The PLA polymer environmental footprint associated with CO2 emissions during PLA production is very small compared to the footprints of all the other synthetic fibres.
Notes - Ingeo: Vink E.T.H. and all. The eco-profiles for current and near-future NalureWorks® poIyIactide (PLA) production. Industrial Biotechnology, Volume3, Number1, 2007, Page58-al. - Fossil based polymers: PlasticsEurops; www.lca.plasticseurope.org - GWP100 Factors [Global Warming Potential] according to IPCC (CO2=1, CH4=23, N20=296).
Still another advantage is that PLA polymer production consumes less energy.