This article summarises a study looking at the role of materials substitution in reducing lifecycle emissions from plastic packaging. The key conclusions were as follow:

Modern packaging solutions are essential to efficient logistics and retailing. At the same time, there is increasing concern with the environmental impact of packaging, from littering and leakage to world oceans, to their climate impact. 
Plastic packaging in particular has recently been in the limelight. Plastics have many properties that are essential to packaging. However, they are also fossil materials that are challenging to fit into a future low-carbon economy. Indeed, even as other emissions falls, EU CO2 emissions from plastics packaging are set to double to 2050 on current course, from 43 to 85 Mt CO2 per year. While 43 Mt are just 1% of EU 2016 emissions, 85 Mt in 2050 would claim 30% of the remaining emissions, given a 95% reduction target from 1990’s levels. 
To address this, multiple approaches are needed. Increased recycling is a necessity, but even in a stretch scenario would only solve 30-40% of the problem. Likewise, low-emitting production of plastics will be needed, but can be very resource intensive. By one estimate, making just EU packaging plastics CO2 free would require 560 TWh, or 80% of all electricity produced from renewable energy sources in the EU today. 
This study investigates switching from fossil to renewable materials as a complementary strategy, one that is surprisingly absent in current discussions. Specifically, the study finds that replacing plastics with wood fibre has significant promise, for two main reasons. First, as a renewable material, fibre is much easier to render CO2-neutral. Indeed, just current EU and industry targets would cut 65% of emissions from fibre production, whereas those from plastics fall by just 20%. Second, there is significant substitution potential. We find that 25% of current plastics use in packaging could be replaced, without significant compromise on functionality. Seen in this light, substitution would not be about replacing all plastics, but reserving their use to areas where their properties are indispensable, while turning to renewable materials where possible. 
Companies such as brand owners and retailers can start already now to consider materials substitution alongside recycling and other options to bring about sustainable packaging for their products. Policymakers in turn can recognise the role of renewable materials among the menu of solutions required for climate targets.