Science

Degrading plastics emit greenhouse gases

Degrading plastics emit greenhouse gases

This is Dr. Sarah-Jeanne Royer holding microplastics at Kamilo Point on Big Island on February 14, 2018.

A study published yesterday (August 1) in PLOS ONE reports that plastics-ranging from construction materials to plastic bags-release the greenhouse gases methane and ethylene after being exposed to sunlight and beginning to degrade.

Taiwan started recycling plastic more than a decade ago and today it boasts more than 70 percent recycling rates, according to the Environmental Protection Administration.

The researchers also discovered that during a 212-day experiment, virgin pellets of LDPE emitted increased greenhouse gases, and when LDPE debris found in the ocean were exposed to sunlight, they also released a considerable amount of greenhouse gases.

Greenpeace senior oceans campaigner Louise Edge, said:"Ocean plastic pollution has already been described as a "toxic time-bomb" by the United Nations, and this new study suggests that when plastic degrades in sunlight, it emits greenhouse gases which are harmful to our climate".




They tested a wide range of plastics including polycarbonate, acrylic, polypropylene, polyethylene terephthalate, polystyrene and both high and low density polyethylene (LDPE). Polyethylene used in plastic shopping bags was the biggest contributor to greenhouse gases and is also the most produced and discarded plastic in the world. When these plastics are further broken down or cracked, the study authors say the rate of gas production can further accelerate. Microplastics - smaller pieces of plastic particles found to move up the food chain and in almost every corner of the world, including Antarctica - may further accelerate GHG production.

"Our results show that plastics represent a heretofore unrecognized source of climate-relevant trace gases that are expected to increase as more plastic is produced and accumulated in the environment", the study authors write in their paper.

"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, especially single use plastic", said Royer.

Greenhouse gases have a direct impact on climate change and have been previously linked to changing sea levels, increasing global temperatures, drought and erosion.

'This source is not yet budgeted for when assessing global methane and ethylene cycles - and may be significant'.