What is the general consensus on the actual climate impact of “sustainable” fast‑fashion labels?

The term “sustainable” has become a marketing buzzword for countless fast‑fashion brands. Yet the climate community remains divided on whether these claims hold up under rigorous life‑cycle assessment (LCA). Do most experts believe that the modest material shifts—e.g., a portion of recycled polyester or Tencel blends—significantly reduce CO₂ emissions, or are they merely greenwashing maneuvers that obscure the core issue of overproduction?

Specifically, I am looking for a concise, community‑wide summary:

1. How credible are publicly available LCA data from brands such as H&M Conscious, Zara Join Life, and Patagonia’s recycled line?
2. Are the reductions (often quoted as 10‑30 % lower emissions) statistically meaningful when compared to a baseline of a fully circular, zero‑waste supply chain?
3. Do leading climate scientists view these incremental gains as a legitimate mitigation pathway, or do they consider them a distraction from systemic change?

I expect rigorous citations, not vague affirmations. If the consensus leans toward skepticism, please explain which methodological flaws are most commonly cited. If the consensus is more optimistic, detail the assumptions that make those optimistic scenarios plausible.

Bottom line: does the fashion industry’s “sustainability” narrative genuinely advance climate goals, or is it a convenient veneer for continued mass consumption?