The environmental cost of making a cotton T shirt is about £1.30 according to a study sponsored by the Danish Environment Ministry. The 16 kilos of clothing that the typical European buys each year have a full impact costed at about £50, or about £3 for every kilo. This means that environmental effect of all the UK’s clothes is probably a cost of about £2bn a year, representing about 5% of a person’s full eco-footprint. After energy use and food, clothing is the most important contributor to environmental stress. About 70% of this environmental cost comes from greenhouse gas emissions, with air and water pollution adding almost all the remainder of the footprint. Greenhouse gas emissions are heaviest for wool and silk. At an assumed cost of about £65 a tonne of CO2, virgin wool has an environmental cost of about £5 a kilo, even before the substantial extra costs from turning the fibres into a garment. Other environmental costs, such as water pollution, take this up to about £7 a kilo. Artificial fibres all have greenhouse gas emission costs of a small fraction of cotton, silk or wool.

Perhaps the most telling chart in the report is one which compares the environmental cost of generating fibres with their current market price. (This only includes the growing/manufacturing of the fibre, not the full impact of turning it into a piece of clothing). I have rounded the numbers and turned them into UK pounds

Fibre	Market price (£/kg)	Environmental cost per kg	Ratio environmental cost to market price

Cotton	£1.00	£3.00	About 3
Oil-based fibres	£1.50	£0.60	About 2/5
Synthetics (eg rayon)	£1.50	£0.60	About 2/5
Wool	£2.50	£8.00	About 3
Silk	£6	£18.00	About 3

Although cotton appears to be very cheap once the full environmental cost has been included – and in the case of this fibre this cost arises largely from water use – it is much more 'expensive' than artificial and synthetic fibres. Broadly speaking, the costs of all natural fibres should be quadrupled to reflect their true cost. Include the greater environmental impact of the later clothing manufacturing stages of wool and cotton and the differences are even starker.

If we reflected the full cost in the shop price of growing fibres and then turning them into clothing, would it change buying habits? Perhaps not in the case of wool. It might add 10% to the cost of an inexpensive woollen suit, or even less. However a quick look online suggests that I can buy T shirts for not much more than one pound. At the very least incorporating the full environmental cost would double this. Proper accounting for cotton might have substantial effect on purchase patterns, and also help to preserve scarce water resources in areas where cotton is grown.