Voluntary carbon offsets have been traded in relatively small volumes and on a demonstration basis since the late 1980s. Some organizations, such as the Climate Trust in Oregon, have many years of experience in purchasing and retiring offsets on behalf of clients or customers (the Climate Trust was established in 1997 to assist new power plants in Oregon to meet a state regulatory requirement for net CO2 emissions). As the data above indicate, however, there has been a dramatic increase in the last two years in the number of voluntary offset transactions, with an accompanying expansion in the number of.
