The article explores how companies are responding to climate change by reporting their greenhouse gas emissions, specifically carbon disclosure. It discusses the evolution of carbon trading and disclosure, using theories of global governance and institutional theory. The Carbon Disclosure Project (CDP) has been successful in getting firms to disclose information about their climate activities, but the information provided may not be very useful for investors, NGOs, or policymakers. While progress has been made in technical terms, there is still work to be done in terms of cognitive and value dimensions in carbon disclosure.