"Keeping products cold throughout the mobile portion of the cold chain -- largely trucks, trains and ships -- accounts for 7 percent of global HFC consumption [hydrofluorocarbons]. Overall these HFCs contribute 4 percent of the total global warming impact of moving all freight, refrigerated or not. For each move that is refrigerated, HFCs contribute a significant portion to the climate footprint. Carrier, a United Technologies Company, has launched a new refrigeration unit that runs on carbon dioxide. The unit is for marine container applications and can cut the climate impact of the refrigeration unit by 35 percent." (Quoted from article)