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Climate Change

Is our plastic dependence accelerating climate change?

Figure 1. The cumulative effects of air pollution and plastic waste are endangering vulnerable marine species. Image credit: Microsoft Word commons

Reference: Royer, Sarah-Jeanne, Sara Ferrón, Samuel T. Wilson, David M. Karl. “Production of methane and ethylene from plastic in the environment.” PloS One 13, e0200574 (2018). Doi: https://doi.org/10.1371/journal.pone.0200574

Plastic? What’s the big deal?

Figure 2. Laysan Albatross with stomach full of plastic. Plastic cannot be broken down in the body so it fills the stomach and starves animals to death. Image credit: WikiMedia.

Since the 1950’s, over 6 billion tons of plastic have been produced globally. Less than 10% of plastic is recycled, and 8 million tons wind up in the ocean annually. Accumulation in the environment presents a substantial risk to vulnerable organisms. Plastic debris has been found in every environment from Mt. Everest to the depths of the Marianas Trench. Waste is conglomerated in ocean gyres and mixed to various depths by currents and waves. Exacerbating the problem, solar radiation degrades the waste into microplastics, which are difficult to clean up and easy to consume by marine life. Our increasing reliance on plastics has left many wondering about long-term impacts and how best to reduce waste.

 

The Study

Researchers from the University of Hawaii measured hydrocarbon gas emissions from degrading plastics. Emissions were measured from seven different types of plastic including the most abundant plastic and worst polluter, polyethylene (e.g. shopping bags). Experiments were conducted in rooftop temperature-controlled incubators exposed to solar radiation(energy, light, and heat from the sun). Different factors including plastic type, size, shape, and age were all considered, and control experiments were run in the dark. This study examined the effect of plastic shape and size by measuring emissions from pellets, powder, flakes, and linear low-density forms (e.g. plastic wrap). The effects of aging were also tested by incubating virgin pellets and previously aged plastic for 5+ months. Gas concentrations were quantified with gas chromatography and data were statistically analyzed using t-tests (α = 0.05).

What did they find? 

All plastic types were found to produce methane (CH4) and ethylene (C2H4) when exposed to sunlight, while all dark treatments produced very little – none. Shape and size experiments found that the smallest form (powder) emitted the highest concentration of gasses. In age experiments, plastics emitted gas for the entire study. The rate of gas production was also found to increase with time.

What does this mean?

Figure 3. Microplastics collected on a beach in The Azores. Image credit: WikiMedia

This work shows that methane, a significant greenhouse gas, is continuously being emitted from degrading plastic. In fact, these results suggest that as plastics degrade, the higher surface area to volume ratio actually causes an increasing rate of emission. Therefore, over time, plastics are getting smaller, becoming harder to clean-up, and emitting more greenhouse gases.

Methane is one of the most potent greenhouse gases. Non-CO2 gases made up nearly 30% of total emissions in 2010, and methane concentrations have increased by 150% since 1750 (IPCC Fifth Assessment Report). Greenhouse gases trap solar radiation in the Earth’s atmosphere resulting in a warming of the global mean temperature. For the first time, the use of single-use plastics has been directly linked to climate change. In a rapidly changing world, it is important for us to understand the ramifications of our actions. This study shows that the consequences of our plastic pollution are even greater than previously thought.

Although seemingly dire, this gives us more evidence than ever to take action. A good first step is banning single-use plastic bags; a step which 32 countries, 2 US states, and over 200 cities in North America have already taken.

What to do?

Shop Smart

  • Avoid plastics whenever and wherever possible
  • Bring reusable shopping bags
  • Decline a straw or bring a reusable one
  • Use bar soaps and shampoo rather than packaged

Advocate

  • Look for a ‘Ban the Bag’ group in your area or start one!
  • Petition for more/better garbage and recycling programs in your area
  • Join ocean education and conservation groups life Surfrider and Ocean Conservancy
  • Reduce! Reuse! Recycle!

 

Discussion

One Response to “Is our plastic dependence accelerating climate change?”

  1. I was thinking back to my childhood and we didn’t use plastics. Flour and sugar was measured out of a bin into paper bags. I was trying to remember about household garbage but frankly we didn’t have waste like this as nothing was plastic wrapped or in plastic containers.

    Posted by Ma | March 28, 2019, 1:56 pm

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