New Delhi, Aug. 9 -- "The next geopolitical contest may not begin over oil, semiconductors or rare earth minerals. It may begin with your old T-shirt."

A sweater dropped into a donation bin in Berlin may end up in Ghana's Kantamanto market, Panipat, India's recycling mills or, at worst, the vast dumps of Chile's Atacama Desert. In an age of global supply chains, clothes no longer carry only labels of fashion; they carry the politics of trade, climate responsibility and economic power. The afterlife of a garment has become as significant as its production.

This is what may be called Fast Fashion Diplomacy: the politics of deciding who bears responsibility for a garment after the consumer no longer wants it. It recognises that the environ...