Host Country: The country where an emissions reduction project is physically located.

Hot Air: Reductions of greenhouse gases that have occurred due to economic collapse or declined production for reasons not directly related to intentional efforts to curb emissions.

Hydrofluorocarbons (HFCs): developed to replace Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) for use primarily in refrigeration and air conditioning equipment. These gases also are inadvertently emitted during some manufacturing processes. HFCs are a potent greenhouse gas with a GWP of between 150 - 11,700 tCO2e.