You could create a lawn that doesn't need mowing.

iStockphotos

Planting trees and shrubs

They shade buildings and absorb CO₂ and other greenhouse gases from the air.

Rethinking yard work

Leaf and snow blowers use gas or electricity, but raking and shoveling emit no greenhouse gases.

Replacing gas-powered lawn mowers

Replacing grass with other ground cover

create a "lawn" that doesn't need mowing.

Cutting back on recreational vehicles

Each gallon of gas burned emits 9 kilograms (20 pounds) of CO₂; each gallon of diesel emits 10 kilograms (22 pounds).