carbon offset

noun

: an action or activity (such as the planting of trees or carbon sequestration) that compensates for the emission of carbon dioxide or other greenhouse gases to the atmosphere

A carbon offset occurs when an individual company or organization directly or indirectly (by funding projects in other locations) removes greenhouse gases from the atmosphere or prevents a certain quantity of greenhouse gases from being released.—

Tyson Miller, Publishers Weekly, 10 Mar. 2008

also : a quantifiable amount of such an activity that may be bought, sold, or traded especially as part of a system to reduce pollutants in the atmosphere

Purchase carbon offsets. For every pound of carbon dioxide your home releases, you can fund an environment-friendly endeavor that reduces the amount of greenhouse gases released into the air. —

Suze Orman, O: The Oprah Magazine, Fall 2007

When you purchase carbon offsets, you are funding a project that reduces greenhouse-gas emissions elsewhere by, for example, increasing energy efficiency, developing renewable energy, restoring forests, or sequestering carbon in soil. —

Al Gore, An Inconvenient Truth, 2006