With a score of 30.7, silk is ranked second on the index. Although silk manufacturing produces significant amounts of greenhouse gases, it receives great marks for sustainability.
With a score of 26.8, Cotton places third. Despite its image as being environmentally friendly, cotton is penalised for using a lot of water and land, bleaches, and other chemicals during processing, which places it in a middle of the pack. Wool and bamboo receive even lower marks because their rough fibres need much more resources and labor-intensive processing.