TED Climate: What happens to the plastic you throw away? (Transcript)
Wednesday, August 11, 2021
Hi and welcome to TED Climate, a podcast from the TED Audio Collective. I’m your host, Dan Kwartler. On this show, we’re staring straight into the abyss of the climate crisis. Don’t worry though, we promise not to bum you out too much. Each episode of this season we’ll look at two different sides of the same issue. We’ll explore big questions like, “Could we transition to only renewable energy?” and “What would happen if every human disappeared?”. But we’ll also dig into the smaller things that affect your day to day life. Hopefully, these stories will reveal some small changes you can make to feel like you’re doing something, instead of just, ya know, tumbling toward inevitable doom.
This week’s topic? Plastic.
Our first question’s probably one you asked on your last shopping trip: “Which bag should I use? Plastic, paper, or cloth?” Cities around the world have begun moving away from single-use plastic bags -- you know, the thin and flimsy kind you might see stuck in a tree? But what exactly is the environmental impact of using a plastic bag as opposed to another kind of bag
Surely a paper bag or a cotton tote would be the better option. But is that really true?
Each of these three materials has a unique environmental impact that’s determined by three things: its carbon footprint, its potential to be reused and recycled, and its degradability. So, to get the full story on these grocery bags let's talk about how they’re made, how they’re used, and where they ultimately go.
Let’s start with plastic. The typical thin and flimsy plastic bag is made of high-density polyethylene, commonly known as HDPE. Producing this material requires extracting petroleum from the ground and applying extreme heat. This creates a polymer resin is then transported alongside additional ingredients like titanium oxide and chalk to a bag manufacturing plant. Here, coal powered machines melt the materials down and spin them into sheets of plastic, which are then folded into bags. By the time a plastic bag reaches its final destination, it’s contributed an estimated 1.6 kg of carbon dioxide into the atmosphere.
That’s the same amount of carbon a car produces, driving a little over 6 kilometers. But the alternatives actually possess a much larger carbon footprint. Paper is made from wood pulp, and when you account for the carbon cost of removing trees from their ecosystems, a single paper bag can be responsible for about 5.5 kg of carbon dioxide. Meanwhile, growing cotton is an extremely energy and water intensive process. The production of a single cotton tote emits an estimated 272 kg of carbon dioxide.
When we compare carbon footprints, plastic bags are the clear winner. But environmental impact is also determined by how the bag is used. Reusing or recycling these bags significantly offsets their environmental toll by reducing demand for new production. To quantify that offset, we can divide the bag’s carbon footprint by the number of times it’s reused. For example, if a typical paper bag is reused three times, it has a lower net impact than a single-use plastic bag. The carbon footprint of a cotton tote can similarly be lowered, if it’s reused 131 times.
Of these three options, durable cloth totes are most likely to be reused. Evidence shows paper bags are quickly discarded due to their tendency to tear. This issue plagues HDPE bags as well. But even when they’re made to avoid tearing, their widespread availability makes it easy to treat them as single-use items. Fortunately, researchers estimate that 40% of HDPE bags are reused at least once for throwing out waste.
Recycling these bags also offsets their carbon footprint, but it’s not universally possible for each material. Many countries lack the infrastructure to efficiently recycle plastic bags. Cotton totes are perhaps even more difficult to break down and process, but since they’re often reused for long periods, they’re still least likely to end up in landfills.
Whenever these bags aren’t recycled, we have to think about that third factor: degradability. Since HDPE bags are heat-resistant and insoluble, they stick around long after we’re done with them. Partially broken down plastic can circulate in ecosystems for centuries. Cotton on the other hand degrades substantially in a few months, and paper bags break down completely in just 90 days.
So, which of these three bags should you use? The answer is...kind of, none of them. It turns out there’s another, even more environmentally friendly bag, one that combines many of the best features of the bags we’ve discussed. I’m talking about those reusable bags they sell at the grocery store for a dollar or two. These sturdier plastic bags are made of polyester, vinyl and other tough plastics. They’re durable and reusable, like cotton, but have a lower carbon footprint than cotton or paper. And they’re already used worldwide. A small collection of these bags should last a lifetime— making them the best option for the planet, and your groceries.
