Dumped plastic left in sun gives off greenhouse gases
PLASTICS dumped outside react with sunlight and give off greenhouse gases that can cause global warming, a study has found.
The biggest producer of greenhouse gases was polyethylene, a material commonly used to make carrier bags.
The research found that all of the most common plastics give off two greenhouse gases – methane and ethylene – when they come into contact with sunlight.
Writing in the journal PLOS One, scientists said polyethylene is the plastic most commonly dumped outside – and also the material which is ‘most prolific’ at producing methane and ethylene.
Methane is considered 20 to 30 times more harmful than carbon dioxide when it comes to trapping warmth in the earth’s atmosphere in a ‘greenhouse effect’.
Other plastics found to produce the gases included polystyrene, high and lowdensity polyethylene – which are used to make plastic bottles – and polyethylene terephthalate (PET).
The gases are produced as larger pieces of plastic break down into smaller pieces known as microplastics.
This is because plastics are made of either oil or gas, which are fossil fuels. Around 8 per cent of all oil and gas production now goes into making plastic.
The researchers found that as plastic becomes weathered in the environment, pits and cracks increase surface area and so give off more greenhouse gases.
However, emissions from dumped plastic do not feature in official estimates of greenhouse gas emissions.
Professor David Karl, of the Centre for Microbial Oceanography at the University of Hawaii, said emissions from decaying plastic may be ‘ significant’ but are ‘not budgeted for’.
He added: ‘Plastic represents a source of climate-relevant trace gases that is expected to increase as more plastic is produced and accumulated in the environment.’
Study co-author Sarah- Jeanne Royer said: ‘ 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.’ A recent study estimated that humans have created 6.3 billion tons of plastic waste, of which 79 per cent is still either in landfill or the environment. If production continues at current rates, this will reach 12 billion tons by 2050.
The Daily Mail led calls for a 5p levy on plastic bags and is campaigning for the introduction of a deposit return scheme to reduce the vast numbers of plastic bottles dumped in our rivers and seas.