use herbicides and other lawn chemicals.