By City A.M. Comment Desk In the UK and other countries, there are mandatory carbon markets covering specific industry sectors and gases. One carbon credit can offset one tonne of carbon. But the government permits the buying and selling of carbon credits so as to allow more flexibility. These credits are then traded in voluntary carbon markets (VCMs). Organisations voluntarily participate in the scheme because their shareholders, employees or customers want them to do so. This is opposed to mandatory schemes like carbon taxes or cap and trade systems. Compensate for unavoidable emissions by i…