Before industrialization took place, the carbon emitted was naturally removed from the atmosphere. Since its beginning in 1700's, the carbon cycle gas become off balance resulting in a hole in the Ozone layer. In 2006, only 13% of total carbon emissions was naturally sequestered.
And this is where carbon offsets come in. The offset can be created by supporting renewable energy sources like solar, wind or we can also fund activities like planting a tree. One thing we have to remember is carbon offset is not an immediate process.
Other things we can do to reduce the emissions individually are eating locally grown foods and utilizing public transportation. And hence conserve energy.