Alright, so maybe that was kind of a trick question. But it looks like no matter what bag you use, what's most important is to use it again. And again. And again, pretty much forever. Reusing your bags dramatically decreases their environmental impact. Especially because when you don't reuse something, its journey after you trash it can be way longer than you think.
Remember earlier, when I said that plastic can circulate in our ecosystems for centuries? That gets to our next question: what actually happens to the plastic we throw away?
Here’s the story of three plastic bottles. Their journeys are about to diverge with outcomes that impact nothing less than the fate of the planet. But they weren't always this way. To understand where these bottles end up, let’s first explore their origins.
The heroes of our story were conceived in an oil refinery. The plastic in their bodies was formed by chemically bonding oil and gas molecules together to make monomers. These monomers were then bonded into long polymer chains to make plastic in the form of millions of pellets. Those were melted at manufacturing plants and reformed in molds to create the resilient material that makes up these bottles. Machines filled them with water and they were then wrapped, shipped, bought, opened, consumed and unceremoniously discarded. [And now here they lie, poised at the edge of the unknown.]
Bottle number one, like hundreds of millions of tons of its plastic brethren, ends up in a landfill. This huge dump expands each day as more trash comes in and continues to take up space. As plastics sit there being compressed amongst layers of junk, rainwater flows through the waste and absorbs the water-soluble compounds it contains. Some of these are highly toxic. Together, they create a harmful stew called leachate, which can move into groundwater, soil and streams, poisoning ecosystems and harming wildlife. It could take our first bottle an agonizing 1,000 years to decompose.
Bottle number two's journey is stranger but, unfortunately, just as depressing. It floats on a trickle that reaches a stream, a stream that flows into a river, and a river that reaches the ocean. After months lost at sea, it's slowly drawn into a massive vortex, where trash accumulates, a place known as the Great Pacific Garbage Patch. Here the ocean's currents have trapped millions of pieces of plastic debris. This is one of five plastic-filled gyres in the world's seas. Places where the pollutants turn the water into a cloudy plastic soup. Some animals, like seabirds, get entangled in the mess. They, and others, mistake the brightly colored plastic bits for food. Plastic makes them feel full when they're not, so they starve to death and pass the toxins from the plastic up the food chain. For example, these birds might be eaten by lanternfish, which are eaten by squid, which are eaten by tuna, which are then eaten by us. And most plastics don't biodegrade, which means they're destined to break down into smaller and smaller pieces called micro plastics, which might rotate in the sea eternally.
But bottle number three is spared the cruel purgatories of its siblings because it’s getting recycled. A truck brings it to a plant where it’s squeezed flat and compressed into a block with a bunch of other bottles. Okay, this sounds pretty bad, too, but hang in there. It gets better. The blocks are shredded into tiny pieces, which are washed and melted, so they become the raw materials that can be used again. As if by magic, bottle number three is now ready to be reborn as something completely new.
So there you have it. My big takeaways for this episode? Good grief. First off, buy less plastic, like buy no plastic. It’s not easy because plastic is everywhere, but it’s a small change you can make that can have a huge consequence. Second, when you do buy plastic, try to reuse it as much as possible. You know, reuse that plastic take-out container instead of buying new ones to store your food. And third, for anything you can’t reuse, find out if it can be recycled in your area -- if it’s not collected with normal recycling, you might still be able to drop it off at your local grocery store.
Well, that’s it for this week. Thanks for listening and join me next time for more knowledge to help you fight off the crushing reality of the climate crisis. But seriously, learning how all this stuff works is actually the only way we can change things. And we CAN change things. And it takes everyone, so thank you for listening.
You can get more involved by joining Countdown, TED’s global initiative to accelerate solutions to the climate crisis in collaboration with Future Stewards. Find out more at countdown.ted.com.
TED Climate is produced and edited by Sheena Ozaki and hosted by me, Dan Kwartler. These lessons were originally made in animated form by the TED-Ed team, so special thanks to them, and to Michelle Quint, Anna Phelan, and Colin Helms.