Carbon markets can be either voluntary or mandatory. The main difference between the two is that the voluntary market is unregulated. Recognised international standards, such as Gold Standard exist to monitor and verify the quality and validity of the carbon credits that are traded in the voluntary market.
Compliance schemes are currently aimed at the most “energy intensive” emitters (at a company level). These include power generators, oil refineries, iron and steel production and processing companies, those who produce commodities such as cement, glass and ceramics and the paper and pulp industry.
The voluntary market serves the purpose of businesses (typically blue-chip corporations), government departments, NGOs and single individuals wanting to be accountable for their carbon footprint and help drive the transition to a low-carbon future.