This study, conducted in PricewaterhouseCoopers (PwC), was conducted in accordance with the environmental management standards ISO 14040 and ISO 14044 and showed that, regarding the emission of greenhouse gases, even without considering the carbon sequestration of the cork oak forest, the CO2 emissions associated with the production of natural cork stoppers are lower than those recorded by the production of plastic and aluminium closures, by about 10 times and 24 times, respectively.