This is how to ensure sustainable alternatives to plastic 

Plastic pollution has become one of the most pressing environmental challenges of our time, with marine plastics being the most recognizable problem linked to the use of plastic. The International Union for Conservation of Nature (IUCN) estimates that at least 14 million tons of plastic enter our ocean every year.

The very durable nature of plastic means that plastics could take thousands of years to break down in the environment, thereby causing harm to the health of our ocean and the life within it. Researchers have quantified this impact to represent a 1-5% decline in marine ecosystem service delivery, equating to an annual loss of $500–2,500 billion in the value of benefits derived from these services. Millions of people in coastal communities depend on these.

Ongoing environmental economics studies coupled with emerging toxicological science continue to shed light on the impact of plastic on both marine ecosystems and human health. But discussions around the impact of plastics on climate change have been scarce so far, especially in global climate talks. Plastics are made from fossil fuel, produce greenhouse gases throughout their lifecycle, and are projected to represent 20% of oil consumption and 15% of the global annual carbon budget by 2050. Single-use plastics, in particular, represent a high carbon footprint and loss of energy resources that are simply discarded after only a short, one-time use.

New materials made from other sources than oil have started to step into replacing various segments of the plastics market, especially single-use plastics. Those from natural, biological sources are known as bioplastics or biopolymers. As the bioplastics and biopolymers market grows exponentially to meet the increasing demand for plastic substitutes, biodegradability and human health impact are critical factors to evaluate it – but so is the carbon footprint which is often overlooked when it comes to plastic substitutes.

Paper and polylactic acid (PLA) are currently the two most popular alternatives to single-use plastics. While PLA is only biodegradable in industrial composting plants, both paper and bioderived plastics like PLA and many other “plant-based” compostable alternatives could be major greenhouse gas emitters.

Taking paper as an example, study after study shows that paper bags have a much higher carbon footprint than conventional plastic shopping bags. In fact, a meta-analysis of seven life cycle assessments (LCAs) conducted by UNEP in 2020 concluded that paper bags do contribute less to the impacts of littering; however, in most cases, they are significantly worse when it comes to climate impacts, eutrophication, and acidification, compared to single-use plastic bags.

Another study that compared the use of grocery bags made from compostable plastics to traditional grocery bags made from low-density polyethylene (LDPE) found similar results. The production of compostable plastic bags and paper bags required almost 3 times the energy input needed for the production of the same number of traditional plastic bags. Similarly, these bags generated greenhouse gas emissions up to three times higher than the traditional plastic bag.

Similar trends were noticed in a limited comparative LCA study comparing single-use plastic drinking straws to its most common alternatives, the PLA straw, and the paper straw. In terms of energy demand, the single-use plastic straw had nearly half the energy demand of PLA straws and paper straws. Similarly, the PLA straw and the paper straw had a Global Warming Potential nearly three times more than the single-use plastic straw. The study also found that the use of a (reusable) metal straw would only have a significantly lower impact than plastic straws provided that the metal straws are washed using cold tap water and the standard washing time is cut to half after each use.

Given that the largest share of the carbon footprint was coming from the primary material used in single-use straws, the use of naturally occurring carbon dioxide capturing materials such as seaweed could be a game-changer in the alternatives to plastics markets. To this end, a preliminary assessment estimated the net carbon dioxide sequestration potential of a seaweed-based straw prototype by LOLIWARE Inc. to be less than all other conventional straws.

What the seaweed-based straw removes from the atmosphere in terms of carbon dioxide is 95 percent of what a standard plastic straw emits throughout its life cycle in this study. This means that if the product’s life cycle is factored in the straw’s design, manufacture, and end-of-life scenarios when scaled up, the seaweed-based straw holds the potential to be carbon neutral or even carbon negative. This alongside seaweed’s contribution to the socioeconomic wellbeing of millions of people in coastal communities worldwide, especially women makes seaweed a well-rounded candidate to replace plastic.

At a time when the world is scrambling to meet the Paris Agreement goals and divest from fossil fuels, plastic production is being ramped up to double by 2040. The fossil fuel industry, in particular, has been attempting to diversify its revenues by investing in plastics and using those revenues to subsidize the large fixed-cost infrastructure built around oil refineries.

Now that world leaders set out to pen the finer details and terms of a Paris Agreement-style global treaty on plastic pollution agreed upon at the United Nations Environment Assembly in Nairobi last week, the impact of plastics on climate change will have to be on top of the agenda. The treaty would have to require governments to align on setting ambitious goals to tackle plastic pollution from a life-cycle perspective, including cuts on plastic production, and be rooted in the principles of human rights and environmental justice.

Plastic bans are not new; we have seen country-, city- and establishment-level bans on single-use plastic such as drinking straws with the intention of reducing or eliminating their use. However, these bans automatically led to the replacement of plastic straw with paper or fiber-based or bioplastic (PLA) alternatives with the assumption that these alternatives would reduce the negative environmental impacts linked to plastic straw use – when they don't.

This is where the global plastic pollution treaty would have to be particularly cautious. The final terms of the global plastic pollution treaty should be bold enough to consider single-use plastic bans, but only within the context of a science-based, complementary plastic policy package that seeks to eradicate unnecessary plastic consumption, considers the overall environmental impact of various plastic alternatives – beyond biodegradability –, and provides incentives for alternative use. For instance, a default choice modification such as "a straw upon request"-framework combined with certification and environmental labeling, financial investments in both waste management infrastructure and research as well as development of new biomaterials such as seaweed biopolymers is recommended as the most effective set of policies to reduce single-use plastic straw consumption.

After all, a net-zero emissions future will necessitate plastic alternatives that are truly biodegradable, scalable, affordable, and most importantly, significantly lower in their energy use and carbon footprint, even being carbon neutral and carbon negative where possible.