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Environment

Decomposing Plastic Revealed as Hidden Source of Greenhouse Gas Emissions

Why Global Citizens Should Care
Plastic pollution is a long-term environmental and public health threat that the United Nations’ is campaigning to reduce. You can take action on this issue here.


It’s long been known that plastic waste releases toxic chemicals into the environment, can injure and kill marine life, and breaks down into microplastics that contaminate water and food supplies.

It also generates greenhouse gas emissions as it degrades, according to a new study published in the science magazine Plos One.

A team of researchers at the University of Hawaii studied the decomposition of various kinds of plastic and determined that methane and ethylene, two greenhouse gas emissions, are released in the process.

Methane warms the planet at up to 86 times the rate of carbon, while ethylene is another leading emission.

Take Action: Say No to Using Single-Use Plastics

Plastic is made from fossil fuels, so the finding is not exactly startling, but it’s the first time that specific measurements have been taken of the phenomenon.

Plus, this source of greenhouse gas emissions has largely been left out of climate change forecasting models, according to the report, and its future incorporation could alter the projected rate at which the planet warms.

Another reason to pay attention to this data, the researchers contend, is that plastic production is expected to dramatically increase over the next decade, and the amount of plastic waste decomposing in the environment will similarly increase.

It’s not like a decomposing plastic cup releases as much emissions as a commuting car, but when it happens billions of times, it adds up, the researchers note.

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“Considering the amounts of plastic washing ashore on our coastlines and the amount of plastic exposed to ambient conditions, our finding provides further evidence that we need to stop plastic production at the source,” lead author Dr. Sarah-Jeanne Royer told the Daily Mail. “Especially single-use plastic.”

Some of the types of plastic that researchers studied include polycarbonate, acrylic, polypropylene, polyethylene terephthalate (PET), polystyrene, high-density polyethylene (HDPE), and low-density polyethylene (LDPE).

These plastics are found in common items like food packaging, fabrics, and toys.   

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Polyethylene was found to emit the most methane and ethylene, and it’s a plastic used to make single-use shopping bags. Globally, countries and cities have been enacting bans on plastic bags because of how frequently they pollute marine ecosystems.

Other restrictions on single-use plastics are being devised, and this new data could give regulators more evidence when crafting policy.