古着市場の拡大が炭素排出に与える影響を解析(Second thoughts on secondhand? Why the resale market is expanding fashion’s carbon footprint)

2025-12-08 イェール大学

イェール大学の研究チームは、環境負荷の低減に寄与すると期待されてきたファッションのリセール(中古販売)市場が、実際にはアパレル全体の炭素排出を増やす可能性があることを明らかにした。研究によると、中古品の流通が拡大しても新品購入を確実に代替する割合は低く、多くの消費者は「中古も新品も両方買う」行動をとるため、総消費量がむしろ増える傾向があるという。さらに、オンライン販売・返品・配送のプロセスが追加的なCO₂排出を生む点も問題視された。調査モデルでは、新品の購入削減が中古購入の60%以上に達しなければ、リセール市場の拡大はネットの排出削減につながらないと算出。研究者らは、消費者の購買行動デザイン、返品削減、耐久性の高い製品設計、循環を前提とした政策の必要性を強調し、「リセールは自動的にサステナブルになるわけではない」と指摘している。

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古着ファッションの消費者は、持続可能性を訴えるにもかかわらず、ファストファッションの行動を示す Secondhand fashion consumers exhibit fast fashion behaviors despite sustainability narratives

Meital Peleg Mizrachi & Ori Sharon
Scientific Reports  Published:07 October 2025
DOI:https://doi.org/10.1038/s41598-025-19089-1

古着市場の拡大が炭素排出に与える影響を解析(Second thoughts on secondhand? Why the resale market is expanding fashion’s carbon footprint)

Abstract

The fashion industry contributes 2–8% of global greenhouse gas emissions, driven by rising clothing consumption and the proliferation of fast fashion. Fast fashion accelerates environmental harm through rapid production cycles, low costs, and short garment lifespans. Secondhand clothing markets are often promoted as a sustainable alternative, promising extended use and reduced waste. These markets have grown rapidly, with global sales reaching $177 billion in 2022 and projected to double by 2027. Despite this growth, few studies have empirically examined whether secondhand purchasing displaces or merely supplements primary market consumption. This study addresses that gap using a nationally representative survey of 1,009 U.S. consumers. We find that secondhand consumption is positively correlated with new clothing purchases (r = 0.58, p < 0.01), particularly among younger consumers and frequent shoppers. Cluster and principal component analyses reveal that highly engaged secondhand consumers also exhibit high overall consumption and short garment retention. Although many report high sustainability knowledge, such knowledge does not reliably predict sustainable behavior. Drawing on rebound and moral licensing theories, we suggest that secondhand purchases may psychologically or economically justify continued overconsumption. These findings challenge assumptions about resale’s environmental benefits and support policy interventions to realign resale practices with sustainability goals.

1901環境保全計画
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