Planting trees is an efficient way of locking away carbon dioxide safely.
Using a CO2 calculators ( http://www.co2balance.com/pages.php?pageid=3 ), you can estimate the amount of CO2 that your family is responsible for producing each year and then calculate how many trees you need to plant to offset or balance your carbon dioxide production.
As most people don’t have enough space in their gardens to plant trees, there are several organisations that will plant trees on your behalf: