" ... the sector was responsible for some 2.1 billion metric tons of greenhouse-gas (GHG) emissions in 2018 ..."
3 key areas:
Reducing emissions from upstream operations. ... transition from fossil fuels to renewable-energy sources ...
Reducing emissions from brands’ own operations ... greater use of recycled fiber ... use of sustainable transport ...
Encouraging sustainable consumer behavior ... use and reuse ... garment rental, resale, repair, and refurbishment ... washing and drying ... reduce landfill waste ...

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Read more https://www.mckinsey.com/industries/retail/our-insights/fashion-on-climate