Useful Sites Volterra Consulting Ltd - Parent company of The Environment Business Environmental Finance The Carbon Trading Global Exchange International Energy Agency Greenhouse & Energy Trading Simulation phase 2 Emissions Trading Education Initiative Emissions Marketing Association International Petroleum Industry Environmental Conservation Association Environmental Defense United Nations Framework Convention on Climate Change Centre for Clean Air Policy Intergovernmental Panel on Climate Change DEFRA Environment Page World Energy Council International Emissions Trading Authority Natsource - Traders of emissions units