Noun
carbon offset (plural carbon offsets)
A reduction in carbon dioxide emission by a third party purchased by a heavy carbon dioxide producer as part of carbon emissions trading.
Carbon offset programs are planting millions of fast-growing trees per year to reforest tropical lands, for as little as $0.10 per tree; over their typical 40-year lifetime, one million of these trees will fix 1 to 2 MegaTonnes of carbon dioxide. Source: Internet